Spectrum Controls 1746sc-NI8u User Manual

Owner’sGuide 0300172-03 Rev. D
SLC 500 A
NALOG INPUT
Thermocouple, RTD, Resistance, mV/V, mA
Catalog Numbers 1746sc-NI8u
U
NIVERSAL
ODULE
Important Notes
1. Please read all the information in this owner’s guide before installing the product.
2. The information in this owner's guide applies to hardware series B and firmware version 2.0 or later.
3. This guide assumes that the reader has a full working knowledge of the relevant processor.
Notice
The products and services described in this owner's guide are useful in a wide variety of applications. Therefore, the user and others responsible for applying the products and services described herein are responsible for determining their acceptability for each application. While efforts have been made to provide accurate information within this owner's guide, Spectrum Controls assumes no responsibility for the accuracy, completeness, or usefulness of the information herein.
Under no circumstances will Spectrum Controls be responsible or liable for any damages or losses, including indirect or consequential damages or losses, arising out of either the use of any information within this owner's guide or the use of any product or service referenced herein.
No patent liability is assumed by Spectrum Controls with respect to the use of any of the information, products, circuits, programming, or services referenced herein.
The information in this owner's guide is subject to change without notice.
Limited Warranty
Spectrum Controls warrants that its products are free from defects in material and workmanship under normal use and service, as described in Spectrum Controls literature covering this product, for a period of 1 year. The obligations of Spectrum Controls under this warranty are limited to replacing or repairing, at its option, at its factory or facility, any product which shall, in the applicable period after shipment, be returned to the Spectrum Controls facility, transportation charges prepaid, and which after examination is determined, to the satisfaction of Spectrum Controls, to be thus defective.
This warranty shall not apply to any such equipment which shall have been repaired or altered except by Spectrum Controls or which shall have been subject to misuse, neglect, or accident. In no case shall the liability of Spectrum Controls exceed the purchase price. The aforementioned provisions do not extend the original warranty period of any product which has either been repaired or replaced by Spectrum Controls.
Who Should Use This Guide
Preface
Read this preface to familiarize yourself with the rest of the owner’s guide. This preface covers:
• who should use this guide
• what this guide covers
• related Allen-Bradley documents
• terms & abbreviations you should know
Use this guide if you design, install, program, or maintain a control system that uses Allen-Bradley Small Logic Controllers.
You should have a basic understanding of SLC 500 products. You should also understand electronic process control and the ladder program instructions required to generate the electronic signals that control your application. If you do not, contact your local Allen-Bradley representative for the proper training before using these products.
What This Guide Covers
Related Allen­Bradley Documents
This guide covers the 1746sc-NI8u universal analog input module. It contains the information you need to install, wire, use, and maintain these modules. It also provides diagnostic and troubleshooting help should the need arise.
Table A lists several Allen-Bradley documents that may help you as you use these products.
ii SLC 500™ Universal Analog Input Modules
Table A. Related Allen-Bradley documents
Allen-Bradley Doc. No. Title
1747-2.30 SLC 500 System Overview
SGI-1.1 Application Considerations for Solid State Controls
1770-4.1 Allen-Bradley Programmable Controller Grounding and
1747-6.2 Installation & Operation Manual for Modular Hardware
1747-NI001 Installation & Operation Manual for Fixed Hardware Style
1747-6.4 Allen-Bradley Advanced Programming Software (APS)
1747-6.11 Allen-Bradley Advanced Programming Software (APS)
1747-6.3 Getting Started Guide for Advanced Programming
Wiring Guidelines
Style Programmable Controllers
Programmable Controllers
User Manual
Reference Manual
Software (APS)
Terms & Abbreviations You Should Know
ABT-1747-TSG001 SLC 500 Software Programmers’s Quick Reference Guide
1747-NP002 Allen-Bradley HHT (Hand-Held Terminal) User Manual
1747-NM009 Getting Started Guide for HHT (Hand-Held Terminal)
SD499 Allen-Bradley Publication Index
AG-7.1 Allen-Bradley Industrial Automation Glossary
To obtain a copy of any of the Allen-Bradley documents listed, contact your local Allen-Bradley office or distributor.
You should understand the following terms and abbreviations before using this guide.
A/D - Refers to analog-to-digital conversion. The conversion produces a digital value whose magnitude is proportional to the instantaneous magnitude of an analog input signal.
Attenuation – The reduction in magnitude of a signal as it passes through a system. The opposite of gain.
