Campbell Scientific CR7 User Manual

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CR7 MEASUREMENT AND CONTROL SYSTEM

INSTRUCTION MANUAL

REVISION: 7/97

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WARRANTY AND ASSISTANCE

The CR7 MEASUREMENT AND CONTROL SYSTEM is warranted by CAMPBELL SCIENTIFIC, INC. to be free from defects in materials and workmanship under normal use and service for thirty-six (36) months from date of shipment unless specified otherwise. Batteries have no warranty. CAMPBELL SCIENTIFIC, INC.'s obligation under this warranty is limited to repairing or replacing (at CAMPBELL SCIENTIFIC, INC.'s option) defective products. The customer shall assume all costs of removing, reinstalling, and shipping defective products to CAMPBELL SCIENTIFIC, INC. CAMPBELL SCIENTIFIC, INC. will return such products by surface carrier prepaid. This warranty shall not apply to any CAMPBELL SCIENTIFIC, INC. products which have been subjected to modification, misuse, neglect, accidents of nature, or shipping damage. This warranty is in lieu of all other warranties, expressed or implied, including warranties of merchantability or fitness for a particular purpose. CAMPBELL SCIENTIFIC, INC. is not liable for special, indirect, incidental, or consequential damages.

Products may not be returned without prior authorization. To obtain a Returned Materials Authorization (RMA), contact CAMPBELL SCIENTIFIC, INC., phone (435) 753-2342. After an applications engineer determines the nature of the problem, an RMA number will be issued. Please write this number clearly on the outside of the shipping container. CAMPBELL SCIENTIFIC's shipping address is:

CAMPBELL SCIENTIFIC, INC.

RMA#_____ 815 West 1800 North Logan, Utah 84321-1784

CAMPBELL SCIENTIFIC, INC. does not accept collect calls. Non-warranty products returned for repair should be accompanied by a purchase order to cover the repair.

815 W. 1800 N. Logan, UT 84321-1784 USA Phone (435) 753-2342 FAX (435) 750-9540 www.campbellsci.com

Campbell Scientific Canada Corp. 11564 -149th Street Edmonton, Alberta T5M 1W7 CANADA Phone (780) 454-2505 FAX (780) 454-2655

Campbell Scientific Ltd. Campbell Park 80 Hathern Road Shepshed, Loughborough LE12 9GX, U.K. Phone +44 (0) 1509 601141 FAX +44 (0) 1509 601091

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CR7 OPERATOR'S MANUAL

TABLE OF CONTENTS

PAGE

WARRANTY AND ASSISTANCE

SELECTED OPERATING DETAILS..............................................................................................v

CAUTIONARY NOTES......................................................................................................................vi

OVERVIEW

OV1. PHYSICAL DESCRIPTION

OV1.1 700X Control Module ..........................................................................................................OV-1

OV1.2 720 I/O Module.................................................................................................................... OV-2

OV1.3 Enclosures and Connector Options .................................................................................... OV-2

OV2. MEMORY AND PROGRAMMING CONCEPTS

OV2.1 Internal Memory.................................................................................................................. OV-3

OV2.2 CR7 Instruction Types......................................................................................................... OV-6

OV2.3 Program Tables and the Execution and Output Intervals ................................................... OV-6

OV3. PROGRAMMING THE CR7

OV3.1 Functional Modes................................................................................................................ O V-8

OV3.2 Key Definition......................................................................................................................OV-8

OV3.3 Programming Sequence .....................................................................................................OV-8

OV3.4 Instruction Format............................................................................................................... OV-9

OV3.5 Entering a Program.............................................................................................................OV-9

OV4. PROGRAMMING EXAMPLE

OV4.1 Measurement.................................................................................................................... OV-10

OV4.2 Output ...............................................................................................................................OV-12

OV4.3 Editing an Existing Program.............................................................................................. OV-14

OV4.4 EDLOG Program Listing ...................................................................................................OV-14

OV5. DATA RETRIEVAL OPTIONS................................................................................ OV-15

OV6. SPECIFICATIONS...................................................................................................... OV-17

TABLE OF CONTENTS

PROGRAMMING

1. FUNCTIONAL MODES

1.1 Program Tables - *1, *2, and *3 Modes ................................................................................. 1-1

1.2 Setting and Displaying the Clock - *5 Mode........................................................................... 1-2

1.3 Displaying and Altering Input Memory or Flags - *6 Mode..................................................... 1-2

1.4 Compiling and Logging Data - *0 Mode ................................................................................. 1-3

1.5 Memory Allocation - *A........................................................................................................... 1-4

1.6 Memory Testing and System Status - *B Mode ..................................................................... 1-5

1.7 *C Mode - Security................................................................................................................. 1-6

1.8 *D Mode - Save or Load Program.......................................................................................... 1-7

2. INTERNAL DATA STORAGE

2.1 Final Storage Areas, Output Arrays, and Memory Pointers................................................... 2-1

2.2 Data Output Format and Range Limits .................................................................................. 2-2

2.3 Displaying Stored Data on Keyboard/Display - *7 Mode........................................................ 2-3

3. INSTRUCTION SET BASICS

3.1 Parameter Data Types........................................................................................................... 3-1

3.2 Repetitions/Card Number....................................................................................................... 3-1

3.3 Entering Negative Numbers................................................................................................... 3-1

3.4 Indexing Input Locations ........................................................................................................ 3-2

3.5 Voltage Range and Overrange Detection .............................................................................. 3-2

3.6 Output Processing.................................................................................................................. 3-2

3.7 Use of Flags: Output and Program Control........................................................................... 3-3

3.8 Program Control Logical Constructions ................................................................................. 3-4

3.9 Instruction Memory and Execution Time................................................................................ 3-6

3.10 Error Codes............................................................................................................................ 3-9

DATA RETRIEVAL/COMMUNICATION

4. EXTERNAL STORAGE PERIPHERALS

4.1 On-Line Data Transfer - Instruction 96, *4 Mode ................................................................... 4-1

4.2 Manually Initiated Data Output - *9 Modes............................................................................. 4-2

4.3 Storage Module...................................................................................................................... 4-3

4.4 Printer Output Formats........................................................................................................... 4-4

5. TELECOMMUNICATIONS

5.1 Telecommunications Commands .......................................................................................... 5-1

5.2 Remote Programming of the CR7.......................................................................................... 5-3

6. 9 PIN SERIAL INPUT/OUTPUT

6.1 Pin Description....................................................................................................................... 6-1

6.2 Enabling Peripherals.............................................................................................................. 6-2

6.3 Interrupting Data Transfer to Storage Peripherals................................................................. 6-2

6.4 Telecommunications - Modem Peripherals............................................................................ 6-2

6.5 Interfacing with Computers, Terminals, and Printers............................................................. 6-2

TABLE OF CONTENTS

PROGRAMMING EXAMPLES

7. MEASUREMENT PROGRAMMING EXAMPLES

7.1 Single Ended Voltage-LI200S Silicon Pyranometer................................................................7-1

7.2 Differential Voltage Measurement...........................................................................................7-1

7.3 Thermocouple Temperatures Using 723-T Reference...........................................................7-2

7.4 Thermocouple Temperatures Using an External Reference Junction....................................7-2

7.5 Thermocouples for Differential Temperature Measurement...................................................7-3

7.6 Temperature with Calibrated Thermocouples.........................................................................7-4

7.7 107 Temperature Probe..........................................................................................................7-5

7.8 207 Temperature and RH Probe.............................................................................................7-5

7.9 Anemometer with Photochopper Output.................................................................................7-6

7.10 Tipping Bucket Raingage with Long Leads.............................................................................7-6

7.11 100 ohm PRT in 4 Wire Half-Bridge........................................................................................7-7

7.12 100 ohm PRT in 3 Wire Half-Bridge........................................................................................7-8

7.13 100 ohm PRT in 4 Wire Full-Bridge ........................................................................................7-9

7.14 Pressure Transducer-4 Wire Full-Bridge ..............................................................................7-10

7.15 Lysimeter-6 Wire Load Cell...................................................................................................7-11

7.16 227 Gypsum Soil Moisture Block ..........................................................................................7-13

7.17 Nonlinear Thermistor in Half Bridge (CSI Model 101)...........................................................7-14

8. PROCESSING AND PROGRAM CONTROL EXAMPLES

8.1 Computation of Running Average...........................................................................................8-1

8.2 Rainfall Intensity......................................................................................................................8-2

8.3 SUB 1 Minute Output Interval Synched to Real Time.............................................................8-3

8.4 Analog Output to Strip Chart...................................................................................................8-4

8.5 Converting 0-360 Wind Direction Output to 0-540 for Strip Chart...........................................8-5

8.6 Covariance Correlation Programming Example......................................................................8-6

INSTRUCTIONS

9. INPUT/OUTPUT INSTRUCTIONS.....................................................................................9-1

10. PROCESSING INSTRUCTIONS......................................................................................10-1

11. OUTPUT PROCESSING INSTRUCTIONS...................................................................11-1

12. PROGRAM CONTROL INSTRUCTIONS......................................................................12-1

MEASUREMENTS

13. CR7 MEASUREMENTS

13.1 Fast and Slow Measurement Sequence ...............................................................................13-1

13.2 Single-Ended and Differential Voltage Measurements .........................................................13-1

13.3 The Effect of Sensor Lead Length on the Signal Settling Time ............................................13-3

13.4 Thermocouple Measurements............................................................................................13-11

13.5 Bridge Resistance Measurements ......................................................................................13-15

13.6 Resistance Measurements Requiring AC Excitation ..........................................................13-19

13.7 Pulse Count Measurements................................................................................................13-20

iii

TABLE OF CONTENTS

INSTALLATION

14. INSTALLATION

14.1 Environmental Enclosure, Connectors and Junction Boxes ................................................ 14-1

14.2 System Power Requirements and Options .......................................................................... 14-2

14.3 Humidity Effects and Control................................................................................................ 14-5

14.4 Recommended Grounding Practices................................................................................... 14-5

14.5 Use of Digital Control Ports for Switching Relays ................................................................ 14-6

15. I/O CARD ADDRESSING AND MULTIPLE I/0 MODULES

15.1 I/O Card Identification Number Decoding ............................................................................ 15-1

15.2 Use of Multiple I/O Modules................................................................................................. 15-4

APPENDICES

A. GLOSSARY..............................................................................................................................A-1

B. CR7 PROM SIGNATURES FOR SYSTEMS EQUIPPED WITH

STANDARD SOFTWARE....................................................................................................B-1

C. BINARY TELECOMMUNICATIONS

C.1 Telecommunications Command With Binary Responses......................................................C-1

C.2 Final Storage Format .............................................................................................................C-3

C.3 Generation of Signature.........................................................................................................C-4

D. CALIBRATION PROCEDURES

D.1 Voltage Reference Calibration Procedure..............................................................................D-1

D.2 Clock Calibration Procedure ..................................................................................................D-2

LIST OF TABLES.......................................................................................................................... LT-1

LIST OF FIGURES........................................................................................................................LF-1

INDEX ................................................................................................................................................... I-1

SELECTED OPERATING DETAILS

The channel numbering on the Analog Input Card refers to differential measurements. Single ended measurements assume the HI and LO side of each differential channel are two independent single ended channels, e.g., the HI and LO side of differential channel 2 are single ended channels 3 and 4 respectively.

When multiple measurements are specified in one measurement instruction (through use of the "Repetitions Parameter") the CR7 I/O Module is capable of sequencing through 500 fast, single-ended measurements per second. This specification is the MEASUREMENT SPEED and should not be confused with throughput which is the rate at which measurements are made, converted to engineering units and stored in Final memory. With the 700X Control Module (6303 CPU board), the maximum throughput rate for fast, single-ended measurements is approximately 310 measurements per second (1 second execution: Instruction 1 entered 4 times, 3 times with 99 repetitions, once with 11 repetitions).

Data is stored in Final Memory only by Output Processing Instructions and only when the Output Flag is set.

The default case for data stored in Final Memory is low resolution (4 characters). High resolution values (5 characters) must be specified through use of Instruction 78. All data contained in Input Memory is displayed (*6) as HIGH RESOLUTION (5 characters) but the default case for all data stored in Final Memory is LOW RESOLUTION unless high resolution is specified through use of Instruction 78.

Floating Point Format - The computations performed in the CR7 use floating point arithmetic. CSI's 4 byte floating point numbers contain a 23 bit binary mantissa and a 6 bit binary exponent. The largest and smallest numbers that can be stored and processed are 9 x 1018 and 1 x 10

The computations performed in the CR7 are done in floating point arithmetic. Internally, the number is stored and processed as a binary number with a 23 bit binary mantissa and a 6 bit binary exponent. The largest and smallest numbers that can be stored and processed are 9 x 1018 and 1 x 10 of the mantissa limits the resolution of the arithmetic to 1 part in 223 binary (1.3 x 10 decimal).

Time is stored with data in Final Memory only if specifically requested through use of the Real Time Instruction 77.

Data in Final Storage can be erased without altering the program by using the *A Mode to repartition memory. The simplest method is to re-enter the current allocation for Input Storage (32 locations is the default allocation). All memory can be erased and the CR7 completely reset by entering 1744 for the number of bytes left in Program Memory.

On-line (as opposed to a manually initiated dump) data transfer to peripherals (printer, storage module, etc.) occurs only if enabled through use of the *4 Mode or Instruction 96.

Data transfer to cassette tape is no longer supported.

-19

, respectively.

-19

respectively. The size

CAUTIONARY NOTES

The typical current drain for the CR7 is approximately 100 mA while executing and 8-10 mA quiescent. Do not allow the lead-acid batteries (2.5 Ahr) to drop below 11.76 V as irreversible battery damage may result.

An external battery connected to the I/O Module +12V and ground terminals continues to power the CR7 system even though the CR7 power switch is off. Reverse polarity protection is NOT provided on this connection so exercise extreme care if connecting external power supplies.

Damage will occur to the analog input channel circuitry if voltages in excess of +16V are applied for a sustained period.

A POTENTIALLY DANGEROUS situation can result due to hydrogen gas build up if the CR7 is housed in a gas tight enclosure and the internal lead acid batteries are shorted or overcharged. Hydrogen concentration levels may occur which are capable of causing injury or equipment damage if ignited.

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

The CR7 Measurement and Control System combines precision measurement with processing and control capability in a battery operated system.

Campbell Scientific, Inc. provides three documents to aid in understanding and operating the CR7:

1. This Overview

2. The CR7 Operator's Manual

3. The CR7 Prompt Sheet This Overview introduces the concepts required to take advantage of the CR7's capabilities. Hands-on

programming examples start in Section OV4. Working with a CR7 will help the learning process, so don't just read the examples, turn on the CR7 and do them. If you want to start this minute, go ahead and try the examples, then come back and read the rest of the Overview.

The sections of the Operator's Manual which should be read to complete a basic understanding of the CR7 operation are the Programming Sections 1-3, the portions of the data retrieval Sections 4 and 5 appropriate to the method(s) you are using (see OV5), and Section 14 which covers installation and maintenance.

Section 6 covers the details of serial communications. Sections 7 and 8 contain programming examples. Sections 9-12 have detailed descriptions of the programming instructions, and Section 13 goes into detail on the CR7 measurement procedures.

The Prompt Sheet is an abbreviated description of the programming instructions. Once familiar with the CR7, it is possible to program it using only the Prompt Sheet as a reference, consulting the manual if further detail is needed.

Read the Selected Operating Details and Cautionary Notes at the front of the Manual before using the CR7.

OV1. PHYSICAL DESCRIPTION

The CR7 features a modular, multiple processor design that provides precision measurement and control capability in a rugged, battery operated system. Control Module functions include real-time task initiation, measurement processing, data storage, telecommunications, and keyboard/display interaction. The I/O Module performs all analog and pulse signal measurement functions as well as the analog and digital control output functions. The I/O Module contains its own processor card, a precision analog interface card, and seven card slots which can accommodate any combination of I/O Cards. Sensor leads are connected to the I/O cards via screw terminals.

A maximum of four I/O modules, separated by up to 1,000 feet, may be connected to a single

Control Module in applications that require distributed measurement capability.

OV1.1 700X CONTROL MODULE

Contains the CPU card, with 24K of system PROM and 40K of RAM; the serial interface card for peripheral communication and connection of up to four I/O Modules; and the keyboard display card. Two slots are present for optional RAM expansion. The system's 2.5 Ahr lead-acid batteries and AC charging circuitry are also contained in this module.

The CS I/O 9-pin port provides connection to data storage peripherals, such as the SM192/716 Storage Module, and provides serial communication to computer or modem devices for data transfer or remote programming (Section 6). This 9 pin port does

NOT have the same pin configuration as the

OV-1

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

RS232 9 pin serial ports used on many computers.

The SDM terminals adjacent to the serial port allow connection to Synchronous Device for Measurement (SDM) peripherals. These peripherals include the SDM-INT8 Interval Timer, the SDM-SW8A Switch Closure Module, the SDM-CD16AC AC/DC Controller, and the SDM-OBDII Engine Controller Interface.

709 512K MEMORY CARD: This card provides RAM storage for an additional 262,126 Final Data values. Only one 709 card may be installed.

OV1.2 720 I/O MODULE

The processor card provides regulated power for analog and digital functions from the unregulated 12 volt supply. The analog interface card contains a 16-bit A/D-D/A converter, and a precision voltage reference. The standard I/O Module contains slots for 7 I/O Cards; the expanded Model 720XL contains 14 slots. All input and output connections to the I/O module are transient protected with spark gaps.

voltage with respect to the CR7 ground. Singleended channels are numbered sequentially, e.g., the HI and LOW sides of differential channels 2 are single-ended channels 3 and 4, respectively (Section 13.2).

724 PULSE COUNTER CARD: Provides 4 pulse counting channels for switch closures, low level AC cycles, or high frequency pulse signals.

725 EXCITATION CARD: There are 8 switched analog excitation channels. These supply programmable excitation voltages for resistive bridge measurements. The excitation channels are only switched on during the measurement. Only one is on at a time.

The two Continuous Analog Output (CAO) channels supply continuous output voltages, under program control, for use with strip charts, X-Y plotters, or proportional controllers.

The 8 Digital Control Ports (0 or 5 volt states) allow on-off control of external devices. These control ports have a very limited current output (5mA) and are used to switch solid state devices which in turn provide power to relay coils (Section 14.4).

The +12 volt and ground terminals provide a direct connection to the CR7 power supply.

723 ANALOG INPUT CARD: Contains 14 differential or 28 single ended inputs. Input ground terminals connect to a heavy copper bar, which reduces single ended measurement offsets to less than 5µV.

723-T ANALOG INPUT CARD WITH RTD:

Identical to the 723 Card except that a platinum resistance thermometer is mounted in the center of the terminal strip. The PRT provides a reference junction temperature for thermocouple measurement. The PRT measurement is accurate to ±0.1oC over a range of -40oC to +60oC.

The numbering on the terminals refers to the differential channels; i.e., the voltage on the HI input is measured with respect to the voltage on the Low input. When making single-ended measurements either the HI or the Low channel may be used independently to measure the

726 50 VOLT ANALOG INPUT CARD:

Provides 8 differential or 16 single ended inputs for full scale DC ranges of ±50 V and ±15V. Resolution is 1.66 millivolts on the ±50 V and

0.5 millivolts on the ±15 V range. The common mode range is ±50 volts.

OV1.3 ENCLOSURES AND CONNECTOR

OPTIONS ENC-7L ALUMINUM FRAME FOR

LABORATORY ENVIRONMENTS: 17" x 12" x

6"; provides a housing for benchtop use or a frame for attachment to a wall or a NEMA type enclosure.

ENC-7F ENVIRONMENTALLY SEALED FIBERGLASS ENCLOSURE: 20" x 13" x 10";

housing for harsh environments. Sensor leads enter via two ports fitted with 0.75" conduit bushings, and plugged with removable stoppers. The 1.040" hole size accommodates #14 shell size circular connectors.

OV-2

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

CR7

RELIEF VALVE

TTO

SS B

CAUTION

C G IN

LO N U

FIGURE OV1-1. CR7 Measurement and Control System

OV2. MEMORY AND PROGRAMMING

CONCEPTS

The CR7 must be programmed before it will make any measurements. A program consists of a group of instructions entered into a program table. The program table is given an execution interval which determines how frequently that table is executed. When the table is executed, the instructions are executed in sequence from beginning to end. After executing the table, the CR7 waits the remainder of the execution interval and then executes the table again starting at the beginning.

The interval at which the table is executed will generally determine the interval at which the sensors are measured. The interval at which data are stored is separate and may range from samples every execution interval to processed summaries output hourly, daily, or on longer or irregular intervals.

Figure OV2-1 represents the measurement, processing, and data storage sequence in the CR7 and shows the types of instructions used to accomplish these tasks.

OV2.1 INTERNAL MEMORY

The CR7 has 40,960 bytes of Random Access Memory (RAM), divided into five areas. The five areas of RAM are:

1. Input Storage - Input Storage holds the results of measurements or calculations. The *6 Mode is used to view Input Storage locations to check current sensor readings or calculated values. Input Storage defaults to 28 locations. Additional locations can be assigned using the *A Mode.

2. Intermediate Storage - Certain Processing Instructions and most of the Output Processing Instructions maintain intermediate results in Intermediate Storage. Intermediate storage is automatically accessed by the Instructions and cannot be accessed by the user. The default allocation is 64 locations. The number of locations can be changed using the *A Mode.

OV-3

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

ANALOG IPUTS

Input/Output Inst ruc tions

1. Volt (SE)

2. Volt (DIFF)

4. Ex-Del-Se

5. AC Half Br

6. Full Br

7. 3W Half Br

9. Full Br-Mex

11. Temp (107)

12. RH-(07)

13. Temp-TC SE

14. Temp-TC DIFF

17. Temp-Panel

+12

RTD

SDM PORTS

101 SDM-INT8 102 SDM-SW8 103 SDM-AO4 104 SDM-CD16 113 SDM-SIO4 115 Set SDM Clock 118 SDM-OBDII

720 I/O MODULE

ANALOG INTERFACE

726 50 VOLT INPUT

1234

H H H H

123456 7891011121314

HL HL HL HL HL HL HL HL HL HL HL HL HL HL

L1H L2H L3H L4H L5H L6H L7H L

724 PULSE COUNTER

MADE IN USA

CS I/O PORT

Telecommunications

Program Control Instructions 96 (Storage Module, Printer) 97 Initiate Telecommunications 98 Print Character

700X CONTROL MODULE

CAMPBELL SCIENTIFIC

LOGAN, UTAH

INC.

CR7 MEASUREMENT & CONTROL SYSTEM

I. D.

DATA

C3C2C1

+12

SDM

SERIAL I/O

PULSE INPUTS

Input/Output Inst ruc tions

3. Pulse

SWITCHED ANALOG OUT

1 2 3 4 5 6 7 8 1 2

EXCITATION OUTPUTS

Input/Output Inst ruc tions

4. Ex-Del-Se

5. AC Half Br

6. Full Br

7. 3W Half Br

9. Full Br-Mex

11. Temp (107)

12. RH (207)

22. Excit-Del

CONTINUOUS ANALOG OUT

725 EXCITATION

DIGITAL CONTROL OUT

1234 5678

CAO

21ANALOG OUT

ON OFF

AUX. POWER

CONTROL PORTS

Input/Output Inst ruc tions

20 Set Port

Program Control Instructions

83 If Case < F 86 Do 88 If x < = > y 89 If x < = > f 91 If flag, port 92 If Time

Command Codes: 4x Set port x high 5x Set port x low 6x Toggle port x 7x Puls e port x

123A

456B

789C

0#D

MADE IN USA

OV-4

FIGURE OV1-2. CR7 Wiring Panel and Associated Programming Instructions

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

INPUT/OUTPUT INSTRUCTIONS

Specify the conversion of a sensor signal to a data value and store it in Input Storage. Programmable entries specify: (1) the measurement type (2) the number of channels to measure (3) the input voltage range (4) the Input Storage Location (5) the sensor calibration constants used to convert the sensor output to engineering units

I/O Instructions also control analog outputs and digital control ports.

INPUT STORAGE

Holds the results of measurements or calculations in user specified locations. The value in a location is written over each time a new measurement or calculation stores data to the locations.

PROCESSING INSTRUCTIONS

Perform calculations with values in Input Storage. Results are returned to Input Storage. Arithmetic, transcendental and polynomial functions are included.

OUTPUT PROCESSING INSTRUCTIONS

Perform calculations over time on the values updated in Input Storage. Summaries for Final Storage are generated when a Program Control Instruction sets the Output Flag in response to time or events. Results may be redirected to Input Storage for further processing. Examples include sums, averages, max/min, standard deviation, histograms, etc.

Output Flag set high

FINAL STORAGE

Final results from OUTPUT PROCESSING INSTRUCTIONS are stored here for on-line or interrogated transfer to external devices (Figure OV5.1-1). When memory is full, new data overwrites the oldest data.

FIGURE OV2-1. Instruction Types and Storage Areas

INTERMEDIATE STORAGE

Provides temporary storage for intermediate calculations required by the OUTPUT PROCESSING INSTRUCTIONS; for example, sums, cross products, comparative values, etc.

OV-5

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

3. Final Storage - Final, processed values are stored here for transfer to printer, solid state Storage Module or for retrieval via telecommunication links. Values are stored in Final Storage only by the Output Processing Instructions and only when the Output Flag is set in the users program. The 18,336 locations allocated to Final Storage at power up is reduced if Input or Intermediate Storage is increased.

4. System Memory - used for overhead tasks such as compiling programs, transferring data, etc. The user cannot access this memory.

5. Program Memory - available for user programs entered in Program Tables 1 and 2, and Subroutine Table 3. (Sections OV3,

1.1)

The use of the Input, Intermediate, and Final Storage in the measurement and data processing sequence is shown in Figure OV2-1. While the total size of these three areas remains constant, memory may be reallocated between the areas to accommodate different measurement and processing needs (*A Mode, Section 1.5). The size of system and program memory are fixed.

3. OUTPUT PROCESSING INSTRUCTIONS (69-82, Section 11) are the only instructions which store data in Final Storage (destination). Input Storage (source) values are processed over time to obtain averages, maxima, minima, etc. There are two types of processing done by Output Instructions: Intermediate and Final.

Intermediate processing normally takes place each time the instruction is executed. For example, when the Average Instruction is executed, it adds the values from the input locations being averaged to running totals in Intermediate Storage. It also keeps track of the number of samples.

Final processing occurs only when the Output Flag is high. The Output Processing Instructions check the Output Flag. If the flag is high, final values are calculated and output. With the Average, accumulated totals are divided by the number of samples and the resulting averages sent to Final Storage. Intermediate locations are zeroed and the process starts over. The Output Flag, Flag 0, is set high by a Program Control Instruction which must precede the Output Processing Instructions in the user entered program.

OV2.2 CR7 INSTRUCTION TYPES

Figure OV2.1 illustrates the use of the three different instruction types which act on data. The fourth type, Program Control, is used to control output times and vary program execution. Instructions are identified by numbers.

1. INPUT/OUTPUT INSTRUCTIONS (126,101-104, Section 9) control the terminal strip inputs and outputs (the sensor is the source, Figure OV1-2), storing the results in Input Storage (destination). Multiplier and offset parameters allow conversion of linear signals into engineering units. The Control Ports and Continuous Analog Outputs are also addressed with I/O Instructions.

2. PROCESSING INSTRUCTIONS (30-66, Section 10) perform numerical operations on values located in Input Storage (source) and store the results back in Input Storage (destination). These instructions can be used to develop high level algorithms to process measurements prior to Output Processing (Section 10).

4. PROGRAM CONTROL INSTRUCTIONS (85-98, Section 12) are used for logic decisions and conditional statements. They can set flags, compare values or times, execute loops, call subroutines, conditionally execute portions of the program, etc.

OV2.3 PROGRAM TABLES AND THE

EXECUTION AND OUTPUT INTERVALS

Programs are entered in Tables 1 and 2. Subroutines, called from Tables 1 and 2, are entered in Subroutine Table 3. The size of each table is flexible, limited only by the total amount of program memory. If Table 1 is the only table programmed, the entire program memory is available for Table 1.

Table 1 and Table 2 have independent execution intervals, entered in units of seconds with an allowable range of 0.0125 to 6553 seconds. Intervals shorter than 0.1 seconds are allowed only in Table 1. Subroutine Table 3 has no execution interval; subroutines are only executed when called from Table 1 or 2.

OV-6

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

Table 1. Execute every x sec.

0.0125 < x < 6553

Instructions are executed sequentially in the order they are entered in the table. One complete pass through the table is made each execution interval unless program control instructions are used to loop or branch execution.

Normal Order: MEASURE PROCESS CHECK OUTPUT COND. OUTPUT PROCESSING

FIGURE OV2-2. Program and Subroutine Tables

OV2.3.1 THE EXECUTION INTERVAL

The execution interval specifies how often the program in the table is executed, which is usually determined by how often the sensors are to be measured. Unless two different measurement rates are needed, use only one table. A program table is executed sequentially starting with the first instruction in the table and proceeding to the end of the table.

Each instruction in the table requires a finite time to execute. If the execution interval is less than the time required to process the table, the CR7 overruns the execution interval, finishes processing the table and waits for the next execution interval before initiating the table. When an overrun occurs, decimal points are shown on either side of the G on the display in the LOG mode (*0). Overruns and table priority are discussed in Section 1.1.

Table 2. Execute every y sec.

0.1 < y < 6553

Table 2 is used if there is a need to measure and process data on a separate interval from that in Table 1.

Table 3. Subroutines

A subroutine is executed only when called from Table 1 or 2.

Subroutine Label Instructions End

OV2.3.2 THE OUTPUT INTERVAL

The interval at which output occurs is independent from the execution interval, other than the fact that it must occur when the table is executed (i.e., a table cannot have a 10 minute execution interval and output every 15 minutes).

A single program table can have many different output intervals and conditions, each with a unique data set (output array). Program Control Instructions are used to set the Output Flag which determines when output occurs. The Output Processing Instructions which follow the instruction setting the Output Flag determine the data output and its sequence. Each additional output array is created by another Program Control Instruction setting the Output Flag high in response to an output condition, followed by Output Processing Instructions defining the data set to output.

OV3. PROGRAMMING THE CR7

A program is created by keying it directly into the datalogger or on a PC using the PC208 or PC208W Datalogger Support Software program EDLOG. This manual describes direct interaction with the CR7. Work through the direct programming examples in this overview before using EDLOG and you will have the basics of CR7 operation as well as an appreciation for the help provided by the software. Section OV3.5 describes options for loading the program into the CR7.

OV-7

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

OV3.1 FUNCTIONAL MODES

User interaction with the CR7 is broken into different functional MODES, (e.g., programming the measurements and output, setting time, manually initiating a block data transfer to Storage Module, etc.). The modes are referred to as Star (*) Modes since they are accessed by first keying *, then the mode number or letter. Table OV3.1 lists the CR7 Modes.

TABLE OV3-1. * Mode Summary

Key Mode

*0 LOG data and indicate active Tables *1 Program Table 1 *2 Program Table 2 *3 Program Table 3, subroutines only *4 Enable/disable printer output *5 Display/set real time clock *6 Display/alter Input Storage data, toggle

flags *7 Display Final Storage data *8 Final Storage data transfer to cassette

tape *9 Final Storage data transfer to printer *A Memory allocation/reset *B Signature test/PROM version *C Security *D Save/load Program

TABLE OV3-2. Key Description/Editing

Functions

Key Action

0-9 Key numeric entries into display * Enter Mode (followed by Mode Number) A Enter/Advance B Back up C Change the sign of a number or index

an input location to loop counter D Enter the decimal point # Clear the rightmost digit keyed into the

display #A Advance to next instruction in program

table (*1, *2, *3) or to next output array

in Final Storage (*7) #B Back up to previous instruction in

program table or to previous output

array in Final Storage #D Delete entire instruction

OV3.3 PROGRAMMING SEQUENCE

In routine applications, sensor signals are measured, processed over some time interval, and the results are stored in Final Storage. A generalized programming sequence is:

1. Enter the execution interval, determined by

the desired sensor scan rate.

OV3.2 KEY DEFINITION

Keys and key sequences have specific functions when using the CR7 keyboard or a terminal/computer in the remote keyboard state (Section 5). Table OV3.2 lists these functions. In some cases, the exact action of a key depends on the mode the CR7 is in and is described with the mode in the manual.

2. Enter the Input/Output Instructions required

to measure the sensors.

3. Enter any Processing Instructions required

to get the data ready for Output Processing.

4. Enter a Program Control Instruction to test

the output condition and Set the Output Flag when the condition is met. For example, use Instruction 92 to output based on time, 86 to output each time the table is executed, and 88 or 89 to compare input values. This instruction must precede the Output Processing Instructions.

5. Enter the Output Processing Instructions to

store processed data in Final Storage. The order in which the data are stored is determined by the order of the Output Processing Instructions in the table.

6. Repeat steps 4 and 5 for output on different

intervals or conditions.

OV-8

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

OV3.4 INSTRUCTION FORMAT

Instructions are identified by an instruction number. Each instruction has a number of parameters that give the CR7 the information it needs to execute the instruction.

The CR7 Prompt Sheet has the instruction numbers in red, with the parameters briefly listed in columns following the description. Some parameters are footnoted with further description under the "Instruction Option Codes" heading.

For example, Instruction 73 stores the maximum value that occurred in an Input Storage Location over the output interval. The instruction has three parameters (1) REPetitionS, the number of sequential Input Storage locations on which to find maxima, (2) TIME, an option of storing the time of occurrence with the maximum value, and (3) LOC the first Input Storage Location operated on by the Maximum Instruction. The codes for the TIME parameter are listed in the "Instruction Option Codes".

The repetitions parameter specifies how many times an instruction's function is to be repeated. For example, four 107 thermistor probes, wired to single-ended channels 1 through 4, are measured using a single Instruction 11, Temp107, with four repetitions. Parameter 2 specifies the input channel of the first thermistor (channel 1) and parameter 4 specifies the Input Storage Location in which to store measurements from the first thermistor. If Location 5 were used, the temperature of the thermistor on channel 1 would be stored in Input Location 5, the temperature from channel 2 in Input Location 6, etc.

Detailed descriptions of the instructions are given in Sections 9-12.

OV3.5 ENTERING A PROGRAM

Programs are entered into the CR7 in one of four ways:

1. Keyed in using the CR7 keyboard.

b. Stored/loaded from SM192/716 Storage

Module

3. Loaded from Storage Module or internal PROM (special software) upon power-up.

A program is created by keying it directly into the datalogger as described in the following Section, or on a PC using the PC208 Datalogger Support Software.

PC208 Software programs are used to develop and send programs to the CR7. Program files developed can be downloaded directly to the CR7 via direct wire, telephone, or Radio Frequency (RF).

Programs on disk can be copied to a Storage Module. Using the *D Mode to save or load a program from a Storage Module is described in Section 1.8.

If the SM192/716 Storage Module is connected when the CR7 is powered-up, the CR7 will automatically load program number 8, provided that a program 8 is loaded in the Storage Module (Section 1.8).

It is also possible (with special software) to create a PROM (Programmable Read Only Memory) that contains a datalogger program. With this PROM installed in the datalogger, the program will automatically be loaded and run when the datalogger is powered-up, requiring only that the clock be set.

OV4. PROGRAMMING EXAMPLE

The best way to become acquainted with the CR7 is to program it and make some measurements. If your CR7 contains either a 723 or 723-T Analog Input card, a short copper-constantan thermocouple (TC) should be connected to channel 5. In this example, you will program the CR7 to sample the thermocouple temperature. If you have not purchased the 723-T with a Resistive Temperature Device (RTD) to measure the TC reference junction temperature, a "dummy" reference temperature will be used.

2. Loaded from a pre-recorded listing using the *D Mode. There are two types of storage/input:

a. Stored on disk/sent from computer

(PC208 software).

OV-9

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

Tables OV3-1 and OV3-2 summarize the Keyboard Commands and Control Modes used to program the CR7, monitor Input and Final Storage and control data output to peripherals. The instructions, and their associated parameters, are the CR7's programming steps and are used to build the CR7's program. It is not necessary to understand all the commands to proceed with this programming exercise. It is helpful to find the example's instructions on the CR7 Prompt Sheet provided with this manual. As you become familiar with programming the CR7, you will find that the Prompt Sheet or the PC208 program EDLOG has all the information you need to write your program. By following along on the Prompt Sheet as you proceed with this exercise, you will learn how to use it to write your own programs.

OV4.1 MEASUREMENT

To make a thermocouple temperature measurement, the CR7 must know the temperature of the reference junction. The CR7 takes the reference temperature, converts it to the equivalent TC voltage, adds the measured TC voltage and converts the sum to temperature through a polynomial fit to the TC output curve. In this example, the reference junction is at the Analog Input Card. Its temperature is measured with Instruction 17, Panel Temperature. If you have an Analog Input Card with RTD, check to see which number is assigned to it. A tag labeled RTD is on the left hand side and the card number is on the right hand side of the Analog Input Card. If the RTD card is not card 1, you must enter the correct card number as Parameter 1 of Instruction 17. If you do not have an Analog Input Card with RTD, you will omit Instruction 17 from the Program and enter a "dummy" reference temperature after the Program is compiled.

The thermocouple temperature measurement is made using Instruction 14 (differential voltage measurement of TC) on differential channel 5. When using a copper-constantan thermocouple, the copper lead is connected to the high input of a differential channel and the constantan lead is connected to the low side. The channel numbering printed on the Analog Input Cards refers only to differential channels.

Either the high or low side of a differential channel may be used for single ended measurements. (Each side is counted when assigning single ended channel numbers; e.g., the high side of differential channel 8 is single ended channel 15 and the low side is single ended channel 16).

The first parameter in Instruction 14 is the number of times to repeat the measurement: 1 is entered because only one thermocouple is measured. If more thermocouple measurements were desired, the copper leads would be connected to the high sides of consecutive differential channels, the constantan leads to the low sides and the number of repetitions entered in Parameter 1 would equal the number of thermocouples.

Parameter 2 is the voltage range to use when making the measurement. The output of a copper-constantan thermocouple is approximately 40 microvolts per oC difference in temperature between the two junctions. The +5000 uV scale will provide a range of +5000/40 = +125 oC (i.e., this scale will not overrange as long as the measuring junction is within 125 oC of the panel temperature). The resolution of the +5000 uV range is 166 nV or 0.004 oC.

Parameter 3 is the Input Card number and Parameter 4 is the channel on which to make the first measurement. If more than one thermocouple is measured, the CR7 will automatically advance through the channels and on to the next card if necessary. Similarly, Parameter 7 is the Input Storage Location in which to store the first measurement; e.g., if there are five repetitions and the first measurement is stored in location 3, the final measurement will be stored in location 7.

Parameter 6 is the Input Storage location in which the reference temperature is stored, and Parameters 8 and 9 are the multiplier and offset to apply to the temperature value. A multiplier of 1 and an offset of 0 give the result in oC, a multiplier of 1.8 and an offset of 32 give the result in oF.

Now that you have some idea of what you are telling the CR7 by entering the parameters, we will proceed with programming the CR7.

OV-10

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

TABLE OV4-1. Thermocouple Measurement Programming Example

TURN ON THE POWER SWITCH AND PROCEED AS FOLLOWS:

Display ID:Data Key

HELLO 01

00:00 01:0.0000

01:P00 01:00

02:0000

02:P00 01:00 02:00 03:00 04:00 05:00 06:0000 07:0000 08: 0.0000 09: 0.0000

03:P00

Display ID:Data Key Description

:0064

01:00

01:2

-------Users without RTD omit next Instruction------

01:P17

01:1

02:1

-------Users without RTD continue here-------

Instruction Location Number will be 1 less (i.e., 01:P00)

02:P14

01:1

02:2

03:1

04:5

05:1

06:1

07:2

08:1 09:0.0000

A A

A A A A A A A A A A

The number after "HELLO" will count up as memory is checked. If you have a 512K Memory Card, this can take a long time; key # to abort the test. The result of the CPU board memory check is then displayed (Sect. 1.5) Enter Program Table 1, advance to Execution Interval Enter 2 second Execution Interval advance to first instruction

Measure Panel Temp., advance to first Parameter RTD in input card #1, if RTD card other than #1, enter correct card # Store temp in location 1

TC temp., differential meas. 1 repetition Range code (5000uV, slow) Input card #1 Input channel of 1st TC TC type (copper-constantan) Reference temp. is in location 1 Store TC temp. in location 2 Multiplier of 1 No offset entered (offset=0), advance to next instruction Exit Table 1

00:00

The CR7 is now programmed to measure the thermocouple temperature and to store the result in Input Storage Location 2. The colon between the ID and Data fields blinks each time Table 1 is executed, every 2 seconds in this example. If you do not have an RTD, the "reference temperature" is 0.0 and the value stored in Location 2 is the difference in temperature between the panel and the thermocouple. The *6 Mode can be used to monitor the values in the Input Storage and to change the value of the dummy reference temperature.

:LOG 1

Enter *0 Mode, compile table

OV-11

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

TABLE OV4-2. Using *6 Mode to Observe Example TC Measurements

(User with Model 723-T RTD Card)

Display ID:Data Key

:LOG 1

00:00

Display ID:Data Key

:LOG 1

:0.0000

00:00

TABLE OV4-3. Using *6 Mode to Observe Example TC Measurements

Display ID:Data Key Description

06:0000 01:21.234 02:22.433 01:21.199

:LOG 1

(User with Model 723 Card, No RTD)

Display ID:Data Key Description

06:0000 01:0.0000 02:2.9533 01:0.0000 :20 01:20.000 02:22.866

:LOG 1

A A B

A A

Enter *6 Mode, advance to first location Panel temp is 21.234 oC, advance to location 2 TC temp is 22.433 oC, backup to location 1 Panel temp is now 21.199 oC Return to *0 Mode

Enter *6 Mode, advance to first location Reference temp is 0.0oC, advance to location 2 TC "temp" is 2.9533 C, backup to location 1 Setup to change stored value Store 20 in location 1 Advance to location 2 The TC temp in location 2 using a reference temperature of 20 Return to *0 Mode

You can advance through Input Storage by keying in the advance command, A, or backup by keying in the backup command, B. The Input Location you are observing is shown on the left in the display ID field. The temperature data stored in the Input locations are updated every 2 seconds, each time Table 1 is executed. Verify this by changing the temperature of the thermocouple (hold it in your fingers) while monitoring the proper Input Location.

It is possible to go directly to a specific Input Storage location by entering the *6 Mode and keying in the desired location before keying A. A similar utility is available in other Modes.

OV4.2 OUTPUT

In the following example instructions are appended to Table 1 to output the time and the average temperatures to Final Storage every 5 minutes.

OV-12

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

TABLE OV4-4. Example Programming to Obtain Five Minute Averages

Display ID:Data Key

00:00 01:00

03:P00 01:0000 02:0000 03:00

04:P00 01:0000 05:P00 01:00 02:0000

06:P00 00:00

05:00 05:0000

05:00:21 13:24:01 : LOG 1

10 77

10 71

85 11

1324

Display ID:Data Key Description

1 3

0 5

2 1

: LOG 1 01:00 01:3

03:P92 01:0 02:5 03:10

04:P77 :10 05:P71 01:2 02:1

:00:21:32 05:85 05:11

05:13:24

A A A A

A A A A A

A A A

Program Table 1 Advance to 3rd Instruction location (Key in 2 if Instruction 17 was not entered, Instruction Location Number will be 1 less than shown in table)

Enter If Time Instruction Enter 0 minutes into interval Enter 5 minute time interval Set output Flag 0

Enter Output Time Instruction Code for HR:MIN Enter Average Instruction 2 repetitions Location of 1st input data to be averaged

Exit Table 1 Enter *5 Mode to set clock (the clock will be running)

Enter Year Enter Julian day (January 11 assumed in this example) Enter Hours:Minutes (24 hour time, 1:24 PM assumed in this example) Exit *5 Mode, compile Table 1, commence logging data

The CR7 is now programmed to sample the panel and thermocouple temperatures every 2 seconds and to output the time and the average temperatures to Final Storage every 5 minutes. Each Output Array sent to Final Storage will consist of 4 data values. The first value will be an output identifier which gives the number of the Table which caused the output, and the instruction location number of the instruction which set the output flag. The second value will be the time, and the third and fourth values will be the average temperatures of the I/O Module and the thermocouple. Values stored in Final Storage can be viewed using the *7 Mode. Table 1.2-5 shows an example of the use of the *7 Mode, it is assumed that the CR7 has been logging data for 8 minutes since the time was set in the previous example.

OV-13

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

TABLE OV4-5. Using *7 Mode to View Values in Final Storage

Display ID:Data Key

:LOG 1 00:00 01:0103.

02:1325. 03:22.57 04:23.43 01:0103. 02:1330. 03:22.61 00:00

OV4.3 EDITING AN EXISTING PROGRAM

When editing an existing program in the CR7, entering a new instruction inserts the instruction; entering a new value for an instruction parameter replaces the previous value.

To insert an instruction, enter the program table and advance to the position where the instruction is to be inserted (i.e., P in the data portion of the display), key in the instruction number, and then key A. The new instruction will be inserted at that point in the table, advance through and enter the parameters. The Instruction that was at that point and all instructions following it will be pushed down to follow the inserted instruction.

An instruction is deleted by advancing to the instruction number (P in display) and keying #D (Table OV3-2).

To change the value entered for a parameter, advance to parameter and key in the correct value then key A. Note that the new value is not entered until A is keyed.

OV4.4 EDLOG PROGRAM LISTING

The examples in the rest of this manual use program listings generated by EDLOG, the datalogger Program Editor for the PC (PC208(W) Software). The EDLOG listing does not show the CR7 display or the "A" keystrokes used to enter data. The EDLOG listing for the previous example is given in Table OV4-6.

Display ID:Data Key Description

7007:9.0000

:LOG 1

Enter *7 Mode. The DSP is at Final Storage location 9, advance to first data value

Output identifier: users who did not enter Instruction 17 will see 01: 0102 because the output flag is set by the second instruction in Table 1

Time

Average panel temp for readings between 1:24 and 1:25 P.M.

Average thermocouple temp.

Output identifier

Time

Average panel temp for readings between 1:25 and 1:30 P.M. Enter *0 Mode

TABLE OV4-6. EDLOG Listing of Example

Program

* 1 Table 1 Programs

01: 2 Sec. Execution Interval

01: P17 Panel Temperature

01: 1 IN Card 02: 1 Loc :

02: P14 Thermocouple Temp (DIFF)

01: 1 Rep 02: 2 5000 uV slow Range 03: 1 IN Card 04: 5 IN Chan 05: 1 Type T (Copper-Constantan) 06: 1 Ref Temp Loc 07: 2 Loc [:TC Temp ] 08: 1 Mult 09: 0 Offset

03: P92 If time is

01: 0 minutes into a 02: 5 minute interval 03: 10 Set high Flag 0 (output)

04: P77 Real Time

01: 10 Hour-Minute

05: P71 Average

01: 2 Reps 02: 1 Loc

OV-14

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

OV5. DATA RETRIEVAL OPTIONS

There are several options for data storage and retrieval. These options are covered in detail in Sections 2, 4, and 5. Figure OV5-1 summarizes the various possible methods.

Regardless of the method used, there are three general approaches to retrieving data from a datalogger.

1. On-line output of Final Storage data to a peripheral storage device. On a regular schedule, that storage device is brought back to the office/lab where the data is transferred to the computer. Another storage device is usually taken into the field and exchanged for the one which is retrieved so that data collection can continue uninterrupted.

2. Bring a storage device to the datalogger and transfer all the data that has accumulated in Final Storage since the last visit.

3. Retrieve the data over some form of telecommunications link, that is, Radio Frequency (RF), telephone, short haul modem, multi-drop interface, or satellite. The PC208 software automates this process.

Regardless of which method is used, the retrieval of data from the datalogger does NOT erase those data from Final Storage. The data remain in the ring memory until:

• they are written over by new data

(Section 2.1)

• memory is reallocated (Section 1.5)

• the power to the datalogger is turned

off.

Table OV5-1 lists the instructions used with the various methods of data retrieval.

TABLE OV5-1. Data Retrie val Methods and Related Instructions

Storage Printer, other Telecommunications Module Serial Device

Inst. 96, Inst. 96, 98 Inst. 97 *4 *4 *9 *9 (Telecommunications Commands) *D *D

TABLE OV5-2. Data Retrieval Sections in Manual

Topic Section in Manual Instr. 96 4.1, 12

Instr. 97 12 *4 4.1 *8 4.2 *9 4.2 *D 1.8 Storage Module 4.3 Telecommunications 5

(RF, Phone, Short Haul, SC32A)

OV-15

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

+12

720 I/O MODULE

ANALOG INTERFACE

726 50 VOLT INPUT

1234 H H H H

1 2 3 4 5 6 7 8 9 10 11 12 13 14

HL HL HL HLHL HL HLHL HLHL HLHL HL HL

RTD

SWITCHED ANALOG OUT

1 2 3 4 5 6 7 8 1 2

L1HL2HL3HL4HL5HL6HL7HL

724 PULSE COUNTER

CONTINUOUS ANALOG OUT

725 EXCITATION

700X CONTROL MODULE

MADE IN USA

CAMPBELL SCIENTIFIC

LOGAN, UTAH

INC.

SERIAL I/O

CR7 MEASUREMENT & CONTROL SYSTEM

I. D.

DATA

DIGITAL CONTROL OUT

1234 5678

123A

456B

789C

0#D

AUX. POWER

OFF

MADE IN USA

Display

Storage Module

RS-232

Interface

Card Storage

Module

Multidrop

Modem

Shorthaul

Modem

RF Modem Phone

Transceiver

Card Storage

Module

RS-232

Interface

Direct

RS-232

Interface

Multidrop

Modem

RS-232

Interface

Logger Time 00:03:54

= Graph enter/exit

= Re-scale

Flags

= Incr. auto exponent

Ports

= Decr. auto exponent

H=Help

100

200

300

400

500

600

700

800

900

Shorthaul

Modem

V = View save to file F1. . F8 = Toggle flags P1. . P6 = Toggle ports C = Collect data

SOLAR

TEMP C

RH %

Scale = Auto

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

2100

2200

2300

Transceiver

RF Base

Station

FIGURE OV5-1. Data Retrieval Hardware Options

Modem

Phone

Modem

Satellite Interface

Satellite

Ground Station

OV-16

OV6. SPECIFICATIONS

Electrical specifications are valid for over a -25° to +50°C range unless otherwise specified.

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

Analog Inputs

(723T or 723 Card specifications below;

726 ±50 V Card specifications discussed in

System Description

Voltage Measurement Types: Single-ended or

differential.

Range and Resolution: Ranges are software

selectable on any input channel.

Full Scale Resolution

Input Range (mV) Differential Single-ended

±5000 166 µV 333 µV ±1500 50 µV 100 µV

±500 16.6 µV 33.3 µV ±150 5 µV10µV

±50 1.66 µV 3.33 µV ±15 500 nV 1000 nV

±5 166 nV 333 nV ±1.5 50 nV 100 nV

Accuracy of Voltage Measurements:

Differential: ±0.02% FSR (±0.01%, 0-40°C)

(e.g. ±0.02% FSR = ±2.0 mV for ±5 V range)

Positive single-ended: ±0.02% FSR

(±0.01%, 0-40°C) ±5 µV

Negative single-ended: ±0.03% FSR

(±0.015%, 0-40°C) ±5 µV

Input Sample Rates: Fast A/D conversions are

integrated over 250 µs. Slow A/D conversions are integrated over 16.67 ms for 60 Hz AC rejection or optionally, 20.0 ms for 50 Hz AC rejection. Differential measurements include two conversions, one with reversed input polarity, to reduce thermal offset and common mode errors. The following intervals do not include the self-calibration measurement which occurs once per instruction.

Fast Single-ended 2.9 350 Fast Differential 4.7 250 Slow Single-ended 22.0 43 Slow Differential 43.0 30 Fast Differential (TC) 7.9 250

Common Mode Range: ±5 V Common Mode Rejection: > 140 dB (DC to 100 Hz) Normal Mode Rejection: 70 dB (60 Hz with

slow differential measurement)

Input Current: 100 pA max Input Current Noise: 9 pA RMS (slow differential) Input Resistance: 2.5 GΩ typical Sustained Input Voltage without Damage:

≤ ±16 VDC

)

Input sample Typical input

rates noise

ms/channel nV/RMS

Pulse Counters

(724 Card)

Pulse Counters per Card: 4 Maximum Counts per Interval: 32,767 (with

overrange detection)

Modes: Programmable modes are switch

closure, high frequency pulse, and low level AC.

Switch Closure Mode

Minimum Switch Closed Time:1 ms Minimum Switch Open Time:4 ms Maximum Bounce Time:1.4 ms open without

being counted.

High Frequency Pulse Mode

Minimum Pulse Width: 2 µs Maximum Input Frequency: 250 kHz Voltage Thresholds: The count is incremented

when the input voltage changes from below

1.5 V to above 3.5 V.

Maximum Input Voltage: ±20 V

Low Level AC Mode

This mode is used for counting the frequency

of low voltage, sine wave signals. Input Hysteresis: 11 mV Maximum AC Input Voltage (RMS): 20 V Frequency Range:

Minimum AC Input Voltage Range (Hz)

(mV RMS)

15 1 to 100 25 1 to 1,000 50 1 to 3,000

160 1 to 10,000

Digital Control Outputs

(725 Card) Each card includes 8 digital control outputs.

Output Voltages (no load):

High: 5.0 V ±0.1 V Low: < 0.1 V

Output Resistance: 400 Ω

Analog Outputs

(725 Card) Each card contains 8 switched and 2 continuous

analog outputs.

Switched: Provides a precision voltage for

resistance measurement, then switches off (high impedance). Only one switched output can be active at a time.

Continuous: A preset voltage is held until

updated. Voltage degrades 0.17 mV every 7 seconds. All continuous analog outputs (and digital control ports) can be active simultaneously.

Range: ±5 V Resolution: 166 µV Accuracy: Same as voltage measurements. Output Current: 25 mA at ±5 V, 50 mA at ±2 V

Resistance and Conductivity Measurements

(Combination of 723 and 725 Cards) Accuracy: ±0.01% of full scale bridge output

provided the matching bridge resistors are not the limiting factor.

Measurement Types: 6-wire and 4-wire full

bridge, 4-wire, 3-wire, and 2-wire half bridges. High accuracy, low impedance bridge measurements are made ratiometrically with dual polarity measurements of excitation and output to eliminate thermal emfs. AC resistance and conductivity measurements use a 750 µs excitation pulse with the signal integration occurring over the last 250 µs. An equal duration pulse of opposite polarity is applied for ionic depolarization.

Transient Protection

All input and output connections to the I/O Module are protected using spark gaps that are rated to 10,000 A. The spark gaps are connected directly to a heavy copper bar on each input card with no more than 2 inches of 20 AWG copper wire.

Control Module

Processor: Hitachi 6303 Memory: 24K ROM; 40K RAM, 709 Card

provides an additional 512K RAM.

Data Storage: 18.8K values, standard;280K

values, expanded.

Display: 8 digit LCD (0.5” digits). Peripheral Interface: 9-pin, D-type connector

on the Control Module panel for connection to storage module, card storage module, multidrop interface, modem, printer, or RS-232 adapter. Baud rates selectable at 300, 1200, 9600, and 76,800.

I/O Module Interface: Optically isolated current

loops allow connection of up to 4 I/O Modules. I/O Modules can be separated from the Control Module by up to 1,000 feet.

Clock Accuracy: ±1 minute per month. Maximum Program Execution Rate: System

tasks can be initiated in sync with real-time up to 80 Hz.

System Power Requirements

Voltage: 9.6 to 15 VDC Typical Current Drain: 3.5 - 6 mA (minimum

system) quiescent, 16 mA during processing, 100 mA during analog measurement.

Internal Batteries: Sealed rechargeable with

2.5 Ahr capacity per charge.

Charging Circuit: Requires DC or rectified AC

voltage from 15 to 25 V. Thermal compensation is included to optimize charging voltage according to ambient temperature.

External Batteries: Any 12 V external battery

can be a primary power source; internal batteries provide a backup while the external batteries are changed.

Operation from AC Sources: An AC operated

battery charger is included with the enclosure to maintain full charge on the batteries where AC power is available. In the event of power failure, the internal batteries will keep the system operational for up to 5 days in most applications.

Physical Specifications

Size: ENC 7L 17” x 12” x 6”

Weight: ~40 lbs (ENC 7F with 700X, 720, &

ENC 7F 20” x 13” x 10” ENC 7XL 19” x 19” x 10”

seven I/O cards).

Warranty

Three years against defects in materials and workmanship.

OV-17

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

This is a blank page.

OV-18

SECTION 1. FUNCTIONAL MODES

1.1 PROGRAM TABLES - 1, 2, AND *3 MODES

Data acquisition and processing functions are controlled by instructions contained in program tables. Programming can be separated into two tables, each having its own programmable execution interval. A third table is available for programming subroutines which may be called by instructions in Tables 1 or 2 or by a special interrupt. The *1 and *2 Modes are used to access Tables 1 and 2. The *3 Mode is used to access Subroutine Table 3.

When a program table is first entered, the display shows the table number in the ID Field and 00 in the Data Field. Press A and the CR7 will advance to the execution interval. If there is an existing program in the table, enter an instruction location number prior to A and the CR7 will advance directly to the instruction (e.g., 5 will advance to the fifth instruction in the table).

1.1.1 EXECUTION INTERVAL

The execution interval is entered in units of seconds as follows:

0.0125 .... 0.1 seconds, in multiples of 0.0125

0.1 .....6553 seconds, in multiples of 0.1 second

Intervals less than 0.1 second are allowed in Table 1 only. Execution of the table is repeated at the rate determined by this entry. The table will not be executed if 0 is entered. Values less than 0.1 are rounded to the nearest even multiple of 0.0125. If the Interval is 0.1 or greater, the CR7 will not allow entry of digits beyond 0.1.

The rate at which the CR7 can execute a given table must not be confused with the sample rates for the measurements contained within the table. When a table is executed and a measurement is made, the Control Module instructs the I/O Module which measurement to make and how many times to repeat it on successive channels. The I/O module then repeats the measurement as fast as possible and stores the data until the Control Module is ready for it. The Control Module takes the raw data and scales it as required by the instruction initiating the measurement. The next instruction

in the table is not executed until the scaling is completed. The maximum sample rate for a measurement is the rate at which the I/O Module can make a number of measurements specified by a single input instruction. Because the sample rate does not include the processing time required to scale the measurements into engineer units, the execution time of an instruction will be greater than the sample rate for the measurement specified by the instruction. The execution times for the instructions are given in Section 3.9.

The throughput rate is the rate at which a measurement can be made and the resulting value stored in Final Storage. The maximum throughput rate for fast single ended measurements is approximately 310 measurements per second.

If the specified execution interval for a table is less than the time required to process that table, the CR7 overruns the execution interval, finishes processing the table and waits for the next occurrence of the execution interval before again initiating the table (i.e., when the execution interval is up and the table is still executing, that execution is skipped). Since no advantage is gained in the rate of execution with this situation, it should be avoided by specifying an execution interval adequate for the table processing time.

NOTE: Whenever an overrun occurs, decimal points are displayed on both sides of the sixth digit of the CR7 display (e.g., L O.G. in the *0 Mode).

When the Output Flag is set high, extra time is consumed by final output processing. It may be acceptable if the execution interval is exceeded at this time. For example, suppose it is desired to measure every 0.1 seconds and output processed data every ten minutes. The table requires less than 0.1 seconds to process except when output occurs (every 10 minutes). With final output processing the time required is one second. With the execution interval set at

0.1 seconds, and a one second lag between samples once every 10 minutes, 10 measurements out of 6000 (.17%) are missed: an acceptable statistical error for most populations.

1-1

SECTION 1. FUNCTIONAL MODES

1.1.2 SUBROUTINES

Table 3 is used to enter subroutines which may be called with Program Control Instructions in Tables 1 and 2 or other subroutines. The group of instructions which form a subroutine starts with Instruction 85, Label Subroutine, and ends with Instruction 95, End. (Section 12)

1.1.3 TABLE PRIORITY/INTERRUPTS

Table 1 execution has priority over Table 2. If Table 2 is being executed when it is time to execute Table 1, Table 2 will be interrupted. After Table 1 is completed, Table 2 resumes at the point of interruption. If the execution interval of Table 2 coincides with Table 1, Table 1 will be executed first, followed by Table 2.

Interrupts by Table 1 are not allowed in the middle of a measurement or while output to Final Storage is in process (the Output Flag, flag 0, is set high). The interrupt occurs as soon as the measurement is completed or flag 0 is set low.

1.1.4 COMPILING A PROGRAM

1.2 SETTING AND DISPLAYING THE CLOCK - *5 MODE

The *5 Mode is used to display time or change the year, day of year, or time. When *5 is pressed, the current time is displayed. The time parameters displayed in the *5 Mode are given in Table 1.2-1.

The CR7 powers-up with hours and minutes set to 0 and the day and year set for the date that the PROMs were first released by Campbell Scientific. To set the year, day, or time, enter the *5 Mode and advance to display the appropriate value. Key in the desired number and enter the value by pressing A. When a new value for hours and minutes is entered, the seconds are set to zero and current time is again displayed. To exit the *5 Mode, press *. When the time is changed, a partial recompile is done automatically to resynchronize program execution with real time. The resynchronization process can change the interval of a pulse rate measurements for one execution interval as explained in the PULSE COUNT Instruction 3 in Section 9.

When a program is entered, or any changes are made in the *1, *2, *3, *4, *A, or *C Modes, the program must be compiled before it starts running. The compile function checks for programming errors and optimizes program information for execution. If errors are detected, the appropriate error codes are indicated on the Display (Section 3.10). Compiling occurs when the *0 , *6, or *B Modes are entered and prior to saving a program listing in the *D Mode. Compiling only occurs after a program change has been made; subsequent use of any of these Modes does not cause compiling.

Compiling with the *0, *B, or *D Mode sets all output ports and flags low and resets the timer (Instruction 26) and all data in Input and Intermediate Storage to ZERO.

When the *6 Mode is used to compile data in Input Storage, the state of flags, control ports, and the timer are UNALTERED. Compiling always zeros Intermediate Storage.

TABLE 1.2-1. Sequence of Time Parameters

in *5 Mode

Display

Key ID:DATA Description

*5 :HH:MM:SS Display current time A 05:XX Display/enter year A 05:XXXX Displ ay/enter day of y ear A 05:HH:MM: Display/enter

hours:minutes

1.3 DISPLAYING AND ALTERING INPUT MEMORY OR FLAGS - *6 MODE

The *6 Mode is used to display or change Input Storage values and to toggle and display user flags. If the *6 Mode is entered immediately following any changes in program tables or the *4 Mode, the programs will be compiled and execution will begin.

When the *6 Mode is used to compile data values contained in Input Storage, the state of flags, control ports, and the timer are UNALTERED. Compiling always zeros Intermediate Storage.

1-2

SECTION 1. FUNCTIONAL MODES

TABLE 1.3-1. *6 Mode Commands

Key Action

A Advance to next location or enter new

value B Back-up to previous location C Change value in displayed location(Key

C, then value, then A) D Display/alter user flags # Display current location and allow a

location no. to be keyed in, followed by

A to jump to that location * Exit *6 Mode

1.3.1 DISPLAYING AND ALTERING INPUT STORAGE

When *6 is keyed, the display will read "06:0000". One can advance to view the value stored in Input Storage location 1 by pressing A. To go directly to a specific location, key in the location number before keying A. For example, to view the value contained in Input Storage location 20, key in *6 20 A. The ID portion of the display shows the last two digits of the location number. If the value stored in the location being monitored is the result of a program instruction, the value will be updated each time the instruction is executed.

Values may be entered into input locations using the change command, C. While viewing the contents of the input location in which the value is to be entered, key C; the location number in the ID field will disappear. Key in the desired value and then enter it by pressing A.

If an algorithm requires parameters to be manually modified during execution of the program WITHOUT INTERRUPTION of the Table execution process, the parameters can be loaded in Input Storage locations and the *6 Mode can be used to change the values. If values must be in place before program execution commences, use Instruction 91 at the beginning of the program table to prevent execution until a flag is set high (see next section). The initial values can be entered into input locations using the *6 Mode after compiling the table. The flag can then be set high to enable the table(s).

If any program tables *1, *2, *3, or *4 output options are altered and complied in the *0 Mode, values in Input Storage will be set to 0. To preserve values entered in Input Storage, compile with *6.

1.3.2 DISPLAYING AND TOGGLING USER FLAGS

If D is keyed while the CR7 is displaying a location value, the current status of the user flags will be displayed in the following format: "00:01:00:10". The characters represent the flags, the left-most digit represents Flag 1 and right most Flag 8. A "0" indicates the flag is low and a "1" indicates the flag is high. In the above example, Flags 4 and 7 are set high. To toggle a flag, simply key the corresponding number. To return to displaying the input location, press A.

Entering appropriate flag tests into the program allows manual control of program execution. For example: It is desired to be able to manually start the execution of Table 2. Instruction 91 is the first instruction entered in Table 2:

01: P91 If Flag

01: 25 5 is set low 02: 0 Go to end of program table

If Flag 5 is low, all subsequent instructions in Table 2 will be skipped. Flag 5 can be toggled from the *6 Mode, effectively starting and stopping the execution of Table 2.

1.3.3 DISPLAYING AND TOGGLING PORTS

The current status of the Digital Control ports on the active 725 excitation card can be displayed by hitting "0" while looking at an input location (e.g., *6A0). Ports are displayed left to right as C8, C7, ..., C1 (exactly opposite to the flags). A port can be toggled by pressing its number on the keypad while in the port display mode.

The active excitation card defaults to address 1. The active card may only be changed with Instruction 20 in the CR7 Program (Section 9).

1.4 COMPILING AND LOGGING DATA *0 MODE

When the *0 Mode is entered after programming the CR7, the program is compiled (Section 1.1.4) and the display shows "LOG" and the numbers of the program tables that were enabled at compilation. The display is not updated after entering *0.

1-3

SECTION 1. FUNCTIONAL MODES

When the *0, *B, or *D Mode is used to compile, all output ports and flags are set low, the timer (Instruction 26) is reset, and data in Input and Intermediate Storage are RESET TO ZERO.

The CR7 should normally be left in the *0 Mode when logging data. This Mode requires slightly less power than Modes which frequently update the display.

1.5 MEMORY ALLOCATION - *A

1.5.1 INTERNAL MEMORY

There are eight sockets on the CR7 CPU board which are used for Read Only Memory (ROM) or Random Access Memory (RAM). The basic CR7 is provided with 64K of memory: three 8K Programmable Read Only Memory (PROM) chips for a total of 24K ROM and five 8K RAM chips. Appendix E describes how to change RAM and ROM chips.

When powered up, the CR7 displays HELLO while performing a memory check. As the check is performed, a number on the right of the display is incremented as each 8 K block of memory is checked. With standard memory the count will stop at 8. If additional memory card(s) are present, the count will proceed accordingly. The Power-up memory check is quite extensive and can take considerable time if the 709 512K Memory Card is installed. To abort the extensive test (a shorter version is still performed), press the # key. When the memory test is completed, the number of K bytes of RAM plus ROM is displayed.

There are 1744 bytes allotted to program memory. This memory may be used for one program table or shared among all program tables. Tables 3.9-1 to 3.9-4 list the amount of memory used by each program instruction.

Input Storage is used to store the results of Input/Output and Processing Instructions. The values stored in input locations may be displayed using the *6 Mode (Section 1.3).

Intermediate Storage is used by Output Processing Instructions to store the results of intermediate calculations necessary for averages, standard deviations, histograms, etc.

Final Storage holds output data, the results of Output Processing Instructions which are stored when the Output Flag is set high (Section 3.7). The data in Final Storage can be displayed using the *7 Mode (Section 2.3).

Figure OV2-1 illustrates the use of Input, Intermediate, and Final Storage.

Each Input or Intermediate Storage location requires four bytes of memory. Each Final Storage location requires 2 bytes of memory. Low resolution data points require 1 Final Storage location and high resolution data points require 2. Section 2 describes Final Storage and data retrieval in detail.

Table 1.5-1 lists the basic memory areas and the amount of memory allotted to them in the standard CR7.

The size of RAM, including any additional memory cards which may be present, can be determined with the *A Mode (Section 2.4.2)

TABLE 1.5-1. Memory Allocation in Standard CR7

Program System Input Intermediate Final Storage*

PROM Memory Memory Storage* Storage* Storage* Standard w/709

Memory Card Avail. bytes 24K 1744 2160 128 256 36,672 590,960 Avail. Loc.---326418,336280,480

*Default allocation on power-up

1-4

SECTION 1. FUNCTIONAL MODES

TABLE 1.5-2. Description of *A Mode Data

Key Display Entry ID: Data Description of Data

*A 01: XXXX The number of memory locations currently allocated to Input Storage. This

value can be changed by keying in the desired number (minimum of 32, maximum limited by available memory).

A 02: XXXX The number of memory locations currently allocated to Intermediate Storage.

This value can be changed by keying in the desired number (limited by available memory).

A 03: XXXXX The number of memory locations currently allocated to Final Storage. This

number is automatically altered when the number of memory locations in Input and/or Intermediate Storage is changed. A minimum of 768 locations are always retained in Final Storage.

A 04:XXXX The number of bytes remaining in Program memory (1744 bytes total).

Entering 1744 will ERASE ALL MEMORY and put the CR7 through the initial power-up routine.

1.5.2 *A MODE

The *A Mode is used to 1) determine the number of locations allocated to Input, Intermediate, and Final Storage; 2) repartition this memory; 3) check the number of bytes remaining in program memory; 4) erase Final Storage; and 5) to completely reset the datalogger. When *A is keyed, the first value displayed is the number of memory locations allocated to Input Storage. Press A to advance through the memory values. Table 1.5-2 describes what the values seen in the *A Mode represent.

The numbers of memory locations allocated to Input, Intermediate and Final Storage default at power-up to the values in Table 1.5-1.

The sizes of Input and Intermediate Storage may be altered by keying in the desired value and entering it by keying A. The size of Final Storage will be adjusted automatically.

One input or Intermediate Storage location can be exchanged for two Final Storage locations and vice-versa. Input and Intermediate Storage must reside in the CPU board RAM. If additional memory boards are present, it is possible to use all of the CPU board RAM for Input and Intermediate Storage. A minimum 32 Input and 768 Final Storage locations will ALWAYS be retained. If no Intermediate Storage is required, its size may be reduced to

All data in Intermediate and Final Storage are erased when memory is repartitioned. This feature may be used to clear memory without altering programming. The number of locations does not actually need to be changed; the same value can be keyed in and entered. After repartitioning memory, the Tables must be recompiled. Recompiling with *0 erases Input Storage; recompiling with *6 leaves Input Storage unaltered.

If Intermediate Storage size is too small to accommodate the programs or instructions entered, the program will not compile and the "E:04" ERROR CODE will be displayed; the size of Intermediate Storage must be increased before the program will compile. Final Storage size can be maximized by limiting Intermediate Storage size to the minimum number of memory locations necessary to accommodate the programs entered. The number of Final Storage locations and the rate at which data are stored determines how long it will take for Final Storage to fill, at which point new data will write over old.

1.6 MEMORY TESTING AND SYSTEM STATUS - *B

The *B Mode is used to 1) read the signature of the program memory and the software PROMs,

2) display the power-up memory status, 3) display the number of E08 occurrences (Section 3.10), 4) display the number of overrun occurrences (Section 1.1.1), and 5) display PROM version and revision number. Table 1.6-

1-5

SECTION 1. FUNCTIONAL MODES

1 describes what the values seen in the *B Mode represent. The correct signatures of the CR7 PROMs are listed in Appendix B.

A signature is a number which is a function of the data and the sequence of data in memory. It is derived using an algorithm which assures a

99.998% probability that if either the data or its sequence changes, the signature changes. The signature of the program memory is used to determine if the program tables have been altered. During the self check on power-up, the signature computed for a PROM is compared with a signature stored in the PROM to determine if a failure has occurred. The algorithm used to calculate the signature is described in Appendix C.

The contents of windows 8 and 9, PROM version and version revision, are helpful in determining what PROM is in the datalogger. Over the years, several different PROM versions have been released, each with operational differences. When calling Campbell Scientific for datalogger assistance, please have these two numbers available.

TABLE 1.6-1. Description of *B Mode Data

Key Display Entry ID: Data Description of Data

*B 01: XXXXX Program memory

Signature. The value is dependent upon the programming entered and memory allotment. If the Tables have not been previously compiled, they will be compiled and run.

A 02: XXXXX First PROM Signature

A 07: XXXXX No. of overrun

occurrences (Key in 88 to

reset) A 08: X.XXXX PROM version number A 09: XXXX. Version revision number A 01:00 Enter I/O Module No. to

test (usually 1) 1A 01:XXXXX I/O Module 1 RAM

Signature

01:XXXXX I/O Module 1 PROM

Signature

1.7 *C MODE -- SECURITY

The *C Mode is used to secure the user's program information. If security is activated, then the CR7 will block keyboard access to the *1, *2, *3, *4, and *A Modes. Activated security will also block Telecommunications access to the *1, *2, *3, *4, *5, and *D Modes and the Telecommunications C command. A four digit password allows entry to the *C Mode and becomes part of the program memory, affecting the program signature. If security is enabled when *C is keyed, the password must be keyed in before one can advance to window 1. If security is disabled, keying *C brings up window 1 immediately. In window 1 a command can be entered to either enter a new password (1), or temporarily disable security (00) in order to check or alter the programming. The password on power-up is 0000 (unless *D was used to create a custom PROM with the password built in), which disables security. When security is temporarily disabled, it is possible to enter all modes and to alter programming. Keying *0 or *6 will automatically re-enable security, unless the password is 0000.

03: XXXXX Second PROM Signature 04: XXXXX Third PROM Signature

A 05: XXXXX Memory status, No. K

RAM and ROM

A 06: XXXXX No. of E08 occurrences

(Key in 88 to reset)

1-6

Entering the four digit password as an indexed value (i.e. xxxx--, entered by keying C after entering the four digits) blocks access to the *1, *2, *3, *4, and *A Modes, but allows the user to view and change the password.

SECTION 1. FUNCTIONAL MODES

TABLE 1.7-1. *C Mode Entries and Codes

Key Display Entry ID: Data Description

*C 12:0000 Enter current password.

If correct, then advance, else exit *C Mode. 12:00 indicates *C Mode is not in PROMs. If security is disabled, *C advances directly to window 1.

A 01:00 Window 1, enter

command: 00 = disable security and

advance to window 2; subsequent *0 or *6 enables security.

01 = security remains

enabled, but it advances to window 2 and allows entry of a new password.

A 02:XXXX Set new password

(XXXX is current password).

TABLE 1.8-1. *D Mode Commands

Command Description

1 Save ASCII Program 2 Load ASCII Program

71 Save/Load/Clear Program

from Storage Module

A command is entered by keying the command number and A. When Command 1, 2, or 71 is entered, the command number is displayed in the ID field. The user must then key in a baud rate code for command 1 or 2 or the command code for the Storage Module (Table 1.8-2). After the code is keyed in, key A to execute the command. After a command is executed, "13:0000" is displayed; *D must be entered again before another command can be given.

If the CR7 program has not been compiled when a command to save the program is entered, it will be compiled before the command is executed.

TABLE 1.8-2. *D Mode Baud Rate and

Storage Module Codes

A Returns to window 1.

Entering 0000 disables security (window 1 must be set to 0).

1.8 *D MODE -- SAVE OR LOAD PROGRAM

The *D Mode allows the user's program information in the *1, *2, *3, *4, *A, *C (if OSX-

0), and *B Modes to be output to or loaded from printer/computer (ASCII) or SM192/716 Storage Module. Table execution and on-line printer outputs are suspended while in the *D Mode. When *D is keyed, the CR7 will display "13:00".

BAUD RATE STORAGE MODULE CODES COMMAND CODES

0 - 300 baud 1X Save Program X to 1 - 1200 Storage Module 2 - 9600 (X=1-8) 3 - 76,800 2X Load Program X from

Storage Module (X=1-8)

3X Erase Program X from

Storage Module (X=1-8)

1-7

SECTION 1. FUNCTIONAL MODES

All data in Input, Intermediate and Final Storage are erased when a command to load a program is executed or when a program is written to tape.

If nothing is received within 30-40 seconds after giving the command to load a program, the command will be aborted and an error code displayed (E99 for Storage Module or ASCII). Commands 1, 2, and 71 are the only commands that can be executed via telecommunications (Section 5). For commands 1 and 2, the CR7 will use the baud rate already established in telecommunications and will be ready to receive or send the file as soon as the command is received.

TABLE 1.8-3. Progr am Load Error Codes

E 98 Uncorrectable errors detected E 99 Wrong type of file or no data received

1.8.1 TRANSFER TO COMPUTER/PRINTER

This section describes commands 1 and 2 (Table 1.8-1). The PC208 Software automatically uses these commands for uploading and downloading programs.

SENDING ASCII PROGRAM INFORMATION

TABLE 1.8-4. Example Program Listing

From *D Command 1

MODE 1 SCAN RATE 2 1:P17 1:1 1:P0

2:P14 1:1 2:1 3:5 4:1 5:1 6:2 7:1 8:0

3:P92 1:0 2:5 3:10

MODE 1 SCAN RATE 2

4:P71 1:2 2:1

Command 1 is to send the program listing in ASCII. At the end of the listing, the CR7 sends control E (5 hex or decimal) twice. Except when in telecommunications, the baud rate code must be entered after command 1.

Table 1.8-4 is an example of the program listing sent in response to command 1 (the actual listing is in one column but is printed in two columns to save space). Note that the listing uses numbers for each mode: The numbers for *A, *B, and *C modes are 10, 11, and 12, respectively.

5:P0 MODE 2

SCAN RATE 0 MODE 3 MODE 4

1:0 2:0

MODE 10 1:28 2:64 3:19328 4:934

MODE 12 1:0 2:0

MODE 2 SCAN RATE 0

1-8

SECTION 1. FUNCTIONAL MODES

LOAD PROGRAM FROM ASCII FILE Command 2 sets up the CR7 to load a serial

ASCII program. The format is the same as sent in response to command 1 (Table 1.8.4). Except when in telecommunications, the baud rate code must be entered after command 2.

A download file need not follow exactly the same format that is used when listing a program (i.e., some of the characters sent in the listing are not really used when a program is loaded). Some rules which must be followed are:

1. "M" must be the first character other than a

carriage return (CR) or line feed (LF). The "M" serves the same function as "*" does from the keyboard. The order that the Modes are sent in does not matter (i.e., the information for Mode 4 could be sent before that for Mode 1).

2. "S" is necessary prior to the execution

interval (Scan rate ).

3. The colons (:) are used to mark the start of

actual data.

4. A semicolon (;) tells the CR7 to ignore the

rest of the line and can be used after an entry so that a comment can be added.

There are 4 two-character control codes which may be used to verify that the CR7 receives a file correctly:

As a download file is received, the CR7 buffers the data in memory; the data is not loaded into the editor or compiled until the CR7 receives a command to do so. The minimum file that could be sent is the program listing, then ^E^E. ^C^C tells the CR7 to send the signature (Section C.3) for the current buffer of data. If this signature does not match that calculated by the sending device, ^B^B can be sent to discard the current buffer and reset the signature. If the signature is correct, ^D^D can be sent to tell the CR7 to load the buffer into the editor and reset the signature. Once the complete file has been sent and verified, send ^E^E to compile the program and exit the load command.

1.8.2 PROGRAM TRANSFER WITH STORAGE MODULE

The SM192/716 Storage Module must be connected to the CR7. Key *D, then enter command 71. The command to save, load, or clear a program and the program number (Table 1.8-2) is entered. After the operation is finished, "13:0000" is displayed.

The datalogger can be programmed on powerup using a Storage Module. Storage Modules can store up to eight separate programs. If a program is stored as program number 8, and if the Storage Module is connected to the datalogger serial port at power-up, program number 8 is downloaded to the datalogger and compiled.

^B ^B (2hex, 2hex) Discard current buffer

and reset signature

^C ^C (3hex, 3hex) Send signature for

current buffer

^D ^D (4hex, 4hex) Load current buffer and

reset signature

^E ^E (5hex, 5hex) Exit and compile program

1-9

SECTION 1. FUNCTIONAL MODES

This is a blank page.

1-10

SECTION 2. INTERNAL DATA STORAGE

2.1 FINAL STORAGE AREAS, OUTPUT ARRAYS, AND MEMORY POINTERS

Final Storage is that portion of memory where final, processed data are stored. Data must be sent to Final Storage before they can be transferred to a computer or external storage peripheral.

The size of Final Storage is expressed in terms of memory locations or bytes. A low resolution data point (4 decimal characters) occupies one memory location (2 bytes), whereas a high resolution data point (5 decimal characters) requires two memory locations (4 bytes). Table

1.5-1 shows the default allocation of memory locations to Input, Intermediate, and Final Storage. The *A Mode is used to reallocate memory or erase Final Storage (Section 1.5). A minimum of 768 memory locations will ALWAYS be retained in Final Storage.

Final Storage can be represented as ring memory (Figure 2.1-1) on which the newest data are written over the oldest data.

that output array. For example, the ID of 118 in Figure 2.1-2 indicates that the 18th instruction in Table 1 set the Output Flag high.

FIGURE 2.1-2. Output Array ID

2) The output array ID can be set by the user with the second parameter of Instruction 80 (Section 11). The ID can be set to any positive integer up to 511. Instruction 80 must follow the instruction which set the Output Flag high. This option allows the user to make the output array ID independent of the programming. The program can be changed (instructions added or deleted) without changing the output array ID. This avoids confusion during data reduction, especially on long term projects where program changes or updates are likely.

FIGURE 2.1-1. Ring Memory Representation

of Final Data Storage

Output Processing Instructions store data into Final Storage only when the Output Flag is set high. The string of data stored each time the Output Flag is set high is called an output array. The first data point in the output array is a 4 digit Output Array ID. This ID number is set in one of two ways:

1) In the default condition, the ID consists of the program table number and the Instruction Location Number of the instruction which set the Output Flag for

NOTE: If Instruction 80 is used to designate Final Storage and parameter 2 is 0, the output array ID is determined by the position of Instruction 80 or by the position of the instruction setting the Output Flag, whichever occurs last.

Data are stored in Final Storage before being transmitted to an external device. There are four pointers which are used to keep track of data transmission. These pointers are:

1. Data Storage Pointer (DSP)

2. Display Pointer (DPTR)

3. Printer Pointer (PPTR)

4. Telecommunications (Modem) Pointer (MPTR)

2-1

SECTION 2. IN TERNAL DATA STORAGE

The Data Storage Pointer (DSP) is used to determine where to store each new data point in the Final Storage area. The DSP advances to the next available memory location after each new data point is stored.

The DPTR is used to recall data to the LCD display. The positioning of this pointer and data recall are controlled from the keyboard (*7 Mode).

The PPTR is used to control data transmission to a printer, Storage Module, or other serial device. Whenever on-line printer transfer is activated (*4 Mode or Instruction 96), data between the PPTR and DSP are transmitted.

When on-line transfer to a SM192/716 Storage Module is activated by Instruction 96 with output code 30, data is transmitted each time an output array is stored in Final Storage IF THE STORAGE MODULE IS CONNECTED TO THE CR7. If the Storage Module is not connected, the CR7 does not transmit the data nor does it advance the PPTR to the new DSP location. It saves the data until the Storage Module is connected. Then, during the next execution of Instruction 96, the CR7 outputs all of the data between the PPTR and the DSP and updates the PPTR to the DSP location (Section 4.1)

The MPTR is used in transmitting data over a telecommunications interface. When Telecommunications is first entered, the MPTR is set to the same location as the DSP. Positioning of the MPTR is then controlled by commands from the external calling device (Section 5.1).

NOTE: All memory pointers are set to the DSP location when the datalogger compiles a program. For this reason, ALWAYS RETRIEVE UNCOLLECTED DATA BEFORE MAKING PROGRAM CHANGES.

2.2 DATA OUTPUT FORMAT AND RANGE LIMITS

Data are stored internally in Campbell Scientific's Final Storage Format (Appendix C.2). Data may be sent to Final Storage in either LOW RESOLUTION or HIGH RESOLUTION format. Low resolution is the default. To change the resolution, Instruction 78 (Section 11) must precede the Output Instructions in the program table.

2.2.1 RESOLUTION AND RANGE LIMITS

Low resolution data is a 2 byte format with 3 or 4 significant digits and a maximum magnitude of ±6999. High resolution is a 4 byte format with 5 significant digits and a maximum possible output value of ±99999 (see Table 2.2-1 below).

TABLE 2.2-1. Resolution Range Limits of

CR7 Data

Minimum Maximum

Resolution Zero Magnitude M agnitude

Low 0.000 ±0.001 ±6999. High 0.0000 ±.00001 ±99999.

The resolution of the low resolution format is reduced to 3 significant digits when the first (left most) digit is 7 or greater (Table 2.2-2). Thus, it may be necessary to use high resolution output or an offset to maintain the desired resolution of a measurement. For example, if water level is to be measured and output to the nearest 0.01 foot, the level must be less than 70 feet for low resolution output to display the 0.01 foot increment. If the water level is expected to range from 50 to 80 feet the data could either be output in high resolution or could be offset by 20 feet (transforming the range to 30 to 60 feet).

2-2

SECTION 2. IN TERNAL DATA STORAGE

TABLE 2.2-2. Decimal Location in Low

Resolution Format

Absolute Value Decimal Location

0 - 6.999 X.XXX 7 - 69.99 XX.XX

70 - 699.9 XXX.X

700 - 6999. XXXX.

While output data have the limits described above, the computations performed in the CR7 are done in floating point arithmetic. Values are rounded when converting to Final Storage Format.

2.2.2 INPUT AND INTERMEDIATE STORAGE DATA FORMAT

In Input and Intermediate Storage, numbers are stored and processed in a binary format with a 23 bit binary mantissa and a 6 bit binary exponent. The largest and smallest numbers that can be stored and processed are 9 x 10 and 1 x 10 number determines the resolution of the arithmetic. A rough approximation of the resolution is that it is better than 1 in the seventh digit. For example, the resolution of 97,386,924 is better than 10. The resolution of

0.0086731924 is better than 0.000000001. A precise calculation of the resolution of a

number may be determined by representing the number as a mantissa between .5 and 1 multiplied by 2 raised to some integer power. The resolution is the product of that power of 2 and 2 .9336 * 29, the resolution is 29 * 2

0.0000305. A description of Campbell Scientific's floating point format may be found in the description of the J and K telecommunications commands in Appendix C.

-19

, respectively. The size of the

-24

. For example, representing 478 as

-24

= 2

-15

2.3 DISPLAYING STORED DATA ON KEYBOARD/DISPLAY - *7 MODE

The *7 Mode is used to display Final Storage data. Enter the Mode by keying *7. The display will show "07:XXXXX", whe re XXXXX is the Final Storage location (DSP) where the next data will be stored. Two options are available:

1. Press A to advance and display the output array ID of the oldest array in Final Storage.

2. Enter a Final Storage location number. When A is pressed, the DPTR will jump to the location entered and, if it is not at the start of an array, advance to the first start of array. The display will show the Array ID.

Repeated use of the A key advances through the output array, while use of the B key backs the DPTR through memory.

The Final Storage location of the data point being viewed may be displayed by keyi ng #. At this point, another location may be entered followed by A to jump to the start of the output array equal to or just ahead of the location entered. Whenever a location number is displayed by keying #, the corresponding data point can be displayed by keying C. To advance to the start of the next output array, key #A. To back up one output array, key #B.

TABLE 2.3-1. *7 Mode Command Summary

Key Action

A Advance to next data point B Back-up to previous data point # Display location number of currently

displayed data point value

C Display value of current location #A Advance to start of next output array #B Back-up to previous output array

2-3

SECTION 2. IN TERNAL DATA STORAGE

This is a blank page.

2-4

SECTION 3. INSTRUCTION SET BASICS

The instructions used to program the CR7 are divided into four types: Input/Output (I/O), Processing, Output Processing, and Program Control. I/O Instructions are used to make measurements and store the readings in input locations or to initiate analog or digital port output. Processing Instructions perform numerical operations using data from Input Storage locations and place the results back into specified Input Storage locations. Output Processing Instructions provide a method for generating time or event dependent data summaries from processed sensor readings residing in specified Input Storage locations. Program Control Instructions are used to direct program execution based on time and/or conditional tests on input data and to direct output to external devices.

Instructions are identified by a number. Each instruction has a number of parameters which give the CR7 the information it needs to execute the instruction.

The set of instructions available in the CR7 is determined by the Programmable Read Only Memory chips (PROMS) that are installed. Appendix B lists the software options available.

3.1 PARAMETER DATA TYPES

There are three different data types used for Instruction parameters: Floating Point (FP), 4 digit integers (4), and 2 digit integers (2). In the listings of the instruction parameters (Sections 9-12), the parameter data type is identified by its abbreviation. Different data types are used to allow the CR7 to make the most efficient use of its memory.

Floating Point parameters are used to enter numeric constants for calibrations or arithmetic operations. While it is only possible to enter five digits (magnitude ±.00001 to ±99999.), the internal format has a much greater range

-19

(1x10

to 9x1018, Section 2.2.1).

3.2 REPETITIONS/CARD NUMBER

The repetitions parameter on many of the I/O, Processing, and Output Processing Instructions is used to repeat the instruction on a number of sequential Input Channels or Input Storage locations. Separate parameters are used to specify the card and input channel on which to make the first measurement. For example, if you have four differential voltage measurements to make on the same voltage range, wire the inputs to sequential channels and instead of entering the Differential Voltage Measurement Instruction 4 times, enter it once with four repetitions. The instruction will make four measurements starting on the specified channel number and continuing through the three succeeding differential channels, with the results being stored in the specified input location and the three succeeding input

locations. Averages for all four measurements can be calculated by entering the Average Instruction with four repetitions.

The CR7 will automatically continue repetitions from the last channel of one card to the first channel of the next sequentially numbered 723(-T) Analog Input Card or 725 Pulse Counter Card. Measurements on the 726 50 volt Analog Input Card will not advance correctly from one card to the next; enter separate measurement instructions for each card.

When several of the same type of measurements are to be made but the calibrations of the sensors are different, it requires less time to use a single measurement instruction with repetitions and then apply the calibrations with Instruction 53 than it does to enter the instruction several times in order to use different multipliers and offsets. This is due to the set up and calibration time for each measurement instruction. However, if time is not a constraint, separate instructions may make the program easier to follow.

3.3 ENTERING NEGATIVE NUMBERS

After keying in a number, press C or "-" to change the number's sign. On floating point numbers, a minus sign (-) will appear to the left of the number.

Excitation voltages in millivolts for I/O Instructions are 4 digit integers; when C is pressed, minus signs (-) will appear to the right of the number indicating a negative excitation.

3-1

SECTION 3. INSTRUCTION SET BASICS

Even though this display is the same as that indicating an indexed input location, (Section

3.4) there is no indexing effect on excitation voltage.

3.4 INDEXING INPUT LOCATIONS

When used within a Loop, the parameters for input locations can be Indexed to the loop counter. The loop counter is added to the indexed value to determine the actual input location the instruction acts on. Normally, the loop counter is incremented by one after each pass through the loop. Instruction 90, Step Loop Index, allows the increment step to be changed. See Instructions 87 and 90, Section 12, for more details.

To index an input location (4 digit integer), key C after keying the value but before entering the parameter. Two minus signs (-) will be displayed to the right of the parameter.

3.5 VOLTAGE RANGE AND OVERRANGE DETECTION

The RANGE code parameter on Input/Output Instructions is used to specify the full scale voltage range of the measurement and the integration period for the measurement (Table

3.5-1).

Select the smallest full scale range that is greater than or equal to the full scale output of the sensor being measured. Using the smallest possible range will result in the best resolution for the measurement.

Two different integration sequences are possible. The slow integration, 16.67 milliseconds, is one 60 Hz cycle and rejects noise from 60 Hz AC line power as well as having better rejection of random noise than the fast integration. A PROM with 50Hz rejection is available for countries whose electric utilities operate at 50 Hz (Appendix B).

When a voltage input exceeds the range programmed, the value stored is the maximum negative number, displayed in the *6 Mode as

-99999. In output data from Final Storage, this becomes -6999 in low resolution or -99999. in high resolution.

An input voltage greater than +8 volts on one of the analog inputs will result in errors and possible overranging on the other analog inputs. Voltages greater than 16 volts may permanently damage the CR7.

TABLE 3.5-1. Input Voltage Ranges and Codes

Range Code Full Scale Range Resolution*

Slow Fast

16.67ms 250µs Integ. Integ.

1 11 ±1500 microvolts 50 nanovolts 2 12 ±5000 microvolts 166 nanovolts 3 13 ±15 millivolts 500 nanovolts 4 14 ±50 millivolts 1.66 microvolts 5 15 ±150 millivolts 5 microvolts 6 16 ±500 millivolts 16.6 microvolts 7 17 ±1500 millivolts 50 microvolts 8 18 ±5000 millivolts 166 microvolts

*Differential measurement, resolution for single-ended measurement is twice value shown.

3.6 OUTPUT PROCESSING

Most Output Processing Instructions require both an intermediate processing operation and a final processing operation. For example, when the Average Instruction, 71, is executed,

the intermediate processing operation increments a sample count and adds each new Input Storage value to a cumulative total residing in Intermediate Storage. When the Output Flag is set, the final processing operation divides the total by the number of

3-2

SECTION 3. INSTRUCTION SET BASICS

sample counts, stores the resulting average in Final Storage and zeros the value in Intermediate Storage so that the process starts over with the next execution.

Final Storage is the default destination of data output by Output Processing Instructions (Sections OV2, 1.5, 2.1). Instruction 80 may be used to direct output to Input Storage or to Final Storage.

Output Processing Instructions requiring intermediate processing sample the specified input location(s) each time the Output Instruction is executed, NOT necessarily each time the location value is updated by an I/O Instruction. For example: Suppose a temperature measurement is initiated by Table 1 which has an execution interval of one second. The instructions to output the average temperature every 10 minutes are in Table 2 which has an execution interval of 10 seconds. The temperature will be measured 600 times in the 10 minute period, but the average will be the result of only 60 of those measurements because the instruction to average is executed only one tenth as often as the instruction to make the measurement.

Final processing occurs only when the Output Flag is set (Section 3.7.1). The Output Flag, Flag 0, is set at desired intervals or in response to specified conditions by using an appropriate Program Control Instruction (Section 11).

3.7 USE OF FLAGS: OUTPUT AND PROGRAM CONTROL

There are 10 flags which may be used in CR7 programs. Two of the flags have functions with Output Processing Instructions: Flag 0 controls final processing and data storage, and Flag 9 can disable intermediate processing. Flags 1-8 may be used as desired in programming the CR7. Flags 0 and 9 are automatically set low at the beginning of the program table. Flags 1-8 remain unchanged until acted on by a Program Control Instruction or until manually toggled from the *6 Mode.

TABLE 3.7-1. Flag Description

Flag 0 - Output Flag Flag 1 to 8 - User Flags Flag 9 - Intermediate Processing Disable

Flag

Flags are set with Program Control Instructions. The Output Flag, Flag 0, and the intermediate processing disable flag, Flag 9, will always be set low if the set high condition is not met. The status of flags 1-8 are not changed if a conditional test is false.

3.7.1 THE OUTPUT FLAG

A set of processed data values is placed in Final Storage by Output Processing Instructions when the Output Flag, Flag 0, is set high. This set of data is called an output array. The Output Flag is set according to time or event dependent intervals using Program Control Instructions specified by the user. The Output Flag is set low at the beginning of each table.

Each group of Output Processing Instructions creating an output array must be preceded by a Program Control Instruction that sets the Output Flag.

Output is most often desired at fixed intervals; this is accomplished with Instruction 92, If Time, which checks the clock to see if it is X minutes into a Y minute interval. If the time condition is met, a command is executed. Output at the beginning of the interval by making Parameter 1, time into the interval, 0. Parameter 2, the time interval in minutes, is how often output will occur; i.e., the Output Interval. Enter 10 for parameter 3, the command code, to set Flag 0 high. Instruction 92 is followed in the program table by the Output Instructions which define the output array desired.

The time interval is synchronized to 24 hour time; output will occur on each integer multiple of the Output Interval starting from midnight (0 minutes). If the Output Interval is not an even divisor of 1440 minutes (24 hours), the last output interval of the day will be less than the specified time interval. Output will occur at midnight and will resume synchronized to the new day.

3-3

SECTION 3. INSTRUCTION SET BASICS

NOTE: If the Output Flag is already set

high and the test condition of a subsequent Program Control Instruction acting on the flag fails, the flag is set low. This feature eliminates having to enter another instruction to specifically reset the Output Flag at the end of an output array before proceeding to another group of Output Instructions with a different output interval (see example in OV4.3).

3.7.2 THE INTERMEDIATE PROCESSING DISABLE FLAG

The Intermediate Processing Disable Flag, Flag 9, suspends intermediate processing when it is set high. This flag is used to restrict sampling for averages, totals, maxima, minima, etc., to times when certain criteria are met. The flag is automatically set low at the beginning of the program table.

As an example, suppose it is desired to obtain a wind speed rose incorporating only wind speeds greater than or equal to 4.5 m/s. The wind speed rose is computed using the Histogram Instruction 75, and wind speed is stored in Input location 14, in m/s. Instruction 89 is placed just before Instruction 75 and is used to set Flag 9 high if the wind speed is less than 4.5 m/s:

NOTE: Flag 9 is automatically reset the same as Flag 0. If the intermediate processing disable flag is already set high and the test condition of a subsequent Program Control Instruction acting on Flag 9 fails, the flag is set low. This feature eliminates having to enter another instruction to specifically reset Flag 9 before proceeding to another group of test conditions.

3.7.3 USER FLAGS

Flags 1-8 are not dedicated to a specific purpose and are available to the user for general programming needs. The user flags can be manually toggled from the keyboard in the *6 Mode (Section 1.3) or from a computer using TERM's monitor feature. By inserting flag tests (Instruction 91) at appropriate points in the program, the user can manually set flags to direct program execution.

3.8 PROGRAM CONTROL LOGICAL CONSTRUCTIONS

Most of the Program Control Instructions have a command code parameter which is used to specify the action to be taken if the condition tested in the instruction is true. Table 3.8-1 lists these codes.

TABLE 3.7-2. Example of the Use of Flag 9

Inst. Param. Loc. No. Entry Description

X P 89 If wind speed < 4.5 m/s

1 14 Wind speed location 2 4 Comparison: < 3 4.5 Minimum wind speed for

histogram

4 19 Set Flag 9 high X+1 P 75 Histogram X+2 P 86 Do

1 29 Set Flag 9 Low

TABLE 3.8-1. Command Codes

0 - Go to end of program table

1-9, 79-99 - Call Subroutine 1-9, 79-99

10-19 - Set Flag 0-9 high 20-29 - Set Flag 0-9 low

30 - Then Do 31 - Exit loop if true

32 - Exit loop if false 41-48 - Set port 1 - 8 high* 51-58 - Set port 1 - 8 low* 61-68 - Toggle port 1 - 8* 71-78 - Pulse port 1 - 8* 100 ms

* Port commands default to Excitation Card 1; Instruction 20 is used to change to another card.

3.8.1 IF THEN/ELSE COMPARISONS

When Command 30, THEN DO, is used with one of the IF Instructions, 88-92, the instruction is followed immediately by instructions to

3-4

SECTION 3. INSTRUCTION SET BASICS

execute if the comparison is true. The Else Instruction, 94, is optional and is followed by the instructions to execute if the comparison is false. The End Instruction, 95, marks the end of the branching started by the IF Instruction. Subsequent instructions are executed regardless of the outcome of the comparison (Figure 3.8-1).

FIGURE 3.8-1. If Then/Else Execution

Sequence

If Then/Else comparisons may be nested to form logical AND or OR branching. Figure 3.82 illustrates an AND construction. If conditions A and B are true, the instructions included between IF B and the first End Instruction will be executed. If either of the conditions is false, execution will jump to the corresponding End Instruction, skipping the instructions between.

Call subroutine X (86, command=X) END B (95) END A (95)

FIGURE 3.8-3. Logical OR Construction

A logical OR can also be constructed by setting a flag if a comparison is true. (The flag is cleared before making the comparisons.) After all comparisons have been made, execute the desired instructions if the flag is set.

The Begin Case Instruction 93 and If Case Instruction 83 allow a series of tests on the value in an input location. The case test is started with Instruction 93 which specifies the location to test. A series of Instructions 83 are then used to compare the value in the location with fixed values. When the value in the input location is less than the fixed value specified in Instruction 83 the command in that Instruction 83 is executed; when the next Instruction 83 is encountered, execution branches to the END Instruction 95 which closes the case test (see Instruction 93).

3.8.2 END, INSTRUCTION 95

END, Instruction 95, is required to mark the end of:

1. A Subroutine (starts with Instruction 85)

2. A Loop (starts with Instruction 87)

3. An IF ... THEN DO sequence (starts with one of Instructions 89-93 with the THEN DO command 30).

4. A case statement (starts with Instruction 93)

FIGURE 3.8-2. Logical AND Construction

Figure 3.8-3 illustrates the instruction sequence that will result in subroutine X being executed if either A or B is true.

IF A (88-92 with command 30) Call subroutine X (86, command=X) ELSE (94) IF B (88-92 with command 30)

The IF instructions 89-93 require Instruction 95 only when the THEN DO command 30 is used.

If one of the above instructions is used without the corresponding END, the CR7 will display error 22 when compiling the program. Error 21 is displayed if END is used without being preceded by one of these instructions (Section

3.10).

An END instruction is always paired with the most recent instruction that requires an END and does not already have one. A way of visualizing this is to draw lines between each instruction requiring an END and the END paired with it (as in Figure 3.8-2). The lines must not cross. To debug logic or find a missing or extra END error, list the program and draw the lines.

3-5

SECTION 3. INSTRUCTION SET BASICS

Subroutines can be called from other subroutines; they cannot be embedded within other subroutines. A subroutine must end before another subroutine begins (Error 20). Any loops or IF...THEN DO sequences started within a subroutine must end before the subroutine.

3.8.3 NESTING

A branching or loop instruction which occurs before a previous branch or loop has been closed with the END instruction is nested. The maximum nesting level is 9 deep. Error 30 is displayed when attempting to compile a program which is nested too deep.

The Loop Instruction, 87, counts as 1 level. Instructions 86, 88, 89, 91, and 92 each count as one level when used with the THEN DO command 30. Use of Else, Instruction 94, also counts as one nesting level each time it is used. For example, the AND construction above is nested 2 deep while the OR construction is nested 3 deep. Branching and loop nesting

starts at zero within each subroutine and then returns to the previous level after returning from the subroutine.

Subroutine calls do not count as nesting with the above instructions. They have a separate nesting limit of seven (Instruction 85, Section 12).

Any number of groups of nested instructions may be used in any of the three Programming Tables. The number of groups is only restricted by the program memory available.

3.9 INSTRUCTION MEMORY AND EXECUTION TIME

The standard CR7 has 1744 bytes of program memory available for the programs entered in the *1, *2, and *3 program tables. Each instruction also makes use of varying numbers of Input, Intermediate, and Final Storage locations. The following tables list the memory used by each instruction and the approximate time required to execute the instruction.

TABLE 3.9-1. Input/Output Instruction Memory

R = No. of Reps. D = Delay

INSTRUCTION MEMORY EXECUTION TIME (ms)

INPUT PROG. Slow or No Fast LOC. BYTES Integration Integration

1 VOLT (SE) R 15 57.4 + 22R 16 + 2.9R 2 VOLT (DIFF) R 15 54 + 43.4R 19 + 4.7R 3PULSE R 15 4 + 2R 4 EX-DEL-SE R 20 56.8 + (22.6 + D)R 23.4 + (3.3 + D)R 5 AC HALF BR R 18 57.7 + 44R 21.1 + 5.5R 6 FULL BR R 18 58 + 87.3R 24.2 + 9.6R 7 3W HALF BR R 18 58.8 + 88.7R 24.3 + 11.7R

9 FULL BR-MEX R 19 104 + 175R 31.5 + 20.4R 10 BATT. VOLT 1 4 22.6 11 TEMP (107) R 15 23 + 5.4R 12 RH (207) R 17 23.3 + 5.4R 13 TEMP-TC SE R 18 59.8 + 21.9R 25.2 + 6.1R 14 TEMP-TC DIF R 18 61 + 43.2R 21.5 + 7.85R 16 TEMP-RTD R 15 0.4 + 2.7R 17 TEMP-INTERNL 1 4 116.2 18 TIME 1 7 1.4 19 SIGNATURE 1 4 607.2 20 PORT SET 1 4 2.9 21 ANALOG OUT 1 5 3.6 22 EXCIT-DEL 1 11 10.8 + D 23 SELECT I/O MODULE 0.4 26 TIMER 1 or 0 4 0.54 to reset, 0.25 to load into location

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SECTION 3. INSTRUCTION SET BASICS

TABLE 3.9-2. Processing Instruction Memory and Execution Times

R = No. of Reps.

MEMORY

INPUT INTER. PROG.

INSTRUCTION LOC. LOC. BYTES EXECUTION TIME (ms)

30 Z=F 1 0 8 0.3 31 Z=X 1 0 6 0.5 32 Z=Z+1 1 0 4 0.6 33 Z=X+Y 1 0 8 1.1 34 Z=X+F 1 0 10 0.9 35 Z=X-Y 1 0 8 1.1 36 Z=X*Y 1 0 8 1.2 37 Z=X*F 1 0 10 0.9 38 Z=X/Y 1 0 8 2.7 39 Z=SQRT(X) 1 0 6 12.0 40 Z=LN(X) 1 0 6 7.4 41 Z=EXP(X) 1 0 6 5.9 42 Z=1/X 1 0 6 2.6 43 Z=ABS(X) 1 0 6 0.7 44 Z=FRAC(X) 1 0 6 0.3 45 Z=INT(X) 1 0 6 1.0 46 Z=X MOD F 1 0 10 3.2 47 Z=XY 1 0 8 13.3 48 Z=SIN(X) 1 0 6 6.5 49 SPA MAX 1 or 2 0 7 1.5 + 0.9 (swath-1) 50 SPA MIN 1 or 2 0 7 1.7 + 0.9 (swath-1) 51 SPA AVG 1 0 7 3.3 + 0.6 (swath-1) 53 A*X+B 4 0 36 2.5 + 0.4 scaling pair 54 BLOCK MOVE R 0 10 0.18 + 0.17R 55 POLYNOMIAL R 0 31 1.2 + R(2.0 + 0.4 * order) 56 SAT VP 1 0 6 4.2 57 WDT-VP 1 0 10 8.1 58 LP FILTER R R + 1 13 0.5 + 2.2R 59 X/(1-X) 1 0 9 0.4 + 3.0R 61 INDIR MOVE 1 0 6 0.35 neither indexed

0.54 one location indexed

0.73 both locations indexed

66 ARC TAN 1 0 8 6.7

3-7

SECTION 3. INSTRUCTION SET BASICS

TABLE 3.9-3. Output Instruction Memory and Execution Times

R = No. of Reps.

INSTRUCTION MEMORY EXECUTION TIME (ms)

INTER. FINAL PROG. FLAG 0 LOW FLAG 0 HIGH LOC. VALUES

69 WIND VECTOR 2+9R (2, 3, or 4)R 12

Options 00, 01, 02 3.5 + 17.5R 3.5 + 75R Options 10, 11, 12 3.5 + 16R 3.5 + 30R

70 SAMPLE 0 R 5 0.1 0.4+ 0.6R 71 AVERAGE 1+R R 7 0.9+ 0.5R 2.1+ 3.0R 72 TOTALIZE R R 7 0.6+ 0.5R 1.1+ 1.0R 73 MAXIMIZE (1 or 2)R (1,2,or3)R 8 0.9+ 1.7R 1.3+ 2.8R 74 MINIMIZE (1 or 2)R (1,2,or3)R 8 0.9+ 1.7R 1.3+ 2.8R 75 HISTOGRAM 1+bins*R bins*R 24 0.4+ 3.1R 0.9+

77 REAL TIME 0 1 to 4 4 0.1 1.0 78 RESOLUTION 0 0 3 0.4 0.4 79 SMPL ON MM R R 7 0.3 1.1 80 STORE AREA 0 0 5 82 STD. DEV. 1+3R R 7

BYTES

R(3.3+2.8*bins)

Output values may be sent to either Final Storage or Input Storage with Instruction 80.

TABLE 3.9-4. Program Control Instruction Memory and Execution Times

INSTRUCTION MEMORY EXECUTION TIME (ms)

INTER. PROG. LOC. BYTES

83 IF CASE <F 0 9 0.5 85 LABEL SUBR 0 3 0.0 86 DO 0 5 0.1 87 LOOP 1 9 0.2 88 IF X<=>Y 0 10 0.6 89 IF X<=>F 0 12 0.4 90 LOOP INDEX 0 3 0.5 91 IF FLAG 0 6 0.2 92 IF TIME 1 11 0.3 93 BEGIN CASE 1 8 0.2 94 ELSE 0 4 0.2 95 END 0 4 0.2 96 SERIAL OUT 0 3 98 SEND CHAR. 0 4

3-8

SECTION 3. INSTRUCTION SET BASICS

3.10 ERROR CODES

There are four types of errors flagged by the CR7: Compile, Run Time, Editor, and *D Mode. When an error is detected, an E is displayed followed by the 2 digit error code.

Compile errors are errors in programming which are detected once the program is keyed in and compiled for the first time (*0, *6, or *B Mode entered).

Run Time errors are detected while the program is running. Error 31 is the result of a programming error. Error 8 is the result of a hardware and software "watchdog" that checks the processor state, software timers, and program related counters. The watchdog will attempt to reset the processor and program execution if it finds that the processor has bombed or is neglecting standard system

updates, or if the counters are out of allowable limits. Error code 08 is flagged when the watchdog performs this reset.

Error 8 is occasionally caused by voltage surges or transients. Frequent repetitions of E08 are indicative of a hardware problem or a software bug and should be reported to Campbell Scientific. The CR7 keeps track of the number of times (up to 99) that E08 has occurred. The number can be displayed and reset with the Telecommunications A command (Section 5.1).

Editor errors are detected as soon as an incorrect value is entered and are displayed immediately.

*D Mode errors indicate problems with saving or loading a program. Only the error code is displayed.

TABLE 3.10-1. Error Codes

Code Type Description

01 Run Time I/O Module does not respond 03 Editor Program table full 04 Compile Intermediate Storage full 08 Run Time CR7 reset by watchdog timer 09 Run Time Data sent to unallocated Input Storage 11 Editor Attempt to allocate more Input or Intermediate Storage than is available 20 Compile SUBROUTINE encountered before END of previous subroutine 21 Compile END without IF, LOOP or SUBROUTINE 22 Compile Missing END, nonexistent SUBROUTINE 24 Compile ELSE in SUBROUTINE without IF 25 Compile ELSE wi thout IF 26 Compile EXIT LOOP without LOOP 30 Compile IF and/or LOOP nested too deep 31 Run Time SUBROUTINES nested too deep 40 Compile Table 2 Execution interval too short 40 Editor Instruction not in PROM 60 Compile Inadequate Input Storage for FFT 61 Compile Burst Mode Scan Rate too short 97 *D MODE Tape data not received within 30 seconds 98 *D MODE Uncorrectable errors detected 99 *D MODE Wrong file type, editor error or program not received

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SECTION 3. INSTRUCTION SET BASICS

This is a blank page.

3-10

SECTION 4. EXTERNAL STORAGE PERIPHERALS

External data storage devices are used to provide a data transfer medium that the user can carry from the test site to the lab and to supplement the internal storage capacity of the CR7, allowing longer periods between visits to the site. The standard data storage peripherals for the CR7 are the Storage Modules (Section 4.4). Output to a printer or related device is also possible (Section 4.5). These peripherals are connected to the CR7 through the 9 pin serial connector.

Data output to a peripheral device can take place ON-LINE (automatically, as part of the CR7's routine operation) or it can be MANUALLY INITIATED. On-line data transfer is accomplished with Instruction 96 or with the *4 Mode (Section 4.1). Manual initiation is done in the *8 or *9 Modes (Section 4.2). Regardless of the method, the source of any data transferred is Final Storage.

A modem is another type of peripheral that can be connected to the CR7. Communication via a modem (Telecommunications) is discussed in Section 5.

The CR7 can output data to multiple peripherals (i.e., a modem and Storage Module could be connected at the same time). However, only one modem may be connected to the CR7 at any one time. It is possible to connect two Storage Modules, although it is seldom necessary.

The CR7 can tell whether or not a SM192 or SM716 Storage Module is present. When Instruction 96 or *9 is used to send data to one of these Storage Modules, the CR7 will not send data if the Storage Module is not connected (Section 4.4.2).

4.1 ON-LINE DATA TRANSFER INSTRUCTION 96, *4 MODE

On-line data transfer is accomplished with Instruction 96 entered in the datalogger program. The *4 Mode is retained from earlier software to maintain compatibility with existing programs. Use only one method to enable output. If using Instruction 96, do not enable output in the *4 Mode.

4.1.1 INSTRUCTION 96

Instruction 96 enables output to external storage peripherals under program control. This instruction must be included in the datalogger program for on-line data transfer to take place. Instruction 96 needs to be included only once in the program tables and should follow the Output Processing Instructions. The suggested programming sequence is:

1. Set the Output Flag.

2. If you wish to set the output array ID, enter

Instruction 80 (Section 11).

3. Enter the appropriate Output Processing

Instructions.

4. Enter Instruction 96 to enable the on-line transfer of Final Storage data to the specified device. If outputting to both tape and a Storage Module or printer option, Instruction 96 must be entered twice.

Instruction 96 has a single parameter which specifies the peripheral to enable. Table 4.1-1 lists the output device codes.

TABLE 4.1-1. Output Device Codes for

Instruction 96

CODE DEVICE

1x Printer, Printable ASCII 2x Printer, Binary 30 SM192/716 Storage Module 31 Send filemark to SM192/716

x = BAUD RATE CODE

0 300 1 1200 2 9600 3 76,800

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SECTION 4. EXTERNAL STORAGE PERIPHERALS

Only one of the options 1x, 2x, or 30 may be used in a program. If using a SM64 Storage

Module, output code 21 should be used. Use of the SM192/716 is discussed further in Section

4.4, print output formats are discussed in Section 4.5.

4.1.2 *4 MODE

The *4 Mode may be used in place of Instruction 96 to enable or disable printer output and to set the printer baud rate. The first parameter is a two digit number determining the printer status. The second is the baud rate code. To enter a different status, key in the appropriate code from Table 4.1-2, followed by "A". Printer data is sent in the printable ASCII format only (Section 4.5). If printer status is changed during execution of the program tables, execution stops until the programs are recompiled. Instruction 96 should be used to send data to the SM192/716 Storage Modules. Do not use *4 if Instruction 96 is used in the program.

TABLE 4.1-2. *4 Mode Parame ters and Codes

Keyboard Display Entry ID: Data Description of Data

*4 04:00 A 01:XX Output Enable Code A 02:XX Baud Rate Code

Output Enable Codes

Code Description 00 printer disabled 01 printer enabled, ASCII

Baud Rate Codes

4.2 MANUALLY INITIATED DATA OUTPUT - *9 MODE

Data may be transferred to tape using the *8 Mode and to printer or Storage Module using the *9 Mode. These Modes allow the user to retrieve a specific block of data, on demand, regardless of whether or not the CR7 is programmed for on-line data output.

If external storage peripherals are not left online, the maximum allowable time between visiting the site to retrieve data must be calculated to insure that data placed in Final Storage are not written over before they are collected. In order to make this calculation, users must determine: (1) the size of Final Storage, (2) the number of output arrays being generated, (3) the number of low and/or high resolution data points included in each output array, and (4) the rate at which output arrays are stored in Final Storage. When calculating the number of data points per output array, remember to add 1 overhead data point (2 bytes) per array for the output array ID.

For example, assume that 19,296 locations are assigned to Final Storage (*A Mode), and that 1 output array, containing the Array ID (1 memory location), 9 low resolution data points (9 memory locations) and 5 high resolution data points (10 memory locations) is stored each hour. In addition, an output array with the Array ID and 5 high resolution data points (11 memory locations) is stored daily. This is a total of 491 memory locations per day ((20 x 24) + 11). 19,296 divided by 491 = 39.3 days. Therefore, the CR7 would have to be visited every 39 days to retrieve data, because write-over would begin in the 40th day.

Code Baud Rate 00 300

01 1200 02 9600 03 76,800

4-2

4.2.1 MANUAL STORAGE MODULE OR PRINTER DUMP - *9 MODE

Using the *9 Mode, data in Final Storage can be transmitted as ASCII or binary data out the serial port by manually initiating a dump. If online printing is enabled with Instruction 96 or the *4 Mode, entering *9 will stop it. On-line printing will be re-enabled if no keyboard entries are made for 3.4 minutes. Return to the *0 Mode when the dump is completed.

When on-line Storage Module or printer transfer is not enabled and the *9 Mode is used to dump new data, the start of dump pointer (PPTR) will remain where it was when the dump was completed or

SECTION 4. EXTERNAL STORAGE PERIPHERALS

aborted until the next time the *9 Mode is entered. If the End of Dump location (window 2) is changed while in the *9 Mode, the TPTR will be set to its previous value when the *9 Mode is exited. Changing the program and compiling moves the PPTR to the current DSP location.

NOTE: A printer dump is aborted by keying #.

TABLE 4.2-2. *9 Mode Entries

Display

Key ID:DATA Description

*9 09:00 Output Code

1X Printable ASCII 2X Final Storage Format 30 SM192/716 Storage

Module

31 Send File Mark to

SM192/716 than send data

x = Baud Rate Code

0 300 1 1200 2 9600 3 76800

A 01:XXXXX Start of Dump location,

initially the PPTR location, a different location may be keyed in if desired. To dump all data in Final Storage, enter into window #1 a number 1 greater than the End of Dump location.

A 02:XXXXX End of Dump location,

initially the DSP location, a different location may be keyed in if desired.

A 03:00 Ready to Dump, to

initiate dump, key any number then A. While dumping, "09:" will be displayed in the ID field and the location number in the Data field. The location number will stop incrementing when the dump is complete.

4.3 STORAGE MODULE

The Storage Module stores data in battery backed RAM. Backup is provided by an internal lithium battery. The RAM is internal on the SM192/716 and on a PCMCIA card on the CSM1. Operating power is supplied by the CR7 over pin 1 of the CS I/O connector. When power is applied to the Storage Module, a File Mark is placed in the data (if a File Mark is not the last data point already in storage).

The File Mark separates data. For example, if you retrieve data from one CR7, disconnect the Storage Module and connect it to a second CR7; a File Mark is placed in the data. This mark follows the data from the first CR7, but precedes the data from the second.

The SM192 has 192K bytes of RAM storage; the SM716 has 716K bytes. Both can be configured as either ring or fill and stop memory. The size of memory in the CSM1 depends on the PC card used. The CSM1 is always fill and stop.

4.3.1 USE OF TWO STORAGE MODULES

It is possible to connect two Storage Modules to the CR7 for on-line storage. One module must be configured as fill and stop and the other as ring memory (see Storage Module operator's manual for configuring information). Data is written to both modules simultaneously. The module configured as fill and stop quits accepting data once it is full while that with the ring memory continues to store new data over old. The Storage Modules must be retrieved before the module configured as ring memory wraps around memory a second time.

4.3.2 STORAGE MODULE USE WITH INSTRUCTION 96

When output to the Storage Module is enabled with Instruction 96, the Storage Module(s) may be either left with the CR7 for on-line data transfer and periodically exchanged, or brought to the site for data transfer.

USE OF STORAGE MODULE TO PICK UP DATA

The CR7 can tell when the Storage Module is connected. Each time Instruction 96 is executed and there is data to output, the CR7 checks for the presence of the Storage Module.

4-3

SECTION 4. EXTERNAL STORAGE PERIPHERALS

If a Storage Module is not connected no data are sent and the Printer Pointer (PPTR, Section

2.1) is not advanced. When a Storage Module is connected, two

things happen:

1. Immediately upon connection, a File Mark is placed in the Storage Module Memory following the last data stored.

2. During the next execution of Instruction 96, the CR7 detects the Storage Module and outputs all data between the PPTR and the DSP location.

The File Mark allows the operator to distinguish blocks of data from different dataloggers or from different visits to the field.

If the SM is just brought to the site to pick-up data, the SC90 Serial Line Monitor can be used to visually confirm that data were transferred. The SC90 contains an LED which lights during data transmission. When the light goes OFF, data transfer is complete and the SM can be disconnected from the CR7.

2. Enter the appropriate commands as listed in Table 4.2-2.

4.4 PRINTER OUTPUT FORMATS

Printer output can be sent in the binary Final Storage Format (Appendix C.2) or Printable ASCII. If using the *4 Mode to enable on-line output, Printable ASCII is the only format available.

In the Printable ASCII format, each data point is preceded by a two digit data point ID and a + or

- sign. The ID and fixed spacing of the data

points make particular points easy to find on a printed output. This format requires 10 bytes per data point to store on disk.

Figure 4.5-1 shows both high and low resolution data points in a 12 data point output array. The example data contains Day, Hour-Minute, and Seconds in the 2nd - 4th data points. The output array ID and time values (year, day, hour-minute, and seconds) are always four character numbers, even when high resolution output is specified.

4.3.3 *9 DUMP TO STORAGE MODULE

In addition to the on-line data output procedures described above, output from CR7 Final Storage to the SM192 and SM716 can be manually initiated in the *9 Mode. The procedure for setting up and transferring data is as follows:

1. Connect the Storage Module to the CR7 using the SC12 cable.

Each full line of data contains eight data points (79 characters including spaces), plus a carriage return (CR) and line feed (LF). If the last data point in a full line is high resolution, it is followed immediately with a CR and LF. If it is low resolution, the line is terminated with a space, CR and LF. Lines of data containing less than eight data points are terminated similarly after the last data point.

4-4

SECTION 4. EXTERNAL STORAGE PERIPHERALS

FIGURE 4.4-1. Example of CR7 Printable ASCII Output Format

4-5

SECTION 4. EXTERNAL STORAGE PERIPHERALS

This is a blank page.

4-6

SECTION 5. TELECOMMUNICATIONS

Telecommunications allows a computer to retrieve data directly from Final Storage and may be used to program the CR7 and monitor sensor readings in real time. Any user communication with the CR7 that makes use of a computer or terminal instead of the CR7 keyboard is through Telecommunications.

Telecommunications can take place over a variety of links including:

• telephone

• radio frequency

• short haul modem

• SC32A and ribbon cable

• multi-drop interface and coax cable

This section does not cover the technical interface details for any of these links. Those details are covered in Section 6 and in the individual manuals for the devices.

Data retrieval can take place in either ASCII or BINARY. The BINARY format is five times more compact than ASCII. The shorter transmission times for binary result in lower long distance telephone charges and more reliable data transfer. On "noisy" links shorter blocks of data are more likely to get through without interruption.

In addition to more efficient data transfer, binary data retrieval makes use of a signature for error detection. The signature algorithm assures a 99.998% probability that if either the data or its sequence changes, the signature changes.

The PC208 Datalogger Support Software for PCs and compatibles contains the programs which automate data retrieval, program transfer, and real time monitoring. The PC208 package has been designed to meet the most common needs in datalogger support and telecommunications. This section in not intended to furnish sufficient detail to write Telecommunications software. Appendix C contains some details of binary data transfer and Campbell Scientific's binary data format.

This section emphasizes the commands that a person would use when manually (i.e., entered by hand) interrogating or programming the CR7 via a computer/terminal. These commands and the responses to them are sent in the American Standard Code for Information Interchange (ASCII). The Remote Keyboard State (Section 5.2) allows the user with a computer/terminal to use the same commands as the CR7 keyboard.

5.1 TELECOMMUNICATIONS

COMMANDS

When the CR7 is rung by a modem, it answers (enables the modem) almost immediately. Several carriage returns (CR) must be sent from the computer to allow the CR7 to set its baud rate to that of the modem/terminal (300, 1200, 9600, or 76,800). Once the baud rate is set, the CR7 sends the prompt, *, signaling that it is ready to receive a command.

GENERAL RULES governing the telecommunications commands are:

1. * from datalogger means "ready for command".

2. All commands are of the form: [no.]letter, where the number may or may not be optional.

3. Valid characters are the numbers 0-9, the capital letters A-L, the colon (:), and the carriage return (CR).

4. An illegal character increments a counter and zeros the command buffer, returning *.

5. CR to datalogger means "execute".

5-1

SECTION 5. TELECOMMUNICATIONS

6. CRLF from datalogger means "executing command".

7. ANY character besides a CR sent to the datalogger with a legal command in its buffer causes the datalogger to abort the command sequence with CRLF* and to zero the command buffer.

8. All commands return a response code, usually at least a checksum.

9. The checksum includes all characters sent by the datalogger since the last *, including the echoed command sequence, excluding only the checksum itself. The checksum is formed by summing the ASCII values, without parity, of the transmitted characters. The largest possible checksum value is

8191. Each time 8191 is exceeded, the CR7 starts the count over; e.g., if the sum of the ASCII values is 8192, the checksum is 0.

10. Commands that return Campbell Scientific binary format data (F and K commands) return a signature (Appendix C).

The CR7 sends ASCII data with eight data bits, no parity, plus one start bit and one stop bit.

After answering a ring, or completing a command, the CR7 waits about 40 seconds

(147 seconds in the Remote Keyboard State) for a valid character to arrive. If a valid character is not received, the CR7 "hangs up". Some modems are quite noisy when not on line; it is possible for valid characters to appear in the noise pattern. To insure that this situation does not keep the CR7 in telecommunications, the CR7 counts all the invalid characters it receives from the time it answers a ring, and terminates communication after receiving 150 invalid characters.

The CR7 continues to execute its measurement and processing tasks while servicing the telecommunication requests. If the processing overhead is large (short execution interval), the processing tasks will slow the telecommunication functions. In a worst case situation, the CR7 interrupts the processing tasks to transmit a data point every 0.1 second.

The best way to become familiar with the Telecommunication Commands is to try them from a terminal connected to the CR7 via the SC32A or other modem interface (Section 6.5). Telecommunications Commands are described in the following Table. The Data Storage Pointer (DSP) and Telecommunications Modem Pointer (MPTR) referred to in the table are described in Section 2.1.

5-2

TABLE 5.1-1. Telecommunications Commands

Command Description

A STATUS - Datalogger returns Reference, the DSP location; the number of

filled Final Storage locations; Version of datalogger; Errors #1 and #2 where #1 is the number of E08 and #2 is the number of overrun that have occurred (cleared by entering 8888A); Memory status, the decimal number (in ASCII characters) that is the equivalent of the 8 bit binary number shown as the result of the memory check on power-up; Location of MPTR; and Checksum. All in the following format:

R+xxxxx F+xxxxx Vx Exx xx Mxxxx L+xxxxx Cxxxx If data are stored while in telecommunications, the A command must be

issued to update the Reference to the new DSP.

[no. of arrays]B BACK-UP - MPTR is backed-up the specified number of output arrays (no

number defaults to 1) and advanced to the nearest start of array. CR7 sends the MPTR Location and Checksum: L+xxxxx Cxxxx

SECTION 5. TELECOMMUNICATIONS

[YR:DAY:HR:MM:SS]C RESET/SEND TIME - If time is entered the time is reset. If only 2 colons

are in the time string, HR:MM:SS is assumed; 3 colons means DAY:HR:MM:SS. If only the C is entered, time is unaltered. CR7 returns year, Julian day, hr:min:sec, and Checksum: Y:xx Dxxxx Txx:xx:xx Cxxxx

[no. of arrays]D ASCII DUMP - If necessary, the MPTR is advanced to the next start of

array. CR7 sends the number of arrays specified (no number defaults to 1) or the number of arrays between MPTR and Reference, whichever is smaller, CRLF, Location, Checksum.

E End call. Datalogger sends CRLF only.

[no. of loc.]F BINARY DUMP - Used in TELCOM (PC208). See Appendix C.

[F.S. loc. no.]G MOVE MPTR - MPTR is moved to specified Final Storage location. The

location number must be entered. CR7 sends Location and Checksum: L+xxxxx Cxxxx

2718H REMOTE KEYBOARD - CR7 sends the prompt ">" and is ready to execute

standard keyboard commands (Section 5.2).

[loc. no.]I Display/change value at Input Storage location. CR7 sends the value

stored at the location. A new value and CR may then be sent. CR7 sends checksum. If no new value is sent (CR only) the location value will remain the same.

3142J TOGGLE FLAGS AND SET UP FOR K COMMAND - Used in the Monitor

Mode and with the Heads Up Display. See Appendix C for details.

K CURRENT INFORMATION - In response to the K command, the CR7

sends datalogger time, user flag status, the data at the input locations requested in the J command, and Final Storage Data if requested by the J command. Used in the Monitor Mode and with Heads Up Display. See Appendix C.

[Password]L Unlocks security (if enabled) to the level determined by the password

entered (See *C Mode, Section 1.7). CR7 sends security level (0-3) and checksum: Sxx Cxxxx

5.2 REMOTE PROGRAMMING OF THE

CR7

The CR7 can be programmed via telecommunications using the PC208 software or manually through the Remote Keyboard State.

The PC208 Datalogger Support Software was developed for use with IBM or compatible PCs.

The CR7 is placed in the Remote Keyboard State by sending "2718H" and a carriage return (CR). The CR7 responds by sending a CR, line feed (LF), and the prompt ">". The CR7 is then ready to receive the standard keyboard

commands (Section OV3); it recognizes all the standard CR7 keyboard characters plus the decimal point. While in the Remote Keyboard State, the CR7 sends the ASCII character control Q (17 decimal) after each user entry. Entering *0 returns the CR7 to the telecommunications command state.

It is important to remember that the Remote Keyboard State is still within Telecommunications. Entering *0 exits the Remote Keyboard and returns the datalogger to the Telecommunications Command State, awaiting another command. So, the user can step back and forth between the

5-3

SECTION 5. TELECOMMUNICATIONS

Telecommunications Command State and the Remote Keyboard State.

Keying *0 will compile and run the CR7 program if program changes have been made. To compile and run the program without leaving the

Telecommunications Remote

Command *0 Keyboard

State State

Remote Keyboard State, use *6 (Section 1.1.4). The CR7 display will show "LOG" when *0 is executed via telecommunications. It will not indicate active tables (enter *0 via the keyboard and the display will show the tables).

2718H

5-4

SECTION 6. CS I/O 9 PIN SERIAL INPUT/OUTPUT

6.1 PIN DESCRIPTION

All external communication peripherals connect to the CR7 through the 9-pin CS I/O connector (Figure 6.1-1). Table 6.1-1 gives a brief description of each pin's function.

FIGURE 6.1-1. CS I/O 9 Pin Connection

CS I/O

TABLE 6.1-1. Pin Description

ABR = Abbreviation for the function name. PIN = Pin number. O = Signal Out of the CR7 to a peripheral. I = Signal Into the CR7 from a peripheral.

PIN ABR I/O Description

1 5V O 5V: Sources 5V DC, used

to power some peripherals.

2 G Ground: Provides a power

return for pin 1 (5V), and is used as a reference for voltage levels.

3 RING I Ring: When raised by a

peripheral the CR7 enters telecommunications.

4 RXD I Receive Data: Serial data

transmitted by a peripheral are received on pin 4.

5 ME O Modem Enable: Raised by

the CR7 after the ring line has been raised.

PIN ABR I/O Description

6 PE O Printer Enable: Raised to

enable Storage Module or

other print device. 7 G I/O Ground, common with pin 2. 8 12 V O 12 volt power for

peripherals. 9 TXD O Transmit Data: Serial data

are transmitted from the

CR7 to peripherals on pin

9; logic low marking (0V)

logic high spacing (5V)

standard asynchronous

ASCII, 8 data bits, no

parity, 1 start bit, 1 stop bit,

300, 1200, 9600, 76,800

baud (user selectable).

6-1

SECTION 6. 9 PIN SERIAL INPUT/OUTPUT

6.2 ENABLING PERIPHERALS

Several peripherals may be connected in parallel to the CS I/O 9-pin port. The CR7 directs data to a particular peripheral by raising the voltage on a specific pin dedicated to the peripheral; the peripheral is enabled when the pin goes high. Two pins are dedicated to specific devices Modem Enable pin 5 and Print Enable pin 6.

Modem Enable (ME), pin 5, is raised to enable a modem that has raised the ring line. Only one modem/terminal may be connected to the CR7.

Print Enable (PE), pin 6, is raised to enable a Storage Module or other print peripheral. Print peripherals are defined as peripherals which have an asynchronous serial communications port used to RECEIVE data transferred by the CR7. In most cases the peripheral is a printer, but could also be an on-line computer or other device. It is possible to have more than one print peripheral connected to the CR7 at one time, as long as they don't load down the TXD line (e.g., two Storage Modules, Section 4.4.1); all connected receive the same data.

6.3 INTERRUPTING DATA TRANSFER TO STORAGE PERIPHERALS

Instruction 96 is used for on-line data transfer to peripherals (Section 4.1). Data transfer is aborted when a modem raises the Ring line and the CR7 then enters Telecommunications (Section 5, 6.4). After the CR7 exits Telecommunications, data transfer to the peripheral is resumed the next time Instruction 96 is executed, or, if activated by the *4 Mode, at the completion of the next active table.

The *8 and *9 Modes are used to position the Memory Pointers, and to manually initiate data transfer from Final Storage to a peripheral. If the # key is pressed during data transfer, the transfer is stopped and the display shows the Final Storage location where the pointer stopped.

6.4 TELECOMMUNICATIONS - MODEM PERIPHERALS

Any serial communication device which raises the Ring line and holds it high until the ME line is raised is a modem. The CSI field modem (DC112, COM200, COM100, or DC1765), RF95 RF modem, MD9 Multi-Drop Interface, and the SC32A RS232 interface used with computers or terminals are modems.

When a modem raises the Ring line, the CR7 responds by raising the ME line. The CR7 must be sent carriage returns until it sets the baud rate. When the baud rate is set, the CR7 sends a carriage return, line feed, *.

The ME line is held high until the CR7 receives an E to exit telecommunications or until a time limit expires without receiving a character. The colon in CR7 display is not shown while the CR7 is in telecommunications.

Some modems are quite noisy when not on line; it is possible for valid characters to appear in the noise pattern. For this reason, the CR7 counts all the invalid characters it receives from the time it answers a ring and terminates communication (lowers the ME line and returns to the *0 Mode) after receiving 150 invalid characters.

6.5 INTERFACING WITH COMPUTERS, TERMINALS, AND PRINTERS

This section deals with some of the basics of serial communication between the CR7 and common computer equipment. If you have an IBM compatible PC, the PC208(W) Datalogger Support Software takes care of the software protocol required in communicating with the CR7. This section does not discuss modem interfaces other than the SC32A. Please refer to the PC208 software and modem operator's manuals for interfacing details on other modems.

Data transfer can be stopped as follows:

1. Printable ASCII - after every output array.

2. Binary - after every Final Storage location.

6-2

SECTION 6. 9 PIN SERIAL INPUT/OUTPUT

6.5.1 SC32A INTERFACE

Most computers, terminals, and printers require the SC32A Optically Isolated RS232 Interface for a "direct" connection to the CR7. The SC32A raises the CR7's ring line when it receives characters from the computer or terminal, and converts the CR7's logic levels (0V logic low, 5V logic high) to RS232 logic levels.

The SC32A 25 pin port is configured as Data Communications Equipment (DCE) which allows direct connection to Data Terminal Equipment (DTE), which includes most PCs and printers. For connection to DCE devices such as modems and some computers, use SC932 interface in place of SC32A.

When the SC32A receives a character from the computer or terminal (pin 2), 5V is applied to the datalogger Ring line (pin 3) for one second or until the Modem Enable line (ME) goes high. The CR7 waits approximately 40 seconds to receive carriage returns, which it uses to establish baud rate. After the baud rate is set the CR7 transmits a carriage return, line feed, *, and enters the Telecommunications Command State (Section 5). If the carriage returns are not received within the 40 seconds, the CR7 "hangs up".

NOTE: The SC32A has a jumper. With the jumper in place, the SC32A blocks printer data and passes data only when the CR7 is in Telecommunications.

6.5.2 COMPUTER/TERMINAL REQUIREMENTS

Computers, terminals and printers are usually configured as Data Terminal Equipment (DTE). Pins 4 and 20 are used as handshake lines, which are set high when the serial port is enabled. Power for the SC32A is taken from these pins. For equipment configured as DTE, a direct ribbon cable connects the modem/terminal to the SC32A. Clear to Send (CTS) pin 5, Data Set Ready (DSR) pin 6, and Received Line Signal Detect (RLSD) pin 8 are held high by the SC32A (when the RS232 section is powered) which should satisfy hardware handshake requirements of the modem/terminal.

TABLE 6.5-1. DTE Pin Configuration

PIN = 25-pin connector number ABR = Abbreviation for the function name O = Signal Out of the terminal to another device I = Signal Into the terminal from another device

PIN ABR I/O FUNCTION

2 TD O Transmitted Data: Data is

transmitted from the terminal on this line.

3 RD I Received Data: Data is

received by the terminal on this line.

4 RTS O Request to Send: The

terminal raises this line to ask a receiving device if the terminal can transmit data.

5 CTS I Clear to Send: The

receiving device raises this line to let the terminal know that the receiving device is ready to accept data.

20 DTR O Data Terminal Ready: The

terminal raises this line to tell the modem to connect itself to the telephone line.

6 DSR I Data Set Ready: The

modem raises this line to tell the terminal that the modem is connected to the phone line.

8 DCD I Data Carrier Detect: The

modem raises this line to tell the terminal that the modem is receiving a valid carrier signal from the phone line.

22 RI I Ring Indicator: The

modem raises this line to tell the terminal that the phone is ringing.

7 SG Signal Ground: Voltages

are measured relative to this point.

Table 6.5-1 lists the most common RS232 configuration for Data Terminal Equipment.

6-3

SECTION 6. 9 PIN SERIAL INPUT/OUTPUT

FIGURE 6.5-1. Transmitting the ASCII Character 1

6.5.3 COMMUNICATION PROTOCOL/TROUBLE SHOOTING

The ASCII standard defines an alphabet consisting of 128 different characters where each character corresponds to a number, letter, symbol, or control code.

An ASCII character is a binary digital code composed of a combination of seven "bits", each bit having a binary state of 1 or more. For example, the binary equivalent for the ASCII character "1" is 0110001 (decimal 49).

ASCII characters are transmitted one bit at a time, starting with the first (least significant) bit. During data transmission the marking condition is used to denote the binary state 1, and the spacing condition for the binary state 0. The signal is considered marking when the voltage is more negative than minus three volts with respect to ground, and spacing when the voltage is more positive than plus three volts.

Most computers use 8-bits (1 byte) for data communications. The eighth bit is sometimes used for a type of error checking called parity checking. Even parity binary numbers have an even number of 1's, odd-parity characters have an odd number of 1's. When parity checking is used, the eighth bit is set to either a 1 or a 0 to make the parity of the character correct. The CR7 ignores the eighth bit of a character that is receives, and transmits the eighth bit as a binary 0. This method is generally described as "no parity".

Figure 6.5-1 shows how the ASCII character "1" is transmitted. The SC32A interface transmits spacing and marking voltages which are positive and negative, as shown. Signal voltages at the CR7 I/O port are 5 volts in the spacing condition, and 0 volts in the marking condition.

BAUD RATE BAUD RATE is the number of bits transmitted

per second. The CR7 can communicate at 300, 1200, 9600, and 76,800 baud. In the Telecommunications State, the CR7 will set its baud rate to match the baud rate of the modem.

The baud rate of the modem or computer is usually set with dip switches or programmed from the keyboard. The instrument's instruction manual should explain how to set it.

DUPLEX Full duplex means that two devices can

communicate in both directions simultaneously. Half duplex means that the two devices must send and receive alternately. Full duplex should always be specified when communicating with Campbell Scientific peripherals and modems. However, communication between some Campbell Scientific modems (such as the RF95 RF modem) is carried out in a half duplex fashion. This can affect the way commands should be sent to and received from such a modem, especially when implemented by computer software.

To separate ASCII characters, a Start bit is sent before the first data bit, and a Stop bit is sent after the eighth data bit. The start bit is always a space, and the stop bit is always a mark. Between characters, the signal is in the marking condition.

6-4

To overcome the limitations of half duplex, some communications links expect a terminal sending data to also write the data to the screen. This saves the remote device having to echo that data back. If, when communicating with a Campbell Scientific device, characters are displayed twice (in pairs), it is likely that the

SECTION 6. 9 PIN SERIAL INPUT/OUTPUT

terminal is set to half duplex rather than the correct setting of full duplex.

IF NOTHING HAPPENS If the CR7 is connected via the SC32A interface

to a terminal or computer and * is not received after sending carriage returns:

1. Verify that the CR7 has power and that the cables connecting the devices are securely connected.

2. Verify that the port of the computer or terminal is an asynchronous serial communications port configured as DTE (see Table 6.5-1). The most common problems occur when the user tries to use a parallel port, or doesn't know the port address (i.e. COM1 or COM2). IBM, and most compatibles come with a Diagnostic disk which can be used to identify ports, and their addresses. If the serial port is standard equipment, then the operators manual should give you this information. Some serial ports such as the Super Serial Card for Apple computers, can be configured as DTE or DCE with a jumper block. Pin functions must match with Table

6.5-1.

If you are using a computer without the PC208 software, then a program or communication software must be used to enable the serial port and to make the computer function as a terminal. The port should be enabled for 300, 1200, or 9600 baud, 8 data bits, 1 stop bit, and no parity.

If you are not sure that your computer or terminal is sending or receiving characters, there is a simple way to verify it. Set the duplex to full. Next, take a paper clip and connect one end to pin 2, and the other end to pin 3 of the serial port. Each character typed on the keyboard will be displayed only if transmitted from the terminal on pin 2, and received on pin 3 (with half duplex the character will be displayed once if it is not transmitted, or twice if it is transmitted).

IF GARBAGE APPEARS If garbage characters appear on the

modem/terminal, check that the modem/terminal's baud rate is supported by the CR7. If the baud rate is correct, verify that the modem/terminal is set for 8 Data bits, and no Parity. Garbage will appear if 7 Data bits and no Parity are used. If the modem/terminal is set to 8 Data bits and even or odd Parity, communication cannot be established.

6-5

SECTION 6. 9 PIN SERIAL INPUT/OUTPUT

This is a blank page.

6-6

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

This section gives some examples of Input Programming for common sensors used with the CR7. These examples detail only the connections, Input, Program Control and Processing Instructions necessary to perform measurements and store the data in engineering units in Input Storage. Output Processing Instructions are omitted, it is left for the user to program the necessary instructions to obtain the final data in the form desired. NO OUTPUT TO FINAL STORAGE WILL TAKE PLACE WITHOUT ADDITIONAL PROGRAMMING.

The examples given in this section would likely be only fragments of larger program tables. In general, the examples are written with the measurements made by the first channels on the first cards in the I/O Module, the instructions at the beginning of a program table, and low number Input Storage locations used to Store the data. Because it is unlikely that an application and CR7 configuration exactly duplicates that assumed in an example, THESE EXAMPLES ARE NOT MEANT TO BE USED VERBATIM; CARDS AND CHANNELS REFERENCED, SENSOR CALIBRATION AND INPUT LOCATIONS SELECTED MUST BE ADJUSTED FOR THE ACTUAL CIRCUMSTANCES. UNLESS OTHERWISE NOTED, ALL EXCITATION CHANNELS ARE SWITCHED ANALOG OUTPUT.

7.1 SINGLE ENDED VOLTAGE - LI200S SILICON PYRANOMETER

The silicon pyranometer puts out a current which is dependent upon the solar radiation incident upon the sensor. The current is measured as the voltage drop across a fixed resistor. The Campbell Scientific LI200S uses a 100 ohm resistor. The calibration supplied by LI-COR, the manufacturers of the pyranometer, is given in uA/kW/m2. The calibration in terms of volts is determined by multiplying the µA calibration by the resistance of the fixed resistor.

The calibration of the pyranometer used in this example is assumed to be 76.9 µA/kW/m2, which when multiplied by 100 ohms equals 7.69 mV/kW/m2. The multiplier used to convert the voltage reading to kW/m2 is 1 / 7.69 mV/kW/m = 0.13004.

Most LI-COR calibrations run between 60 and 90 µA/kW/m2, which correspond to calibrations of 6.0 to 9.0 mV/kW/m2. The flux density through a surface normal to the solar beam above the earth's atmosphere is 1.36 kW/m2; radiation on earth will be less than this. Thus, the 15 mV scale provides an adequate range (9.0 mV/kW/m2 x 1.36 kW/m2 < 15 mV).

CONNECTIONS The pyranometer output is measured with a

single ended voltage measurement on channel

5. There are twice as many single ended

channels as differential channels and they are numbered accordingly: single ended channel 5 is the high side of differential channel 3, and the low side is single ended channel 6.

FIGURE 7.1-1. Wiring Diagram for LI200S

PROGRAM

01: P1 Volt (SE)

01: 1 Rep 02: 3 15 mV slow Range

03: 1 IN Card 04: 5 IN Chan 05: 1 Loc [:R kW/m^2 ] 06: .13004 Mult 07: 0 Offset

7.2 DIFFERENTIAL VOLTAGE MEASUREMENT

Some sensors either contain or require active signal conditioning circuitry to provide an easily measured analog voltage output. Generally, the output is referenced to the sensor ground. The associated current drain usually requires a power source external to the CR7. A typical connection scheme where AC power is not available and both the CR7 and sensor are powered by an external battery is shown in

7-1

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

Figure 7.2-1. Since a single ended measurement is referenced to the CR7 ground, any voltage difference between the sensor ground and CR7 ground becomes a measurement error. A differential measurement avoids this error by measuring the signal between the 2 leads without reference to ground. This example analyzes the potential error on a water pH measurement using a Martek Mark V water quality analyzer.

FIGURE 7.2-1. Typical Connection for Active

Sensor with External Battery

The wire used to supply power from the external battery is 18 AWG with an average resistance of 6.5 ohms/1000 ft. The power runs to the CR7 and pH meter are 2 ft. and 10 ft., respectively. Typical current drain for the pH meter is 300 mA. When making measurements, the CR7 draws about 100 mA. Since voltage is equal to current times resistance (V=IR), ground voltages at the pH meter and the CR7 relative to battery ground are:

pH meter ground =

0.3A x 10/1000 x 6.5 Ohms = +0.0195V CR7 ground =

0.1A x 2/1000 x 6.5ohms = +0.0013V

Ground at the pH meter is 0.0182V higher than ground at the CR7. The meter output is 0-1 volt referenced to meter ground, for the full range of 14 pH units, or 0.0714V/pH. Thus, if the output is measured with a single ended voltage measurement, it is 0.0182V or 0.25 pH units too high. If this offset remained constant, it could be corrected in programming the CR7. However, it is better to use a differential voltage measurement which does not rely on the current drain remaining constant. The Program that follows illustrates the use of Instruction #2 to make the measurement. A multiplier of

0.014 is used to convert the millivolt output into pH units.

PROGRAM

01: P2 Volt (DIFF)

01: 1 Rep 02: 7 1500 mV slow Range 03: 1 IN Card 04: 1 IN Chan 05: 1 Loc [:pH ] 06: 0.014 Mult 07: 0 Offset

7.3 THERMOCOUPLE TEMPERATURES USING 723-T REFERENCE

The use of the 723-T Analog Input Card RTD to measure the reference temperature is described in the introductory programming example (Section OV4).

7.4 THERMOCOUPLE TEMPERATURES USING AN EXTERNAL REFERENCE JUNCTION

When a number of thermocouple measurements are made at some distance from the CR7, it is often better to use a reference junction box located at the site rather than using the panel temperature of the CR7. This reduces the required length of expensive thermocouple wire as regular copper wire can be used between the junction box (J-box) and CR7. In addition, if the temperature gradient between the J-box and the thermocouple measurement junction is smaller than the gradient between the CR7 and the measurement junction, thermocouple inaccuracy is reduced. In the following example, an external reference junction is used on ten thermocouple measurements. A Campbell Scientific 107 Temperature Probe is used to measure the reference temperature. The connection scheme is shown in Figure 7.4-1.

FIGURE 7.4-1. Thermocouples with External

Reference Junction

7-2

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

The temperature of the 107 Probe is stored in Input Location 1 and the thermocouple temperatures in Locations 2-11.

PROGRAM

01: P11 Temp 107 Probe

01: 1 Rep 02: 1 IN Card 03: 21 IN Chan 04: 1 EX Card 05: 1 EX Chan 06: 1 Loc [:Ref. Temp] 07: 1 Mult 08: 0 Offset

02: P14 Thermocouple Temp (DIFF)

01: 10 Reps 02: 3 15 mV slow Range 03: 1 IN Card 04: 1 IN Chan 05: 1 Type T (Copper-Constantan) 06: 1 Ref Temp Loc Ref. Temp 07: 2 Loc [:TC temp#1] 08: 1 Mult 09: 0 Offset

7.5 THERMOCOUPLES FOR DIFFERENTIAL TEMPERATURE MEASUREMENT

When configured correctly, thermocouples are capable of measuring small temperature gradients very accurately (Section 13.4). In this example, the CR7 is used to make five differential temperature measurements with chromel-constantan thermocouples. The connections are shown in Figure 7.5-1 where the voltage measured between the chromel leads is proportional to the temperature difference between junctions R and D.

When the temperatures are within the reference junction compensation range (Table 13.4-3), three instructions are required in the measurement sequence:

1. A CR7 Panel Temperature Measurement (#17) used as a reference temperature for the measurement at R.

2. A single ended TC measurement (#13) of R temperatures to be used as reference temperatures for the measurement D.

3. A differential TC measurement of D temperatures where the reference temperature at R are subtracted from the results as specified in Parameter 5.

The connection shown in Figure 7.4-1 yields the conventional polarity (sign) for the temperature difference, i.e., D>R=+T, D<R=-T. Using R as the reference temperature maintains this convention whereas using D reverses the sign of the output.

Prefixing a 2 onto the TC type in Parameter 5 of Instruction 13 causes the CR7 to skip every other single ended channel. Keying C before entering Parameter 6 in Instruction 14 causes the reference temperature location to be incremented each rep.

The ±5mV range used in Instruction 13 allows measurement of temperatures at R within a range of approximately ±80 oC of the I/O Module temperature. The ±1.5mV range used in Instruction 14 allows the temperature difference between D and R to approach a range of ±24

C, for temperatures around 25 oC (output = 61 uV/oC). The resolution of the differential temperature measurement is approximately

0.0008 oC (50 nV/61µV/oC).

FIGURE 7.5-1. Connection for

Thermocouple Differential Temperature

Measurement

The panel temperature is stored in Input Location 1, the temperatures of the R junctions in locations 2-6 and the temperature differences (D-R) in locations 7-11. If it is not necessary to retain the temperatures of the R junctions, the temperature differences could be stored in locations 2-6 by changing Parameter #7 in Instruction 14 to 2.

7-3

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

PROGRAM

01: P17 Panel Temperature

01: 1 IN Card 02: 1 Loc [:PANL TEMP]

02: P13 Thermocouple Temp (SE)

01: 5 Reps 02: 2 5000 uV slow Range 03: 1 IN Card 04: 2 IN Chan 05: 22 Type E (Skip every other chan) 06: 1 Ref Temp Loc PANL TEMP 07: 2 Loc [:S.E. T#1 ] 08: 1 Mult 09: 0 Offset

03: P14 Thermocouple Temp (DIFF)

01: 5 Reps 02: 1 1500 uV slow Range 03: 1 IN Card 04: 1 IN Chan 05: 12 Type E (Temp difference) 06: 2-- Ref Temp Loc S.E. T#1 07: 7 Loc [:DIFF T #1] 08: 1 Mult 09: 0 Offset

When the temperature of the R junction is outside of the CR7 reference junction compensation range (Table 13.4-3), the TCs must be connected in the normal fashion, one TC per input channel; both temperatures measured and one subtracted from the other to find the difference. This must be done because any error in the reference junction compensation becomes an error in the temperature difference.

7.6 TEMPERATURE WITH CALIBRATED THERMOCOUPLES

Thermocouple calibration (Section 13.4) results in a slope correction. The correction must be applied only to the thermocouple output. When Instructions 13 and 14 are used to measure temperature, the temperature is the sum of the reference temperature and the temperature difference calculated from the thermocouple output. The correction must be applied to the temperature difference before the reference temperature is added.

Example A demonstrates the use of a scaling array (Instruction 53) to correct the calibration of four individually calibrated thermocouples.

Another means of applying a correction factor to a number of thermocouples is to group together those with a similar correction factor. In example B, the slope correction factor for a group of 5 thermocouples is entered as the multiplier (Parameter 8) in the instruction to read those thermocouples. The example only shows one group of thermocouples. If there were several groups with similar correction factors, Instruction 14 would be used to read and correct each group.

After the slope correction is made, a loop is used to add the reference temperature to the corrected temperature differences.

CONNECTIONS The thermocouples are connected in the normal

manner: chromel to Hi and constantan to Low. In both examples, the first thermocouple is connected to Channel 1. Care must be taken that the correction factors called for in the programming match the channels that the calibrated thermocouples are connected to.

PROGRAM A

01: P17 Panel Temperature

01: 1 IN Card 02: 1 Loc [:REF TEMP ]

02: P14 Thermocouple Temp (DIFF)

01: 4 Reps 02: 3 15 mV slow Range 03: 1 IN Card 04: 1 IN Chan 05: 12 Type E (Temp difference) 06: 1 Ref Temp Loc REF TEMP 07: 2 Loc [:TC temp#1] 08: 1 Mult 09: 0 Offset

03: P53 Scaling Array (A*loc +B)

01: 2 Start Loc [:TC temp#1] 02: .99255 A1 03: 0 B1 04: .99703 A2 05: 0 B2 06: 1.0045 A3 07: 0 B3 08: 1.0075 A4 09: 0 B4

7-4

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

04: P87 Beginning of Loop

01: 0 Delay 02: 4 Loop Count

05: P33 Z=X+Y

01: 1 X Loc REF TEMP 02: 2-- Y Loc TC temp#1 03: 2-- Z Loc [:TC temp#1]

06: P95 End

PROGRAM B

01: P17 Panel Temperature

01: 1 IN Card 02: 1 Loc [:REF TEMP ]

02: P14 Thermocouple Temp (DIFF)

01: 5 Reps 02: 3 15 mV slow Range 03: 1 IN Card 04: 1 IN Chan 05: 12 Type E (Temp difference) 06: 1 Ref Temp Loc REF TEMP 07: 2 Loc [:TC temp#1] 08: .99253 Mult 09: 0 Offset

If there were additional groups of thermocouples, the Instructions to measure them would be inserted here and Parameter 2 in Instruction 87 adjusted accordingly.

03: P87 Beginning of Loop

01: 0 Delay 02: 5 Loop Count

04: P33 Z=X+Y

01: 1 X Loc REF TEMP 02: 2-- Y Loc TC temp#1 03: 2-- Z Loc [:TC temp#1]

CONNECTIONS The black leads from the probes go to excitation

channel 1, the white leads go to ground, and the red leads go to single ended channels 1, 2, and 3 (high and low sides of differential channel 1 and high side of 2).

PROGRAM

01: P11 Temp 107 Probe

01: 3 Reps 02: 1 IN Card 03: 1 IN Chan 04: 1 EX Card 05: 1 EX Chan 06: 1 Loc [:107 T #1 ] 07: 1 Mult 08: 0 Offset

7.8 207 TEMPERATURE AND RH PROBE

Instruction 12 excites and measures the RH portion of the Campbell Scientific 207 temperature and relative humidity probe. This instruction relies on a previously measured temperature to compute the RH from the probe resistance. Instruction 12 has the option of using a single temperature to provide the compensation reference for several RH probes. In this example, three probes will be measured; the temperature of each probe will be measured and used to provide temperature compensation for that probe. Instruction 11 is used to obtain the temperatures of the three probes which are stored in Input locations 1-3, the RH values are stored in Input locations 4-6. The temperature measurements are made on single ended input channels 1-3, just as in example 7.7. The program listed below is a continuation of the program given in example 7.7.

05: P95 End

7.7 107 TEMPERATURE PROBE

Instruction 11 is designed to excite and measure the Campbell Scientific 107 thermistor probe (or the thermistor portion of the 207 temperature and relative humidity probe) and convert the measurement into temperature (oC). In this example, the temperatures are obtained from three 107 probes. The measurements are made on single ended channels 1-3, and the temperatures are stored in Input locations 1-3.

CONNECTIONS The black leads from the probes are connected

to excitation channel 1, the clear leads are connected to ground. The red leads are from the thermistor circuit and are connected to single ended channels 1-3. The white leads are from the RH circuit and are connected to single ended channels 4-6. The correct order must be maintained when connecting the red and white leads, i.e., the red lead from the first probe is connected to single ended channel 1 and the white lead from that probe is connected to single ended channel 4, etc.

7-5

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

PROGRAM

02: P12 RH 207 Probe

01: 3 Reps 02: 1 IN Card 03: 4 IN Chan 04: 1 EX Card 05: 1 EX Chan 06: 1 Meas/Temp 07: 1 Temperature Loc 207 T#1 08: 4 Loc [:RH #1 ] 09: 1 Mult 10: 0 Offset

7.9 ANEMOMETER WITH PHOTOCHOPPER OUTPUT

An anemometer with a photochopper transducer produces a pulsed output which is monitored with the Pulse Count Instruction, configured for High Frequency Pulses. The Pulse Count Instruction counts the number of pulses occurring in each execution interval. An option in the instruction allows this to be converted to frequency in Hertz (i.e., Pulses/Second). The anemometer used in this example is the R. M. Young Model No. 12102D Cup Anemometer, with a 10 window chopper wheel. The photochopper circuitry is powered from the CR7 12V supply; AC power or backup batteries should be used to compensate for the increased current drain.

Wind speed is desired in meters per second. There is a pulse each time a window in the chopper wheel, which revolves with the cups, allows light to pass from the source to the photoreceptor. Because there are 10 windows in the chopper wheel, there are 10 pulses per revolution. Thus, 1 rpm is equal to 10 pulses per 60 seconds (1 minute) or 6 rpm = 1 pulse per second. The manufacturer's calibration for relating wind speed to rpm is:

The multiplier and offset to convert pulses per second to meters per second are:

m/s =

0.01632 m/s/rpm x 6 rpm/(pulse/s) + 0.2 m/s = 0.0979 m/s/pulse x

pulses + 0.2 m/s

There are occasionally times when the CR7's CPU is occupied and does not reset the pulse counters at the exact time interval programmed. If the artificially large wind speed that results from a long interval is used, it causes a false average or maximum value. To avoid this, the CR7 is instructed to discard values resulting from long intervals, and use the previous value instead.

FIGURE 7.9-1. Wiring Diagram for

Anemometer

PROGRAM

(Execution interval 10 seconds)

01: P3 Pulse

01: 2 Reps 02: 2 IN Card 03: 2 Pulse Input Chan 04: 20 High frequency; Output Hz. 05: 10 Loc [:WS m/s ] 06: .0979 Mult 07: .2 Offset

7.10 TIPPING BUCKET RAINGAGE WITH LONG LEADS

7-6

Wind speed (m/s) =

0.01632 m/s/rpm x rpm +0.2 m/s

A tipping bucket raingage is measured with the Pulse Count Instruction configured for Switch Closure. Counts from long intervals will be used, as the final output desired is total rainfall (obtained with Instruction 72, Totalize). If counts from long intervals were discarded, less rainfall would be recorded than was actually measured by the gage (assuming there were counts in the long intervals). Output is desired in millimeters of precipitation; the gage is calibrated for a 0.01 inch tip so a multiplier of

0.254 is used.

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

FIGURE 7.10-1. Wiring Diagram for

Raingage with Long Leads

In a long cable, there is appreciable capacitance between the lines which is discharged across the switch when it closes. In addition to shortening switch life, a transient may be induced in other wires, packaged with the rain gage leads, each time the switch closes. The 100 ohm resistor protects the switch from arcing and the associated transient from occurring, and should be included any time leads longer than 100 ft. are used with a switch closure.

PROGRAM

01: P3 Pulse

01: 1 Rep 02: 2 IN Card 03: 1 Pulse Input Chan 04: 2 Switch closure 05: 11 Loc [:RAIN mm ] 06: 0.254 Mult 07: 0 Offset

Figure 7.11-1 diagrams the circuit used to measure the PRT. The 10 kohm resistor allows the use of a high excitation voltage and low voltage ranges on the measurements. This insures that noise in the excitation does not have an effect on signal noise. Because the fixed resistor (Rf) and the PRT (Rs) have approximately the same resistance, the differential measurement of the voltage drop across the PRT can be made on the same range as the differential measurement of the voltage drop across Rf. The use of the same range eliminates any range translation error that might arise from the 0.01% tolerance of the range translation resistors in the CR7.

If the voltage drop across the PRT (V2) is kept on the 50 mV range, self heating of the PRT should be less than 0.001 oC in still air. The resolution of the measurement is increased as the excitation voltage (Vx) is increased. The voltage drop across the PRT is equal to V multiplied by the ratio of Rs to the total resistance, and is greatest when Rs is greatest (Rs=115.54 ohms at 40 oC). To find the maximum excitation voltage that can be used, we assume V2 equal to 50 mV and use Ohm's Law to solve for the resulting current, I.

I = 50mV/Rs = 50mV/115. 54 Ohms = 0.433mA Next solve for Vx:

7.11 100 OHM PRT IN 4 WIRE HALF BRIDGE

Instruction 9 is the best choice for accuracy where the Platinum Resistance Thermometer (PRT) is separated from other bridge completion resistors by a lead length having more than a few thousandths of an ohm resistance. In this example, it is desired to measure a temperature in the range of -10 to 40 oC. The length of the cable from the CR7 to the PRT is 500 feet.

FIGURE 7.11-1. Wiring Diagram for PRT in 4

Wire Half-Bridge

Vx = I(R1+Rs+Rf) = 4.42V

If the actual resistances were the nominal values, the CR7 would not overrange with Vx =

4.4 V. To allow for the tolerances in the actual resistances it is decided to set Vx equal to 4.2 volts (e.g., if the 10 kohms resistor is 5% low, Rs/(R1+Rs+Rf)=115.54/9715.54 and Vx must be 4.204V to keep Vs less than 50 mV).

The result of Instruction 9 when the first differential measurement (V1) is not made on the 5V range is equivalent to Rs/Rf. Instruction 16 computes the temperature (oC) for a DIN 43760 standard PRT from the ratio of the PRT resistance to its resistance at 0 oC (Rs/R0). Thus, a multiplier of Rf/R0 is used in Instruction 9 to obtain the desired intermediate, Rs/R0 (= Rs/Rf x Rf/R0). If Rs and R0 were each exactly 100 ohms the multiplier would be 1. However, neither resistance is likely to be exact. The correct multiplier is found by connecting the PRT to the CR7 and entering Instruction 9 with

7-7

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

a multiplier of 1. The PRT is then placed in an ice bath (0 oC; Rs=R0), and the result of the bridge measurement is read using the *6 Mode. The reading is Rs/Rf, which is equal to R0/R since Rs = R0, the correct value of the multiplier, Rf/R0, is the reciprocal of this reading. The initial reading assumed for this example was 0.9890, the correct multiplier is: Rf/R0 = 1/0.9890 = 1.0111.

The fixed 100 ohm resistor must be thermally stable. Its precision is not important because the exact resistance is incorporated, along with that of the PRT, into the calibrated multiplier. The 10 ppm/oC temperature coefficient of the fixed resistor will limit the error due to its change in resistance with temperature to less than 0.15

C over the specified temperature range. Because the measurement is ratiometric (Rs/Rf), the properties of the 10 kohm resistor do not affect the result.

Figure 7.12-1. 3 Wire Half-Bridge Used to

As in the example in section 7.11, the excitation voltage is calculated to be the maximum possible yet allow the ±50 mV measurement range. The 10 kohm resistor has a tolerance of ±1%, thus, the lowest resistance to expect from it is 9.9 kohms. We calculate the maximum excitation voltage (Vx) to keep the voltage drop across the PRT less than 50 mV:

0.050V > Vx 115.54/(9900+115.54); Vx < 4.33V

Measure 100 ohm PRT

PROGRAM

01: P9 Full BR w/Compensation

01: 1 Rep 02: 4 50 mV slow EX Range 03: 4 50 mV slow BR Range 04: 1 IN Card 05: 1 IN Chan 06: 1 EX Card 07: 1 EX Chan 08: 1 Meas/EX 09: 4200 mV Excitation 10: 1 Loc [:Rs/Ro ] 11: 1.0111 Mult 12: 0 Offset

02: P16 Temperature RTD

01: 1 Rep 02: 1 R/Ro Loc Rs/Ro 03: 2 Loc [:TEMP degC] 04: 1 Mult 05: 0 Offset

7.12 100 OHM PRT IN 3 WIRE HALF BRIDGE

The temperature measurement requirements in this example are the same as in section 7.11. In this case a three wire half bridge, Instruction 7, is used to measure the resistance of the PRT. The diagram of the PRT circuit is shown in Figure 7.12-1.

The excitation voltage used is 4.3V. The multiplier used in Instruction 7 is

determined in the same manner as in section

7.11. In this example the multiplier (Rf/R0) is assumed to be 100.93.

The 3 wire half bridge compensates for lead wire resistance by assuming that the resistance of wire A is the same as the resistance of wire B. The maximum difference expected in wire resistance is 2%, but is more likely to be on the order of 1%. The resistance of Rs calculated with Instruction 7, is actually Rs plus the difference in resistance of wires A and B. The average resistance of 22 AWG wire is 16.5 ohms per 1000 feet, which would give each 500 foot lead wire a nominal resistance of 8.3 ohms. Two percent of 8.3 ohms is 0.17 ohms. Assuming that the greater resistance is in wire B, the resistance measured for the PRT (R0 = 100 ohms) in the ice bath would be 100.17 ohms, and the resistance at 40 oC would be

115.71. The measured ratio Rs/R0 is 1.1551, the actual ratio is 115.54/100 = 1.1554. The temperature computed by Instruction 17 from the measured ratio would be about 0.1 oC lower than the actual temperature of the PRT. This source of error does not exist in the example in section 7.11, where the 4 wire half bridge is used to measure PRT resistance.

7-8

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

The advantages of the 3 wire half bridge are that it only requires 3 lead wires going to the sensor, and takes 2 single ended input channels whereas the 4 wire half bridge requires 2 differential input channels.

PROGRAM

01: P 7 3 Wire Half Bridge

01: 1 Rep 02: 4 50 mV slow Range 03: 1 IN Card 04: 1 IN Chan 05: 1 EX Card 06: 1 EX Chan 07: 1 Meas/EX 08: 4300 mV Excitation 09: 1 Loc [:Rs/Ro ] 10: 100.93 Mult 11: 0 Offset

02: P 16 Temperature RTD

01: 1 Rep 02: 1 R/Ro Loc Rs/Ro 03: 2 Loc [:TEMP degC] 04: 1 Mult 05: 0 Offset

7.13 100 OHM PRT IN 4 WIRE FULL BRIDGE

This example describes obtaining the temperature from a 100 ohm PRT in a 4 wire full bridge (Instruction 6). The temperature being measured is in a constant temperature bath and is to be used as the input for a control algorithm. The PRT in this case does not adhere to the DIN standard (alpha = 0.00385) used in the temperature calculating Instruction

16. Alpha is defined as (R R

and R0 are the resistances of the PRT at

100

100 oC and 0 oC, respectively. In this PRT alpha is equal to 0.00392.

100/R0

-1)/100 where

The result given by Instruction 6 (X) is 1000 Vs/Vx (where Vs is the measured bridge output voltage and Vx is the excitation voltage) which is:

X = 1000 (Rs/(Rs+R1)-R3/(R2+R3))

The resistance of the PRT (Rs) is calculated with the Bridge Transform Instruction 59:

Rs = R1 X'/(1-X')

Where

X' = X/1000 + R3/(R2+R3)

Thus, to obtain the value Rs/R0, (R0 = Rs @ 0oC) for the temperature calculating Instruction 16, the multiplier and offset used in Instruction 6 are 0.001 and R3/(R2+R3), respectively. The multiplier used in Instruction 59 to obtain Rs/R is R1/R0 (5000/100 = 50).

It is desired to control the temperature bath at 50oC with as little variation as possible. High resolution is desired so the control algorithm will be able to respond to minute changes in temperature. The highest resolution is obtained when the temperature range results in an output voltage (Vs) range which fills the measurement range selected in Instruction 6. The full bridge configuration allows the bridge to be balanced (Vs = 0V) at or near the control temperature. Thus, the output voltage can go both positive and negative as the bath temperature changes, allowing the full use of the measurement range.

The resistance of the PRT is approximately

119.6 ohms at 50 oC. The 120 ohm fixed resistor balances the bridge at approximately 51

C. The output voltage is:

Vs = Vx [Rs/(Rs+R1) - R3/(R2+R3)]

FIGURE 7.13-1. Full Bridge Schematic For

100 Ohm PRT

= Vx [Rs/(Rs+5000) - 0.023438]

The temperature range to be covered is 50 +5oC. At 45 oC Rs is approximately 117.6 ohms, or:

Vs = -458.448x10-6 V

Vs can be measured on the ±1500 µV scale. Setting Vs equal to -1500 µV and solving for V results in Vx = 3.272 V. Vx is entered as 3270 mV in Parameter 8 of Instruction 6.

7-9

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

The 5 ppm/oC temperature coefficient of the fixed resistors was chosen so that their 0.01% accuracy tolerance would hold over the desired temperature range.

There is a change of approximately 1500 µV from the output at 45 oC to the output at 51 oC, or 250 µV/oC. With a resolution of 50 nV on the 1500 µV range, this means that the temperature resolution is 0.0002 oC.

The relationship between temperature and PRT resistance is a slightly nonlinear one. Instruction 16 computes this relationship for a DIN standard PRT where the nominal temperature coefficient is 0.00385/oC. The change in nonlinearity of a PRT with the temperature coefficient of 0.00392/oC is minute compared with the slope change. Entering a slope correction factor of 0.00385/0.00392 =

0.98214 as the multiplier in Instruction 16 results in a calculated temperature which is well within the accuracy specifications of the PRT.

PROGRAM

01: P6 Full Bridge

01: 1 Rep 02: 1 1500 uV slow Range 03: 1 IN Card 04: 3 IN Chan 05: 1 EX Card 06: 1 EX Chan 07: 1 Meas/EX 08: 3270 mV Excitation 09: 11 Loc [:Rs/Ro ] 10: .001 Mult 11: .02344 Offset

02: P59 BR Transform Rf[X/(1-X)]

01: 1 Rep 02: 11 Loc [:Rs/Ro ] 03: 50 Multiplier (Rf)

7.14 PRESSURE TRANSDUCER - 4 WIRE FULL BRIDGE

This example describes a measurement made with a Druck PDCR 10/D depth measurement pressure transducer. The pressure transducer was ordered for use with 5 volt positive or negative excitation (passive temperature compensation) and has a range of 5 psi or about 3.5 meters of water. The transducer is used to measure the depth of water in a stilling well.

Instruction 6, 4 wire full bridge, is used to measure the pressure transducer. The high output of the semiconductor strain gage necessitates the use of the 50mV input range. The sensor is calibrated by connecting it to the CR7 and using Instruction 6 with a multiplier of 1 and an offset of 0, noting the readings (*6 Mode) with 10 cm of water above the sensor and with 334.6 cm of water above the sensor. The output of Instruction 6 is 1000 Vs/Vx or millivolts per volt excitation. At 10 cm the reading is 0.19963 mV/V and at 334.6 cm the reading is 6.6485 mV/V. The multiplier to yield output in cm is:

(334.6 - 10)/(6.6485-.19963) = 50.334 cm/mV/V The offset is determined after the pressure

transducer is installed in the stilling well. The sensor is installed 65 cm below the water level at the time of installation. The depth of water at this time is determined to be 72.6 cm relative to the desired reference. When programmed with the multiplier determined above and an offset of 0, a reading of 65.12 is obtained. The offset for the actual measurements is thus determined to be 72.6 - 65.12 = 7.48 cm.

The lead length is approximately 10 feet, so there is no appreciable error due to lead wire resistance.

03: P16 Temperature RTD

01: 1 Rep 02: 11 R/Ro Loc Rs/Ro 03: 12 Loc : 04: .98214 Mult 05: 0 Offset

7-10

FIGURE 7.14-1. Wiring Diagram for Full

Bridge Pressure Transducer

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

PROGRAM

01: P6 Full Bridge

01: 1 Rep 02: 4 50 mV slow Range 03: 1 IN Card 04: 1 IN Chan 05: 1 EX Card 06: 1 EX Chan 07: 1 Meas/EX 08: 5000 mV Excitation 09: 13 Loc [:HEIGHT cm] 10: 50.334 Mult 11: 7.48 Offset

7.15 LYSIMETER - 6 WIRE LOAD CELL

When a long cable is required between a load cell and the CR7, the resistance of the wire can create a substantial error in the measurement if the 4 wire full bridge (Instruction 6) is used to excite and measure the load cell. This error arises because the excitation voltage is lower at the load cell than at the CR7 due to voltage drop in the cable. The 6 wire full bridge (Instruction 9) avoids this problem by measuring the excitation voltage at the load cell. This example shows the errors one would encounter if the actual excitation voltage was not measured and shows the use of a 6 wire full bridge to measure a load cell on a weighing lysimeter (a container buried in the ground, filled with plants and soil, used for measuring evapotranspiration).

FIGURE 7.15-1. Diagrammatic

Representation of Lysimeter Weighing

Mechanism

There is 1000 feet of 22 AWG cable between the CR7 and the load cell. The output of the load cell is directly proportional to the excitation voltage. When Instruction 6 (4 wire 1/2 bridge) is used, the assumption is that the voltage drop in the connecting cable is negligible. The average resistance of 22 AWG wire is 16.5 ohms per 1000 feet. Thus, the resistance in the excitation lead going out to the load cell added to that in the lead coming back to ground is 33 ohms. The resistance of the bridge in the load cell is 350 ohms. The voltage drop across the load cell is equal to the voltage at the CR7 multiplied by the ratio of the load cell resistance Rs, to the total resistance, RT, of the circuit. If Instruction 6 were used to measure the load cell, the excitation voltage actually applied to the load cell, V1 would be:

The lysimeter is 2 meters in diameter and 1.5 meters deep. The total weight of the lysimeter with its container is approximately 8000 kg. The lysimeter has a mechanically adjustable counterbalance, and changes in weight are measured with a 250 pound (113.6 kg) capacity Sensotec Model 41 tension/compression load cell. The load cell has a 4:1 mechanical advantage on the lysimeter (ie., a change of 4 kg in the mass of the lysimeter will change the force on the load cell by 1 kg-force or 980 N).

The surface area of the lysimeter is 3.1416 m or 31,416 cm2, so 1 cm of rainfall or evaporation results in a 31.416 kg change in mass. The load cell can measure ±113.6 kg, a 227 kg range. This represents a maximum change of 909 kg, or 28 cm of water in the lysimeter before the counterbalance would have to be readjusted.

V1 = Vx Rs/RT = Vx 350/(350+33) = 0.91 V

Where Vx is the voltage applied at the excitation card. This means that the voltage output by the load cell would only be 91% of that expected. If recording of the lysimeter data was initiated with the load cell output at 0 volts, and 100 mm of evapotranspiration had occurred, calculation of the change with Instruction 6 would indicate that only 91 mm of water had been lost. Because the error is a fixed percentage of the output, the actual magnitude of the error increases with the force applied to the load cell. If the resistance of the wire was constant, one could correct for the voltage drop with a fixed multiplier. However, the resistance of copper changes 0.4% per oC change in temperature. Assume that the cable between the load cell and the CR7 lays on the soil surface and undergoes a 25 oC diurnal temperature fluctuation. If the resistance is 33

7-11

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

ohms at the maximum temperature, then, at the minimum temperature, the resistance is:

(1-25x0.004)33 ohms = 29.7 ohms

The actual excitation voltage at the load cell is:

V1 = 350/(350+29.7) Vx = .92 V

The excitation voltage has increased by 1%, relative to the voltage applied at the CR7. In the case where we were recording a 91 mm change in water content, there would be a 1 mm diurnal change in the recorded water content that would actually be due to the change in temperature. Instruction 9 solves this problem by actually measuring the voltage drop across the load cell bridge. The drawbacks to using Instruction 9 are that it requires an extra differential channel and the added expense of a 6 wire cable. In this case the benefits are worth the expense.

The load cell has a nominal full scale output of 3 millivolts per volt excitation. If the excitation is 5 volts, the full scale output is 15 millivolts; thus the ±15 millivolt range is selected. The calibrated output of the load cell is 3.106 mV/V at a load of 250 pounds. Output is desired in millimeters of water, with respect to a fixed point. The calibration in mV/V1/mm is :

started at the beginning of what is expected to be a period during which evapotranspiration exceeds precipitation. Instruction 9 is programmed with the correct multiplier and no offset. After hooking everything up, the counterbalance is adjusted so that the load cell is near the top of its range, this will allow a longer period before readjustment is necessary. The result of Instruction 9 (monitored with the *6 Mode) is 109. The offset needed to give the desired initial value of 375mm is 266. However, it is decided to add this offset in a separate program so that the result of Instruction 9 can be used as a ready reminder of the strain on the load cell (range = ±140mm). When the strain on the load cell nears its rated limits, the counterbalance is readjusted and the offset recalculated to provide a continuous record of the water budget.

The program table has an execution interval of 10 seconds. The average value in millimeters is output to Final Storage (not shown in Table) every hour. The average is used, instead of a sample, in order to cancel out the effects of wind loading on the lysimeter.

3.106mV/V1/250lb x 2.2lb/kg x

3.1416kg/mm/4 =

0.02147mV/V1/mm

The reciprocal of this gives the multiplier to convert mV/V1 into millimeters (the result of Instruction 9 is the ratio of the output voltage to the actual excitation voltage multiplied by 1000, which is mV/V1):

1/0.02147mV/V1/mm = 46.583 mm/mV/V

The output from the load cell is connected so that the voltage increases as the mass of the lysimeter increases (if the actual mechanical linkage was as diagrammed in Figure 7.15-1, the output voltage would be positive when the load cell was under tension).

When the experiment is started, the water content of the soil in the lysimeter is approximately 25% on a volume basis. It is decided to use this as the reference, (i.e., 0.25 x 1500mm = 375 mm). The experiment is

FIGURE 7.15-2. 6 Wire Full Bridge

Connection for Load Cell

PROGRAM

01: P9 Full BR w/Compensation

01: 1 Rep 02: 8 5000 mV slow EX Range 03: 3 15 mV slow BR Range 04: 1 IN Card 05: 1 IN Chan 06: 1 EX Card 07: 1 EX Chan 08: 1 Meas/EX 09: 5000 mV Excitation 10: 1 Loc [:mm RAW ] 11: 46.583 Mult 12: 0 Offset

7-12

02: P34 Z=X+F

01: 1 X Loc mm RAW 02: 266 F 03: 2 Z Loc [:mm CORECT]

7.16 227 GYPSUM SOIL MOISTURE BLOCK

Soil moisture is measured with a gypsum block by relating the change in moisture to the change in resistance of the block. An AC Half Bridge (Instruction 5) is used to determine the resistance of the gypsum block. Rapid reversal of the excitation voltage inhibits polarization of the sensor. Polarization creates an error in the output so the fast integration time is used. The output of Instruction 5 is the ratio of the midbridge voltage to the excitation voltage, this output is converted to gypsum block resistance with Instruction 59, Bridge Transform.

The Campbell Scientific 227 Soil Moisture Block uses a Delmhorst gypsum block with a 1 kohm bridge completion resistor. Using data supplied by Delmhorst, Campbell Scientific has computed coefficients for a 5th order polynomial to convert block resistance to water potential in bars. There are two polynomials, one to optimize the range from -0.1 to -2 bars and one to cover the range from -0.1 to -15 bars (the minus sign is omitted in the output). The -0.1 to

-2 bar polynomial requires a multiplier of 1 in the Bridge Transform Instruction (result in Kohms) and the -0.1 to -15 bar polynomial requires a multiplier of 0.1 (result in 10,000s of ohms). The multiplier is a scaling factor to maintain the maximum number of significant digits in the coefficients of the polynomial.

In this example, we wish to make measurements on 12 gypsum blocks and output the final data in bars. The soil where the moisture measurements are to be made is quite wet at the time the data logging is initiated, but is expected to dry beyond the -2 bar limit of the wet range polynomial. The dry range polynomial is used, so a multiplier of 0.1 is entered in the bridge transform instruction.

When the water potential is computed it is written over the resistance value. The potentials are stored in Input locations 1-12 where they may be accessed for output to Final Storage. If it was desired to retain the resistance values the potential measurements could be stored in locations 13-24 by changing parameter 3 in Instruction 55 to 13.

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

FIGURE 7.16-1. 12 Gypsum Blocks

Connected to the CR7

The first 6 blocks are excited by excitation channel 1 and the last 6 by channel 2. Thus, 6 is entered for the number of measurements per excitation channel in Parameter 7 of Instruction

PROGRAM

01: P5 AC Half Bridge

01: 12 Reps 02: 16 500 mV fast Range 03: 1 IN Card 04: 1 IN Chan 05: 1 EX Card 06: 6 EX Chan 07: 6 Meas/EX 08: 500 mV Excitation 09: 1 Loc [:POTEN #1 ] 10: 1 Mult 11: 0 Offset

02: P59 BR Transform Rf[X/(1-X)]

01: 12 Reps 02: 1 Loc [:POTEN #1 ] 03: .1 Multiplier (Rf)

03: P55 Polynomial

01: 12 Reps 02: 1 X Loc POTEN #1 03: 1 F(X) Loc [:POTEN #1 ] 04: .15836 C0 05: 6.1445 C1 06: -8.4139 C2 07: 9.2493 C3 08: -3.1685 C4 09: .33392 C5

7-13

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES

7.17 NONLINEAR THERMISTOR IN HALF BRIDGE (CAMPBELL SCIENTIFIC MODEL 101)

Instruction 11, 107 Thermistor Probe, automatically linearizes the output of the nonlinear thermistor in the 107 Probe by transforming the millivolt reading with a 5th order polynomial. Instruction 55, Polynomial, can be used to linearize the output of any nonlinear thermistor, provided the correlation between temperature and probe output is known, and an appropriate polynomial fit has been determined. In this example, the CR7 is used to measure the temperature of 5 Campbell Scientific 101 Probes (used with the CR21). Instruction 4, Excite, Delay and Measure, is used because the high source resistance of the probe requires a long input settling time (See Section 13.3.1). The excitation voltage is 2000 mV, the same as used in the CR21. The signal voltage is then transformed to temperature using the Polynomial Instruction.

The manual for the 101 Probe gives the coefficients of the 5th order polynomial used to convert the output in millivolts to temperature (E denotes the power of 10 by which the mantissa is multiplied):

C0 -53.7842 C1 0.147974 C2 -2.18755E-4 C3 2.19046E-7 C4 -1.11341E-10 C5 2.33651E-14

The CR7 will only allow 5 significant digits to the right or left of the decimal point to be entered from the key board. The polynomial can not be applied exactly as given in the 101 manual. The initial millivolt reading must be scaled if the coefficients of the higher order terms are to be entered with the maximum number of significant digits. If 0.001 is used as a multiplier on the millivolt output, the coefficients are divided by

0.001 raised to the appropriate power, (i.e., C0=C0, C1=C1/0.001, C2=C2/.000001 etc.). With this adjustment, the coefficients entered in Parameters 4-9 of Instruction 55 become:

FIGURE 7.17-1. 101 Thermistor Probes

Connected to CR7

PROGRAM

01: P4 Excite,Delay,Volt(SE)

01: 5 Reps 02: 8 5000 mV slow Range 03: 1 IN Card 04: 1 IN Chan 05: 1 EX Card 06: 1 EX Chan 07: 5 Meas/EX 08: 10 Delay (units .01sec) 09: 2000 mV Excitation 10: 1 Loc [:101 T #1 ] 11: 0.001 Mult 12: 0 Offset

02: P55 Polynomial

01: 5 Reps 02: 1 X Loc 101 T #1 03: 1 F(X) Loc [:101 T #1 ] 04: -53.784 C0 05: 147.97 C1 06: -218.76 C2 07: 219.05 C3 08: -111.34 C4 09: 23.365 C5

7-14

C0 -53.784 C1 147.97 C2 -218.76 C3 219.05 C4 -111.34 C5 23.365

SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES

The following examples are intended to illustrate the use of Processing and Program Control Instructions, flags, and the capability to direct the results of Output Processing Instructions to Input Storage.

The specific examples may not be as important as some of the techniques employed, for example:

Directing Output Processing to Input Storage is used in the Running Average and Rainfall Intensity examples (8.1 and 8.2).

Flags tests are used in the Running Average, Interrupt Subroutine, and Converting Wind Direction examples (8.1, 8.4, and 8.6)

These examples are not complete programs to be taken verbatim. They need to be altered to fit specific needs.

8.1 COMPUTATION OF RUNNING AVERAGE

It is sometimes necessary to compute a running average (i.e., the average includes a fixed number of samples and is continuously updated as new samples are taken). Because the output interval is shorter than the averaging period, Instruction 71 cannot be used; the algorithm for computing this average must be programmed by the user. The following example demonstrates a program for computing a running average.

In this example, each time a new measurement is made (in this case a thermocouple temperature) an average is computed for the 10 most recent samples. This is done by saving all 10 temperatures in contiguous input locations and using the Spatial Average Instruction (51) to compute the average. The temperatures are stored in locations 11 through 20. Each time the table is executed, the new measurement is stored in location 20 and the average is stored in location 2. The Block Move Instruction (54) is then used to move the temperatures from locations 12 through 20 down by one location; the oldest measurement (in location 11) is lost when the temperature from location 12 is written over it.

Input Location Labels: 1:Panl Temp 15:Temp i-5

2:10smpl av 16:Temp i-4 11:Temp i-9 17:Temp i-3 12:Temp i-8 18:Temp i-2 13:Temp i-7 19:Temp i-1 14:Temp i-6 20:Temp i

Where i is current reading, i-1 is previous reading, etc.

* 1 Table 1 Programs

01: 1 Sec. Execution Interval

01: P17 Panel Temperature

01: 1 IN Card 02: 1 Loc [:Panl Temp]

02: P14 Thermocouple Temp (DIFF)

01: 1 Rep 02: 1 1500 uV slow Range 03: 1 IN Card 04: 1 IN Chan 05: 1 Type T (Copper-Constantan) 06: 1 Ref Temp Loc Panl Temp 07: 20 Loc [:Temp i ] 08: 1 Mult 09: 0.0000 Offset

03: P51 Spatial Average

01: 10 Swath 02: 11 First Loc Temp i-9 03: 2 Avg Loc [:10smpl av]

8-1

SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES

04: P54 Block Move

01: 9 No. of Values 02: 12 First Source Loc Temp i-8 03: 1 Source Step 04: 11 First Destin. Loc [:Temp i-9 ] 05: 1 Destination Step

05: P86 Do

01: 10 Set high Flag 0 (output)

06: P70 Sample

01: 1 Rep

02: 2 Loc 10smpl av 07: P End Table 1 In the above example, all samples for the

average are stored in input locations. This is necessary when an average must be output with each new sample. In most cases, averages are desired less frequently than sampling. For example, it may be necessary to sample some parameter every five seconds and output every hour an average of the previous three hours' readings. If all samples were saved, this would require 2160 input locations. The same value can be obtained by computing an hourly average and averaging the hourly averages for the past three hours. To do this requires that hourly averages be stored in input locations.

Instruction 80 is used to send the one hour average to Input Storage and again to send the three hour average to Final Storage.

Input Location Labels: 1:AVG i-2

2:AVG i-1 3:AVG i 4:3 HR AVG 5:XX mg/M3

02: P92 If time is

01: 0 minutes into a 02: 60 minute interval 03: 10 Set high Flag 0 (output)

03: P80 Set Active Storage Area

01: 3 Input Storage Area 02: 3 Array ID or location

04: P71 Average

01: 1 Rep 02: 5 Loc

05: P51 Spatial Average

01: 3 Swath 02: 1 First Loc AVG i-2 03: 4 Avg Loc [:3 HR AVG ]

06: P80 Set Active Storage Area

01: 1 Final Storage Area 02: 25 Array ID or location

07: P77 Real Time

01: 220 Day,Hour-Minute

08: P70 Sample

01: 1 Rep 02: 4 Loc 3 HR AVG

09: P91 If Flag

01: 10 0 (output) is set 02: 30 Then Do

10: P54 Block Move

01: 2 No. of Values 02: 2 First Source Loc 03: 1 Source Step 04: 1 First Destination Loc [:AVG i-2 ]

05: 1 Destination Step 11: P95 End 12: P End Table 1

* 1 Table 1 Programs

01: 5 Sec. Execution Interval

01: P2 Volt (DIFF)

01: 1 Rep 02: 8 5000 mV slow Range 03: 1 IN Card 04: 3 IN Chan 05: 3 Loc [:XX mg/m3 ] 06: 10 Mult 07: 0 Offset

8-2

8.2 RAINFALL INTENSITY

In this example, the total rain for the last 15 minutes is output only if any rain has occurred. The program makes use of the capability to direct the output of Output Processing Instructions to Input Storage.

SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES

Every 15 minutes, the total rain is sent to Input Storage. If the total is greater than 0, output is redirected to Final Storage, the time is output, and the total is sampled.

Input Location Labels: 1:Rain (mm)

2:15min tot * 1 Table 1 Programs

01: 60 Sec. Execution Interval

01: P3 Pulse

01: 1 Rep 02: 3 IN Card 03: 1 Pulse Input Chan 04: 2 Switch closure 05: 1 Loc [:Rain (mm)] 06: .254 Mult 07: 0 Offset

02: P92 If time is

01: 0 minutes into a 02: 15 minute interval 03: 10 Set high Flag 0 (output)

03: P80 Set Active Storage Area

01: 3 Input Storage Area 02: 2 Array ID or location

04: P72 Totalize

01: 1 Rep 02: 1 Loc Rain (mm)

05: P89 If X<=>F

01: 2 X Loc 02: 3 >= 03: 0 F 04: 30 Then Do

06: P80 Set Active Storage Area

01: 1 Final Storage Area 02: 25 Array ID or location

07: P77 Real Time

01: 220 Day,Hour-Minute

08: P70 Sample

01: 1 Rep 02: 2 Loc

09: P95 End

8.3 SUB 1 MINUTE OUTPUT INTERVAL SYNCHED TO REAL TIME

Instruction 92 has one minute resolution. If processed output is required on an interval less than one minute, Instructions 18 and 89 can be used to set the Output Flag on a shorter interval.

Instruction 18 takes time (tenths of seconds into minute, minutes into day, or hours into year), performs a modulo divide by a user specified value and loads it into an input location.

When the modulo divisor divides evenly into the interval, one gets a counter in an input location that goes to 0 on a periodic interval. In this example, tenths of seconds into the minute is modulo divided by 300. The counter counts up to 295 then goes to 0 (i.e., every 30 seconds; tenths of seconds into minute has a resolution of 0.1 seconds).

Instruction 89 is used to set the Output Flag when the tenths of seconds counter is less than 5 (the execution interval, 0.5 seconds). With this short program, the Output Flag could be set when the seconds counter equaled 0. However, if Instruction 18 followed a series of instructions that took longer than 0.1 seconds to execute or was in Table 2, executed at the same interval as an extensive Table 1, the time at which Instruction 18 was executed might be

0.1 seconds or more beyond the modulo divisor. The value output would not equal 0. Setting the Output Flag when the seconds counter is less than the execution interval avoids this problem.

Using Instruction 18 keeps the output interval synchronized with real time. If a counter incremented within the program was used to determine when to set the Output Flag, output would depend on the number of times the table was executed. The actual time of output would depend on when the program was actually compiled and started running. If the table overran its execution interval (Section 1.1.1), the output interval would not be the count multiplied by the execution interval, but some longer interval.

In this example a temperature (type E thermocouple) is measured every 0.5 seconds and the average output every 30 seconds.

8-3

SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES

Input Location Assignments: 1:TEMP DEG C

10:30 SEC 0 * 1 Table 1 Programs

01: .5 Sec. Execution Interval

01: P18 Time

01: 0 Tenths of seconds into minute

(maximum 600) 02: 300 Mod/by 03: 10 Loc [:30 SEC 0 ]

02: P17 Panel Temperature

01: 1 IN Card 02: 1 Loc [:REF TEMP ]

03: P14 Thermocouple Temp (DIFF)

01: 1 Rep 02: 13 15 mV fast Range 03: 1 IN Card 04: 2 IN Chan 05: 2 Type E (Chromel-Constantan) 06: 1 Ref Temp Loc REF TEMP 07: 2 Loc [:TC TEMP ] 08: 1 Mult 09: 0 Offset

04: P 89 If X<=>F

01: 10 X Loc 30 SEC 0 02: 4 < 03: .5 F 04: 10 Set high Flag 0 (output)

outputs for strip charts. The output values in this example are wind speed and wind direction.

The following program measures the sensors every five seconds. The readings are moved to another two locations and scaled to a 0 to 1000 millivolt output for the strip chart. Wind direction is changed from a 0-360 degree input to output representing 0 to 540 degrees. This conversion is done in a subroutine which is described in the next example.

The example also includes instructions to output wind vector every hour.

Input Location Assignments: 01:WS

02:0-360 WD 03:0-540 WD 04:WS output 05:WD output

* 1 Table 1 Programs

01: 3 Sec. Execution Interval

01: P3 Pulse

01: 1 Rep 02: 5 IN Card 03: 1 Pulse Input Chan 04: 22 Switch closure; Output Hz. 05: 1 Loc [:WS ] 06: 1.789 Mult 07: 1 Offset

05: P 71 Average

01: 1 Rep 02: 2 Loc TC TEMP

06: P End Table 1

8.4 ANALOG OUTPUT TO STRIP CHART

This example illustrates the use of the Analog Output Instruction 21 to output 2 analog voltages to strip chart.

While of questionable value because of power requirements and strip chart reliability, some archaic regulations require strip chart backup on weather data. Instruction 21 may be used with the CR7 to provide two continuous analog

8-4

02: P4 Excite,Delay,Volt(SE)

01: 1 Rep 02: 16 500 mV fast Range 03: 2 IN Card 04: 1 IN Chan 05: 1 EX Card 06: 1 EX Chan 07: 1 Meas/EX 08: 2 Delay (units .01sec) 09: 1000 mV Excitation 10: 2 Loc [:0-360 WD ] 11: .72 Mult 12: 0 Offset

03: P86 Do

01: 1 Call Subroutine 1

SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES

04: P37 Z=X*F

01: 1 X Loc WS 02: 10 F 03: 4 Z Loc [:WS output]

05: P37 Z=X*F

01: 3 X Loc 0-540 WD 02: 1.8519 F 03: 5 Z Loc [:WD output]

06: P21 Analog Out

01: 1 EX Card 02: 1 CAO Chan 03: 4 mv Loc WS output

07: P21 Analog Out

01: 1 EX Card 02: 2 CAO Chan 03: 5 mv Loc WD output

08: P92 If time is

01: 0 minutes into a 02: 60 minute interval 03: 10 Set high Flag 0 (output)

09: P69 Wind Vector

01: 1 Rep 02: 180 Samples per sub-interval 03: 00 Polar Sensor/(S, D1, SD1) 04: 1 Wind Speed/East Loc WS 05: 2 Wind Dir./North Loc 0-360 WD

10: P End Table 1

8.5 CONVERTING 0-360 WIND DIRECTION OUTPUT TO 0-540 FOR STRIP CHART

If 0-360 degree wind direction is output to a strip chart, the discontinuity at 0/360 will cause the pen to jump back and forth full scale when the winds are varying from the north. In the days of strip charts this was solved with a 0-540 degree pot on the wind vane (direction changes from 540 to 180 and from 0 to 360 so the pen only jumps once when the wind is out of the north or south).

When faced with the necessity of strip chart output (see previous example), the following algorithm can be used to change a 0-360 degree input to 0-540. (If you have a 0-540 pot, it can be used with the 21X since the Wind Vector Instruction, 69, will work with this output.)

To change 0-360 degrees to the 0-540 degrees, 360 degrees must sometimes be added to the reading when it is in the range of 0 to 180. The following algorithm does this by assuming that if the previous reading was less than 270, the vane has shifted through 180 degrees and does not need to be altered. If the previous 0-540 reading was greater than 270, 360 degrees is added.

This example is written as a subroutine which is used by the previous example to output an analog voltage to a strip chart.

Input Location Labels: 1:WS

2:0-360 WD 3:0-540 WD 4:WS output 5:WD output

* 3 Table 3 Subroutines 01: P85 Beginning of Subroutine

01: 1 Subroutine Number

02: P89 If X<=>F

01: 3 X Loc 0-540 WD 02: 3 >= 03: 270 F 04: 30 Then Do

03: P86 Do

01: 11 Set high Flag 1 04: P94 Else 05: P86 Do

01: 21 Set low Flag 1 06: P95 End 07: P31 Z=X

01: 2 X Loc 0-360 WD

02: 3 Z Loc [:0-540 WD ] 08: P89 If X<=>F

01: 3 X Loc 0-540 WD

02: 4 <

03: 180 F

04: 30 Then Do

8-5

SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES

09: P91 If Flag

01: 11 1 is set 02: 30 Then Do

10: P34 Z=X+F

01: 3 X Loc 0-540 WD 02: 360 F

03: 3 Z Loc [:0-540 WD ] 11: P95 End 12: P95 End 13: P95 End 14: P End Table 3

8.6 COVARIANCE CORRELATION PROGRAMMING EXAMPLE

The example is a two level meteorological tower with five sensors at each level. The three components of the wind are measured using prop anemometers. Two thermocouples (TC) are used to measure ambient and wet-bulb temperatures and calculate water vapor pressure on-line. All sensors are scanned once per second (1 Hz) and a five minute averaging period with a 30 minute Output Interval is specified. The example optimizes the input measurement sequence for speed and shows

the instructions necessary to provide calibrated inputs, properly ordered to produce the desired outputs from the Covariance Correlation (CV/CR) Instruction. Table 8.7-1 groups the sensors according to measurement type and gives the CR7 multiplier and offset.

The props can all be measured as single-ended voltages, but the vertical wind prop calibration differs from the U and V prop calibration. The fastest input sequence is to measure both levels (6 props) with a single instruction using the U and V calibration and correct the W measurements with the Fixed Multiply, Instruction 37.

The type E thermocouples are measured on the most sensitive input range, 5mV,

accommodating a ±80

C range between the

measurement and CR7 reference junction. The

resolution is (.33µV/(60µV/

C. Measuring absolute temperature with TCs

C) or about 0.006

requires a reference junction temperature measurement. This is measured with Instruction 17.

The specified outputs determine the input order required by the CV/CR Instruction. Table 8.6-2 lists the desired outputs from the two levels along with the Input Storage locations for the processed results.

TABLE 8.6-1. Example Sensor Description and CR7 Multiplier and Offset

DESCRIPTION SYMBOL SENSOR CALIB MEAS TYPE MULT OFFSET

Horiz. Wind U prop 18m/s/V S.E.V. .018m/s/mV 0.0 Horiz. Wind V prop 18m/s/V S.E.V. .018 0.0 Vert. Wind W prop 22m/s/V S.E.V. .022 0.0 Air Temp. Ta TC - TC DIFF. 1.0 Wet-bulb Temp. Tw TC - TC DIFF. 1.0

C0.0

Vap. Pressure e derived - - - -

8-6

SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES

TABLE 8.6-2. Example Outputs and Input Storage Locations

LEVEL 1 OUTPUTS

MEANS LOC VARIANCES LOC

M(W1) 20 V(W1) 25 CV(W1,U1) 30 CR(W1,U1) 34 M(U1) 21 V(U1) 26 CV(W1,V1) 31 CR(W1,V1) 35 M(V1) 22 V(V1) 27 CV(W1,Tal) 32 M(Tal) 23 V(Tal) 28 CV(W1,e1) 33 M(e1) 24 V(e1) 29

LEVEL 2 OUTPUTS

MEANS LOC VARIANCES LOC

M(W2) 36 V(W2) 41 CV(W2,U2) 46 M(U2) 37 V(U2) 42 CV(W2,V2) 47 M(V2) 38 V(V2) 43 CV(W2,Ta2) 48 M(Ta2) 39 V(Ta2) 44 CV(W2,e2) 49 M(e2) 40 V(e2) 45 CV(U2,V2) 50

Table 8.6-3 lists the input channel configuration and Input Storage allocation for the measured values. After reading the new input samples, the Level 2 measurements are relocated using the Block Move Instruction 54, then Ta1 is relocated through a separate move and e1 is positioned by specifying the destination location in the Wet/Dry-Bulb Instruction. The CV/CR Instruction must be entered twice, once for each level.

In addition to ordering Level 1 and Level 2 in locations 1-5 and 11-15 respectively, two more

COVARIANCES LOC CORRELATIONS LOC

COVARIANCES LOC

CV(U2,Ta2) 51 CV(U2,e2) 52 CV(V2,Ta2) 53 CV(V2,e2) 54

locations are required. Converting the wet-/drybulb measurements to vapor pressure using Instruction 57 requires atmospheric pressure. We'll use the standard atmosphere for the site elevation and key the value into Location 17 using the C command in the *6 Mode. The reference junction temperature obtained by Instruction 17 is stored in Location 16.

This example requires that 54 locations be allotted to Input Storage and 79 to Intermediate Storage (35 for the 1st CV/CR Instruction, 43 for the second, and 1 for Instruction 92).

TABLE 8.6-3. Example Input Channel and Location Assignments

INPUT INPUT INPUT INPUT

PARAM CHAN LOC PARAM LOC PARA LOC W1 1 1 W1 1 W1 1

U1 2 2 U1 2 U1 2 V1 3 3 V1 3 V1 3 W2 4 4 Ta1 9 ----------------------- Ta1 4 U2 5 5 Tw1 10 Separate moves e1 5 V2 6 6 W2 11 W2 11 Ta2 7 7 ->Block-> U2 12 U2 12 Tw2 8 8 move V2 13 V2 13 Ta1 9 9 Ta2 14 Ta2 14 Tw1 10 10 Tw2 15 e2 15

8-7

SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES

* 1 Table 1 Programs

01: 1 Sec. Execution Interval

01: P17 Panel Temperature

01: 1 IN Card 02: 16 Loc [:PANL TEMP]

02: P1 Volt (SE)

01: 6 Reps 02: 8 5000 mV slow Range 03: 1 IN Card 04: 1 IN Chan 05: 1 Loc [:W1 ] 06: .018 Mult 07: 0 Offset

03: P14 Thermocouple Temp (DIFF)

01: 4 Reps 02: 15 150 mV fast Range 03: 1 IN Card 04: 7 IN Chan 05: 2 Type E (Chromel-Constantan) 06: 16 Ref Temp Loc PANL TEMP 07: 7 Loc [:Ta2 ] 08: 1 Mult 09: 0 Offset

04: P37 Z=X*F

01: 1 X Loc W1 02: 1.22 F 03: 1 Z Loc [:W1 ]

05: P37 Z=X*F

01: 4 X Loc W2 02: 1.22 F 03: 4 Z Loc [:W2 ]

06: P54 Block Move

01: 5 No. of Values 02: 4 First Source Loc W2 03: 1 Source Step 04: 11 First Destination Loc [:W2 ] 05: 1 Destination Step

07: P31 Z=X

01: 9 X Loc 02: 4 Z Loc [:W2 ]

09: P57 Wet/Dry Bulb Temp to VP

01: 17 Pressure Loc 02: 14 Dry Bulb Temp Loc 03: 15 Wet Bulb Temp Loc Tw2 04: 15 Loc [:Tw2 ]

10: P92 If time is

01: 0 minutes into a 02: 30 minute interval 03: 10 Set high Flag 0 (output)

11: P62 CV/CR

01: 5 No. of Input Values 02: 5 No. of Means 03: 5 No. of Variances 04: 0 No. of Std. Dev. 05: 4 No. of Covariances 06: 2 No. of Correlations 07: 300 Samples per Average 08: 1 First Sample Loc W1 09: 20 Loc [:MEAN (W1)]

12: P62 CV/CR

01: 5 No. of Input Values 02: 5 No. of Means 03: 5 No. of Variances 04: 0 No. of Std. Dev. 05: 4 No. of Covariances 06: 2 No. of Correlations 07: 300 Samples per Average 08: 11 First Sample Loc W2 09: 36 Loc [:MEAN (W2)]

13: P77 Real Time

01: 110 Day,Hour-Minute

14: P70 Sample

01: 35 Reps

02: 20 Loc MEAN (W1) 15: P End Table 1 * A Mode 10 Memory Allocation

01: 54 Input Locations

02: 79 Intermediate Locations

08: P57 Wet/Dry Bulb Temp to VP

01: 17 Pressure Loc 02: 9 Dry Bulb Temp Loc 03: 10 Wet Bulb Temp Loc 04: 5 Loc [:U2 ]

8-8

SECTION 9. INPUT/OUTPUT INSTRUCTIONS

TABLE 9-1. Input Voltage Ranges and Codes

Range Code Full Scale Range Resolution*

Slow Fast

16.67ms 250µs Integ. Integ. 1 11 ±1500 microvolts 50 nanovolts 2 12 ±5000 microvolts 166 nanovolts 3 13 ±15 millivolts 500 nanovolts 4 14 ±50 millivolts 1.66 microvolts 5 15 ±150 millivolts 5 microvolts 6 16 ±500 millivolts 16.6 microvolts 7 17 ±1500 millivolts 50 microvolts 8 18 ±5000 millivolts 166 microvolts

*Differential measurement, resolution for single-ended measurement is twice value shown.

When measuring voltages with the 723 Analog Input Card, the ±1500 µV and ±5000 µV ranges read out in microvolts, the rest of the ranges have the decimal point placed to display millivolts. The 726 50V Analog Input Card divides the input voltages by 10 before making the measurements, thus, to shift the decimal point so as to display millivolts a factor of ten must be used in the multiplier. Repetitions cannot be used to advance from one 726 card to the next.

When a voltage input exceeds the range programmed, the value which is stored is set to the maximum negative number displayed as -99999 in high resolution or 6999 in low resolution.

*** 1 SINGLE ENDED VOLTS ***

FUNCTION This instruction is used to measure voltage at a single ended input with respect to ground.

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Repetitions 02: 2 Range code (Table 9-1) 03: 2 Card number for first

measurement

04: 2 Single-ended channel

number for first measurement

05: 4 Input location number for first

measurement 06: FP Multiplier 07: FP Offset

Input locations altered: 1 per repetition

*** 2 DIFFERENTIAL VOLTS ***

FUNCTION This Instruction reads the voltage difference between the HI and LO inputs of a differential channel in the selected range from the selected card and channel(s) and places it in an input location(s). Table 9-1 lists the range codes. Both the high and low inputs must be within ±5V of the datalogger's ground (Common Mode Range Section 13.2). Pyranometers and thermopile sensors require a jumper between LO and Ground to keep them in Common Mode Range.

9-1

SECTION 9. INPUT/OUTPUT INSTRUCTIONS

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Repetitions 02: 2 Range code (Table 9-1) 03: 2 Card number for first

measurement

04: 2 Differential channel number

for first measurement

05: 4 Input location number for first

measurement 06: FP Multiplier 07: FP Offset

Input locations altered: 1 per repetition

*** 3 PULSE COUNT ***

INPUT RANGE - - - 32767 Counts per input interval

There are three input configurations which may be measured with the Pulse Count Instruction.

HIGH FREQUENCY PULSE In this configuration the minimum pulse width is 2 microseconds. The maximum input frequency is 250 kilohertz. The count is incremented when the input voltage changes from below 1.5 volts to above 3.5 volts. The maximum input voltage is ±20 volts.

LOW LEVEL AC This configuration is used for counting the frequency of AC signals from magnetic pulse flow transducers or other low voltage, sine wave inputs. The minimum input voltage is 6 mV RMS. Input hysteresis is 11 mV. The maximum AC input voltage is 20 volts RMS. The maximum input frequency ranges from 100Hz at 6mV RMS to 10,000Hz at 50mV or greater. Consult the factory if higher frequencies are desired.

SWITCH CLOSURE In this configuration the minimum switch closed time is 1 millisecond. The minimum switch open time is 4 milliseconds. The maximum bounce time is 1.4 milliseconds open without being counted.

All pulse counters in one I/O Module are reset at the same time. The reset time interval is equal to the execution interval of the program table in which the Pulse Count Instruction(s) occur. When programs are compiled, the CR7

will set the reset time interval to the execution interval of the first program table in which a Pulse Count Instruction occurs. The execution intervals of subsequent program tables containing Pulse Count Instructions will have no effect on the reset time interval. (The maximum input frequency is 250KHz. The maximum number that can be stored in an accumulation register is 65,535.)

When datalogger time is changed, whether through the keyboard or with a telecommunications program, a partial recompile is automatically done to resynchronize program execution with real time. The resynchronization process resets the pulse accumulation interval resulting in an interval whose length can be anywhere between one second too short to almost twice as long. Pulses are not lost during resynchronization so totalized values are correct but pulse rate information such as wind speed can be up to almost twice the correct value.

The options of discarding counts from long intervals and pulse input type are selected by the code entered for the 4th parameter (Table 9-2).

All Pulse count instructions for the same I/O module and output instructions for the pulse count data should be kept in the same program table, preferably Table 1. If the pulse count instruction is contained in a subroutine, that subroutine must be called from Table 2.

When the system is interrupted for a task of sufficient priority to allow the pulse counters to exceed the programmed reset time interval, the resulting larger count can either be discarded leaving the value in the input location unchanged from the previous value or it can be used. If pulse counts are being totalized, a missing count could be significant; the value from the erroneously long interval should be used. If the pulse count is being processed a way in which the resultant value is dependent upon the sampling interval, such as sample, average, maximum, or minimum, it should be discarded. The option of discarding counts from long intervals and the input configuration are determined by the 4th parameter according to the following table.

9-2

SECTION 9. INPUT/OUTPUT INSTRUCTIONS

TABLE 9-2. Pulse Count Configuration

Codes

Code Configuration 00 High frequency pulse, all pulses

counted 01 Low level AC, all pulses counted 02 Switch closure, all pulses counted

1X Long interval data discarded, where X

is configuration code 2X Long interval data discarded, frequency

(Hz) output

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Repetitions 02: 2 Card number for first

measurement

03: 2 Pulse channel number for

first measurement 04: 2 Configuration code (Table 9-2) 05: 4 Input location number for first

measurement 06: FP Multiplier 07: FP Offset

Input locations altered: 1 per repetition

*** 4 EXCITE, DELAY AND MEASURE **

09: FP Excitation voltage (millivolts) 10: 4 Input location number for first

measurement 11: FP Multiplier 12: FP Offset

Input locations altered: 1 per repetition

*** 5 AC HALF BRIDGE ***

FUNCTION This Instruction is used to apply an excitation voltage to a half bridge (Figure 13.5-1), make a single ended voltage measurement of the bridge output, reverse the excitation voltage, then repeat the measurement. The difference between the two measurements is used to calculate the resulting value which is the ratio of the measurement to the excitation voltage. When the 1500 or 5000 µV input range is selected, the value is returned as 1000 times the ratio. For all other input ranges the value is just the ratio.

The excitation "on time" for each polarity is exactly the same to ensure that ionic sensors do not polarize with repetitive measurements. The range should be selected to be a fast measurement (range 11-18) limiting the excitation on time to 800 microseconds at each polarity. A slow integration time should not be used with ionic sensors because of polarization error.

FUNCTION This Instruction is used to apply an excitation voltage, delay a specified time and then make a single ended voltage measurement.

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Repetitions 02: 2 Range code (Table 9-1) 03: 2 Analog card number for first

measurement

04: 2 Single-ended channel

number for first measurement

05: 2 Excitation card for first

measurement

06: 2 Excitation channel number

for first measurement

07: 2 Number of measurements

per excitation channel

08: 4 Delay (0.01 sec)

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Repetitions 02: 2 Range code (Table 9-1) 03: 2 Analog card number for first

measurement 04: 2 Single-ended channel

number for first

measurement 05: 2 Excitation card for first

measurement 06: 2 Excitation channel number

for first measurement 07: 2 Number of measurements

per excitation channel 08: 4 Excitation voltage (millivolts) 09: 4 Input location number for first

measurement 10: FP Multiplier 11: FP Offset

Input locations altered: 1 per repetition

9-3

SECTION 9. INPUT/OUTPUT INSTRUCTIONS

*** 6 FULL BRIDGE WITH SINGLE ***

DIFFERENTIAL MEASUREMENT

FUNCTION This Instruction is used to apply an excitation voltage to a full bridge (Figure 13.5-1), make a differential voltage measurement of the bridge output, reverse the excitation voltage, then repeat the measurement. The resulting value is 1000 times the ratio of the measurement to the excitation voltage.

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Repetitions (95 max) 02: 2 Range code (Table 9-1) 03: 2 Analog card number for first

measurement

04: 2 Differential channel number

for first measurement

05: 2 Excitation card for first

measurement

06: 2 Excitation channel number

for first measurement

07: 2 Number of measurements

per excitation channel 08: 4 Excitation voltage (millivolts) 09: 4 Input location number for first

measurement 10: FP Multiplier 11: FP Offset

Input locations altered: 1 per repetition

*** 7 THREE WIRE HALF BRIDGE ***

FUNCTION This Instruction is used to determine the ratio of the sensor resistance to a known resistance using a separate voltage sensing wire from the sensor to compensate for lead wire resistance.

The measurement sequence is to apply an excitation voltage, make two voltage measurements on two adjacent single ended channels, the first on the reference resistor and the second on the voltage sensing wire from the sensor (Figure 13.5-1), then reverse the excitation voltage and repeat the measurements. The two measurements are used to calculate the resulting value which is the ratio of the voltage across the sensor to the voltage across the reference resistor.

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Repetitions (95 max) 02: 2 Range code for both

measurements (Table 9-1)

03: 2 Analog card number for first

measurement

04: 2 Single-ended channel number

for first measurement

05: 2 Excitation card for first

measurement

06: 2 Excitation channel number

for first measurement

07: 2 Number of measurements

per excitation channel 08: 4 Excitation voltage (millivolts) 09: 4 Input location number for first

measurement 10: FP Multiplier 11: FP Offset

Input locations altered: 1 per repetition

*** 9 FULL BRIDGE WITH EXCITATION ***

COMPENSATION

FUNCTION This Instruction is used to apply an excitation voltage and make two differential voltage measurements, then reverse the polarity of the excitation and repeat the measurements. The measurements are made on sequential channels. The result is the voltage measured on the second channel (V2) divided by the voltage measured on the first (V1). If V1 is measured on the 5V range (code 8 or 18 in Parameter 2), then the result is 1000 times V2/V1. A 1 before the excitation channel number (1X) causes the excitation channel to be incremented with each repetition.

When used as a 6 wire full bridge (Figure 13.5-

1), the connections are made so that V1 is the measurement of the voltage drop across the full bridge, and V2 is the measurement of the bridge output. Because the excitation voltage for a full bridge measurement is usually in the 5V range, the output is usually 1000 V2/V1 or millivolts output per volt excitation. When used to measure a 4 wire half bridge, the connections are made so that V1 is the voltage drop across the fixed resistor (Rf), and V2 is the drop across the sensor (Rs). As long as V1 is not measured on the 5V range, the result is V2/V1 which equals Rs/Rf.

9-4

SECTION 9. INPUT/OUTPUT INSTRUCTIONS

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Repetitions (47 max) 02: 2 Excitation range code (Table

9-1)

03: 2 Bridge range code for (Table

9-1)

04: 2 Analog card number for first

measurement

05: 2 Differential channel number

for first measurement

06: 2 Excitation card for first

measurement

07: 2 Excitation channel number

for first measurement

08: 2 Number of measurements

per excitation channel 09: 4 Excitation voltage (millivolts) 10: 4 Input location number for first

measurement 11: FP Multiplier 12: FP Offset

Input locations altered: 1 per repetition

*** 10 BATTERY VOLTAGE ***

FUNCTION This instruction reads the battery voltage from the currently active I/O module and writes it to an input location. The units for battery voltage are volts.

PAR. DATA NO. TYPE DESCRIPTION

Curve Fit Error --

Range (oC) Error (

-40 to +55 ±1.0

-35 to +48 ±0.1 This instruction uses a single excitation channel

since several hundred probes can be driven by a single excitation output. For this reason, Instruction 11 does not require a "measurement/excitation" parameter.

A multiplier of 1 and an offset of 0 yields temperature in degrees C.

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Repetitions 02: 2 Analog card number for first

03: 2 Single-ended channel

04: 2 Excitation card number for 05: 2 Excitation channel number 06: 4 Input location of first 07: FP Multiplier

08: FP Offset Input locations altered: 1 per repetition

*** 12 207 RELATIVE HUMIDITY PROBE ***

measurement number for first

measurement first measurement for first measurement measurement

01: 4 Input location number Input locations altered: 1

*** 11 107 THERMISTOR PROBE ***

FUNCTION This instruction applies a 4 VAC excitation voltage to Campbell Scientific's Model 107 Thermistor Probe, makes a fast, single ended voltage measurement on the 15 mV range across a resistor in series with the thermistor and calculates the temperature in oC with a polynomial. The maximum polynomial error from -40 oC to +55 oC is given below:

FUNCTION This instruction applies a 3 VAC excitation across Campbell Scientific's Model 207 Temperature and RH Probe, makes a fast single ended measurement across a series resistor on the 150 mV range, linearizes the result with a 5th order polynomial and performs the required temperature compensation before outputting the result in % RH.

When measuring several probes, all the RH elements should be connected sequentially. Any temperature elements used for compensating the respective RH value should also be sequentially connected to make use of the REP feature in Instruction 11.

9-5

SECTION 9. INPUT/OUTPUT INSTRUCTIONS

The temperature value used in compensating the RH value (Parameter 7) must be obtained (see Instruction 11) prior to executing Instruction 12.

The RH results are placed sequentially into the input locations beginning with the first RH value. In some situations the RH sensors might be deployed such that only small temperature variations exist within a given set of probes. In these cases a single temperature may be used to compensate the subset of RH measurements instead of making a temperature measurement for each RH probe. If the complete set of temperature values are not needed, this approach uses less input channels. Parameter 6 is used to specify how many consecutive RH values get compensated per temperature measurement.

In the 207 probe, the RH and temperature elements use a common excitation line. Since a single excitation channel can drive several hundred probes, there is no "measurements/excitation" parameter in Instruction 12. NEVER EXCITE THE 207 PROBE WITH DC EXCITATION as the RH chip will be damaged.

The maximum RH polynomial error is given below:

Curve Fit Error --

07: 4 Input location for first

compensating temperature measurement

08: 4 Input location for first

measurement 09: FP Multiplier 10: FP Offset

Input locations altered: 1 per repetition

*** 13 THERMOCOUPLE ***

TEMPERATURE, SINGLE ENDED

FUNCTION This Instruction uses the selected thermocouple calibration to calculate the thermocouple output voltage at the reference temperature, then it makes a SINGLE ENDED VOLTAGE MEASUREMENT (Section 13.2) on the thermocouple and adds the measured voltage to the calculated reference voltage, then converts the voltage to temperature in oC (Section 13.4).

Table 9-3 gives the thermocouple type codes. The reference temperature location will be incremented by one each repetition if C is keyed before entering Parameter 6. When this option is exercised, two minus signs (--) will appear as the right most characters of the display.

A multiplier of 1 and an offset of 0 yields temperature in degrees C.

Range (%RH) Error (%RH) 10 - 100 ±4 15 - 94 ±1

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Repetitions 02: 2 Analog card number for first

measurement

03: 2 Single-ended channel for first

measurement

04: 2 Excitation card number for

first measurement

05: 2 Excitation channel number

for first measurement

06: 2 Number of R.H.

measurements per compensating temperature measurement

9-6

TABLE 9-3. Thermocouple Type Codes

Code Thermocouple Type

1 T (copper - constantan) 2 E (chromel - constantan) 3 K (chromel - alumel) 4 J (iron - constantan) 5 B (platinum - rhodium) 6 R (platinum - rhodium) 7 S (platinum - rhodium) 1X Output temperature difference between

Reference and Thermocouple 2X Skip every other single ended channel 8X TC input from A5B40 Isolation Amplifier

(use 5 V range)

SECTION 9. INPUT/OUTPUT INSTRUCTIONS

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Repetitions 02: 2 Range code (Table 9-1) 03: 2 Analog card number 04: 2 Single-ended channel number

for first measurement 05: 2 TC type code (Table 9-3) 06: 4 Reference temperature

location. (When indexed (--)

this is incremented with each

rep.) 07: 4 Input location number 08: FP Multiplier 09: FP Offset

Input locations altered: 1 per repetition

*** 14 THERMOCOUPLE ***

TEMPERATURE, DIFFERENTIAL

MEASUREMENT

FUNCTION This instruction calculates the thermocouple temperature for the thermocouple type selected. The instruction specifies a DIFFERENTIAL VOLTAGE MEASUREMENT (Section 13.2) on the thermocouple, adds the measured voltage to the voltage calculated for the reference temperature relative to 0 oC, and converts the combined voltage to temperature in oC. The differential inputs are briefly shorted to ground prior to making the voltage measurement to insure that they are within the common mode range. (Section 13.4)

Table 9-3 gives the thermocouple type codes for Parameter 5, the option of skipping every other channel applies only to Instruction 13. The reference temperature location will be incremented by one each repetition if C is keyed before entering Parameter 6. When this option is exercised, two minus signs (--) will appear as the right most characters of the display.

A multiplier of 1 and an offset of 0 yields temperature in degrees C.

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Repetitions 02: 2 Range code (Table 9-1) 03: 2 Card number 04: 2 Beginning channel 05: 2 TC type code (Table 9-3)

06: 4 Reference temperature

location. (When indexed (--) this is incremented with each

rep.) 07: 4 Input location number 08: FP Multiplier 09: FP Offset

Input locations altered: 1 per repetition

*** 16 TEMPERATURE FROM ***

PLATINUM R.T.D.

FUNCTION This instruction uses the result of a previous RTD bridge measurement to calculate the temperature according to the DIN 43760 specification adjusted (1980) to the pending International Electrotechnical Commission standard. The range of linearization is -200 oC to 850 oC. The error in the linearization is less than 0.001 oC between -200 and +300 oC, and is less than 0.003 oC between -180 and +830 oC. The error (T calculated - T standard) is +0.006o at -200o and -0.006 at +850 oC. The input must be the ratio R/R0, where R is the RTD resistance and R0 the resistance of the RTD at 0 oC.

A multiplier of 1 and an offset of 0 yields temperature in degrees C.

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Repetitions 02: 4 Input location number of

(R/Ro) 03: 4 Input location number of

result 04: FP Multiplier 05: FP Offset

Input locations altered: 1 per repetition

*** 17 TEMPERATURE OF INPUT PANEL ***

FUNCTION This instruction measures the temperature in

C of the specified analog input card with RTD

(Model 723-T). PAR. DATA

NO. TYPE DESCRIPTION 01: 2 Analog card number

02: 4 Input location number Input locations altered: 1

9-7

SECTION 9. INPUT/OUTPUT INSTRUCTIONS

*** 18 MOVE TIME TO INPUT LOCATION ***

FUNCTION This instruction takes the current time in tenths of seconds into the minute, minutes into the day, or hours into the year and does a modulo divide (see Instruction 46) on the time value with the number specified in the second parameter. The result is stored in the specified input location. Entering 0 or a number which is greater than the maximum value of the time for the modulo divide will result in the actual time value being stored.

PARAMETER 1 OPTION CODES

CODE TIME UNITS

0 Tenths of seconds into minute

(maximum 600)

1 Minutes into current day (maximum

1440)

2 Hours into current year (maximum

8784)

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Option Code (see above) 02: 4 Number to modulo divide by 03: 4 Input location number

Input locations altered: 1

*** 19 MOVE SIGNATURE INTO ***

INPUT LOCATION

FUNCTION This instruction stores the signature of the Read Only Memory (ROM) and user program memory (RAM) into an input location. This signature is not the same as the signatures given in the *B mode. Recording the signature allows detection of any program change or ROM failure.

PAR. DATA NO. TYPE DESCRIPTION

*** 20 PORT SET ***

FUNCTION This instruction sets a specified Digital Control output port or is used to set the active excitation card for port commands with Program Control Instructions or manual toggling (Section 1.3.3). Ports may be set as specified by a flag or unconditionally.

PARAMETER 1 OPTION CODES

Code Function

00 Set port low 01 Set port high 1X Set port according to flag X 2X Set opposite to flag X 30 Set active port card

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Option code (see above) 02: 2 Excitation card number 03: 2 Port number (1-8)

Input locations altered: 0

*** 21 ANALOG OUTPUT ***

FUNCTION This instruction sets the continuous Analog Output (CAO) to a voltage level specified in an input location. The analog output degrades approximately 0.17mV every seven seconds requiring the instruction to be periodically repeated to maintain a given output accuracy.

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Excitation card number 02: 2 CAO channel number 03: 4 Input location number

containing analog output

magnitude in millivolts 01: 4 Input location number Input locations altered: 1

9-8

Input locations altered: 0 Input locations read: 1

SECTION 9. INPUT/OUTPUT INSTRUCTIONS

*** 22 EXCITATION WITH DELAY ***

FUNCTION This instruction is used in conjunction with others for measuring a response to a timed excitation using the switched analog outputs. It sets the selected excitation output to a specific value, waits for a specified time, turns off the excitation and waits an additional specified time before continuing execution of the following instruction. The excitation on time can be set to zero and the off time delay can be used if the only requirement is the delay of Program execution.

This instruction cannot be interrupted by Program Table 1 in order to make a measurement. This means that if it resides in Table 2 or Table 3 then Table 1 may be delayed.

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Excitation card number 02: 2 Excitation channel number 03: 4 Delay that excitation is on

(0.01 sec)

04: 4 Delay time after excitation is

turned off (0.01 sec)

05: FP Excitation voltage (millivolts)

*** 26 TIMER ***

FUNCTION This instruction will reset a timer or store the elapsed time registered by the timer in an Input Storage location. Instruction 26 can be used with Program Control Instructions to measure the elapsed time between specific input conditions. There is only one timer and it is common to all tables (e.g., if the timer is reset in Table 1 and later in Table 2, a subsequent instruction in Table 1 to read the timer will store the elapsed time since the timer was reset in Table 2).

Elapsed time is tracked in 0.1 second increments but displayed as an integer. For example, a 20 second elapsed time is displayed as "200".

The timer is also reset in response to certain keyboard entries:

1. When tables are changed and compiled with the *0 Mode, the timer is reset automatically.

2. When tables are changed and then compiled in the *B Mode, the timer is automatically reset and Tables 1 and 2 are disabled. Entering "*0" at this point enables both tables and resets the timer.

Input locations altered: 0

*** 23 SELECT I/O MODULE ***

FUNCTION This instruction is used when more than one I/O Module is under control and is used to specify which I/O Module subsequent instructions refer to. The I/O Module to which Instructions are addressed defaults to #1 at the start of each program table.

PAR. DATA NO. TYPE DESCRIPTION

01: 2 Module number (1,2,3 or 4) Input locations altered: 0

3. Entering "*6" after changing the tables compiles the programs, but does NOT reset the timer.

PAR. DATA NO. TYPE DESCRIPTION

01: 4 Input location number (enter

0 to reset)

Input locations altered: 1 (0 if timer is being

reset)

*** 101 SDM-INT8 ***

The 8 channel Interval Timer (INT8) is a measurement module which provides processed timing information to the datalogger. Each of the 8 input channels may be independently configured to detect either rising or falling edges of either high level or a low level signal. Each channel may be independently programmed. See the SDM-INT8 manual for detailed

9-9

SECTION 9. INPUT/OUTPUT INSTRUCTIONS

instructions and examples. This instruction is not in all PROM options.

PARAM. DATA NUMBER TYPE DESCRIPTION

01: 2 SDM address (base

4:00..33)

02: 4 *Input configuration;

channels 8,7,6,5

03: 4 *Input configuration;

channels 4,3,2,1 04: 4 **Function; channels 8,7,6,5 05: 4 **Function; channels 4,3,2,1 06: 4 ***Output option 07: 4 Starting input location

number 08: FP Mult 09: FP Offset

* Input configurations:

0 = high level, rising edge 1 = high level, falling edge 2 = low level, rising edge 3 = low level, falling edge

** Functions:

0 = no value returned 1 = period in ms 2 = frequency in kHz 3 = time since previous channel's edge

in ms 4 = time since channel 1 in ms 5 = counts on channel 2 since channel

1, linear interpolation 6 = frequency in kHz (low resolution) 7 = counts 8 = counts on Channel 2 since Channel

1, no interpolation

*** 102 SDM-SW8A ***

The 8 channel SDM-SW8A Switch Closure Input Module is a peripheral for measuring up to 8 channels of switch closure or voltage pulse inputs. Each channel may be configured to read single-pole double-throw (SPDT) switch closure, or single-pole single-throw (SPST) switch closure, or voltage pulse. Output options include counts, duty cycle, and state. This instruction is not in all PROM options.

The SW8A is addressed by the datalogger, allowing multiple SW8A's to be connected to one datalogger. 16 addresses are available.

If more channels are requested than exist in one module, the datalogger automatically increments the address and continues to the next SW8A. The address settings for multiple SW8A's must sequentially increase. For example, assume 2 SW8A's addressed as 22 and 23 are connected, and 12 Reps are requested. 8 channels from the first SW8A and the first 4 channels from the next will be read.

Only one Function Option (Parameter 3) may be specified per Instruction 102. If all 4 functions are desired, the instruction must be entered 4 times.

Function Option 0 provides the state of the signal at the time P102 is executed. A 1 or 0 corresponds to high or low states, respectively.

Function Option 1 provides signal duty cycle. The result is the percentage of time the signal is high during the sample interval.

*** Output option:

0 Average over execution interval 0-- Continuous averaging XXXX Averaging interval in msec,

XXXX>0

XXXX-- Capture all events until

XXXX edges of channel 1 (0<XXXX,9999)

9999-- Test memory

Input locations altered: 1 per function

9-10

Function Option 2 provides a count of the number of positive transitions of the signal.

Function Option 3 provides the signature of the SW8A PROM. A positive number (signature) indicates the PROM and RAM are good, a zero (0) indicates bad PROM, and a negative number indicates bad RAM. Function Option 3 is not used routinely, but is helpful in "debugging". Only one Rep is required for Option 3.

Parameter 4 specifies the first SW8A channel to be read (1..8). One or more sequential channels are read depending on the Reps. To optimize program efficiency, the sensors should be wired sequentially.

Campbell Scientific CR7 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

WARRANTY AND ASSISTANCE

OVERVIEW

PROGRAMMING

DATA RETRIEVAL/COMMUNICATION

PROGRAMMING EXAMPLES

INSTRUCTIONS

MEASUREMENTS

INSTALLATION

APPENDICES

SELECTED OPERATING DETAILS

CAUTIONARY NOTES

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW

OV1. PHYSICAL DESCRIPTION

OV1.1 700X CONTROL MODULE

OV1.2 720 I/O MODULE

OV2.1 INTERNAL MEMORY

OV2.2 CR7 INSTRUCTION TYPES

OV2.3.1 THE EXECUTION INTERVAL

OV2.3.2 THE OUTPUT INTERVAL

OV3. PROGRAMMING THE CR7

OV3.1 FUNCTIONAL MODES

OV3.3 PROGRAMMING SEQUENCE

OV3.2 KEY DEFINITION

OV3.4 INSTRUCTION FORMAT

OV3.5 ENTERING A PROGRAM

OV4. PROGRAMMING EXAMPLE

OV4.1 MEASUREMENT

OV4.2 OUTPUT

OV4.3 EDITING AN EXISTING PROGRAM

OV4.4 EDLOG PROGRAM LISTING

OV5. DATA RETRIEVAL OPTIONS

OV6. SPECIFICATIONS

SECTION 1. FUNCTIONAL MODES

1.1 PROGRAM TABLES - *1, *2, AND *3 MODES

1.1.1 EXECUTION INTERVAL

1.1.2 SUBROUTINES

1.1.3 TABLE PRIORITY/INTERRUPTS

1.1.4 COMPILING A PROGRAM

1.2 SETTING AND DISPLAYING THE CLOCK - *5 MODE

1.3 DISPLAYING AND ALTERING INPUT MEMORY OR FLAGS - *6 MODE

1.3.1 DISPLAYING AND ALTERING INPUT STORAGE

1.3.2 DISPLAYING AND TOGGLING USER FLAGS

1.3.3 DISPLAYING AND TOGGLING PORTS

1.5 MEMORY ALLOCATION - *A

1.5.1 INTERNAL MEMORY

1.5.2 *A MODE

1.6 MEMORY TESTING AND SYSTEM STATUS - *B

1.7 *C MODE -- SECURITY

1.8 *D MODE -- SAVE OR LOAD PROGRAM

1.8.1 TRANSFER TO COMPUTER/PRINTER

1.8.2 PROGRAM TRANSFER WITH STORAGE MODULE

SECTION 2. INTERNAL DATA STORAGE

2.1 FINAL STORAGE AREAS, OUTPUT ARRAYS, AND MEMORY POINTERS

2.2 DATA OUTPUT FORMAT AND RANGE LIMITS

2.2.1 RESOLUTION AND RANGE LIMITS

2.2.2 INPUT AND INTERMEDIATE STORAGE DATA FORMAT

2.3 DISPLAYING STORED DATA ON KEYBOARD/DISPLAY - *7 MODE

SECTION 3. INSTRUCTION SET BASICS

3.1 PARAMETER DATA TYPES

3.2 REPETITIONS/CARD NUMBER

3.3 ENTERING NEGATIVE NUMBERS

3.4 INDEXING INPUT LOCATIONS

3.5 VOLTAGE RANGE AND OVERRANGE DETECTION

3.6 OUTPUT PROCESSING

3.7 USE OF FLAGS: OUTPUT AND PROGRAM CONTROL

3.7.1 THE OUTPUT FLAG

3.7.2 THE INTERMEDIATE PROCESSING DISABLE FLAG

3.7.3 USER FLAGS

3.8 PROGRAM CONTROL LOGICAL CONSTRUCTIONS

3.8.1 IF THEN/ELSE COMPARISONS

3.8.2 END, INSTRUCTION 95

3.8.3 NESTING

3.9 INSTRUCTION MEMORY AND EXECUTION TIME

3.10 ERROR CODES

SECTION 4. EXTERNAL STORAGE PERIPHERALS

4.1.1 INSTRUCTION 96

1.1 PROGRAM TABLES - 1, 2, AND *3 MODES