Channel – Refers to one of eight, small-signal analog input interfaces to the module’s terminal block. Each channel is configured for connection to a thermocouple or DC millivolt (mV) input device, and has its own configuration and status words.
Chassis – See rack.
Preface iii
CJC - (Cold Junction Compensation) The means by which the module compensates for the offset voltage error introduced by the temperature at the junction between the thermocouple lead wire and the input terminal block (the cold junction).
Common mode rejection ratio (CMRR) - The ratio of a device’s differential voltage gain to common mode voltage gain. Expressed in dB, CMRR is a comparative measure of a device’s ability to reject interference caused by a voltage common to its terminal relative to ground.
Common mode voltage – The voltage difference between the negative terminal and analog common during normal differential operation.
Configuration word – Contains the channel configuration information needed by the module to configure and operate each channel. Information is written to the configuration word through the logic supplied in your ladder program.
Cut-off frequency - The frequency at which the input signal is attenuated 3 dB by the digital filter. Frequency components of the input signal that are below the cut-off frequency are passed with under 3 dB of attenuation for low-pass filters.
dB (decibel) – A logarithmic measure of the ratio of two signal levels.
Data word – A 16-bit integer that represents the value of the analog input
channel. The channel data word is valid only when the channel is enabled and there are no channel errors.
Digital filter - A low-pass filter of the A/D converter. The digital filter provides high-frequency noise rejection.
Effective resolution – The number of bits in the channel data word that do not vary due to noise.
Full-scale error (gain error) – The difference in slope between the actual and ideal analog transfer functions.
Full-scale range (FSR) – The difference between the maximum and minimum specified analog values.
Gain drift – The change in full-scale transition voltage measured over the operating temperature range of the module.
Input data scaling - Depends on the data format that you select for the channel data work. You can select from scaled-for-PID or Engineering Units for millivolt, milliamp, thermocouple, RTD, or CJC inputs, which you must compute to fit your application’s temperature or voltage resolution.
iv SLC 500™ Universal Analog Input Modules
Local System - A control system with I/O chassis within several feet of the processor, and using 1746-C7 or 1746-C9 ribbon cable for communication.
LSB (least significant bit) – The bit that represents the smallest value within a string of bits. The “weight” of this value is defined as the full­scale range divided by the resolution.
Mulitplexer – A switching system that allows several input signals to share a common A/D converter.
Normal mode rejection (differential mode rejection) – A logarithmic measure, in dB, of a device’s ability to reject noise signals between or among circuit signal conductors, but not between the equipment grounding conductor or signal reference structure and the signal conductors.
Module update time – See channel update time.
Remote system - A control system shere the chassis can be located
several thousand feet from the processor chassis. Chassis communication is via the 1747-SN Scanner and 1747-ASB Remote I/O Adapter.
Resolution – The smallest detectable change in a measurement, typically expressed in engineering units (e.g. 0.15 °C) or as a number of bits. For example, a 12-bit system has 4096 possible output states. It can therefore measure 1 part in 4096. See also effective resolution.
RTD (Resistance Temperature Detector) - A temperature sensing element with 2, 3, 4, lead wires. It uses the basic characteristics that electrical resistance of metals increases with temperature. When a small current is applied to the RTD, it creates a voltage that varies with temperature. This voltage is processed and converted by the RTD module into a temperature value.
Sampling time - The time required by the A/D converter to sample an input channel.
Status word – Contains status information about the channel’s current configuration and operational state. You can use this information in your ladder program to determine whether the channel data word is valid.
Step response time – The time required for the A/D signal to reach 95% of its expected, final value, given a full-scale step change in the output data word.
Update time – The time for the module to sample and convert a channel input signal and make the resulting value available to the SLC processor.
Table of Contents
Preface
Who Should Use This Guide .................................................................................. i
What This Guide Covers ......................................................................................... i
Related Allen-Bradley Documents ......................................................................... i
Table A. Related Allen-Bradley documents.......................................................... ii
Terms & Abbreviations You Should Know ............................................................ ii
Module Overview
Installing And Wiring Your Module
Chapter 1
General Description................................................................................................ 1
System Overview .................................................................................................... 3
Compatibility with RTD and Resistance devices and cables............................. 6
Block Diagram ......................................................................................................... 7
Chapter 2
Electrostatic Damage ............................................................................................. 9
Power Requirements .............................................................................................. 9
Shunt Configuration .............................................................................................. 1 0
JP1, JP2, JP3, JP4, JP5, JP6, JP7, and JP8 Setup ........................................ 11
Current Input ......................................................................................................... 1 1
Non-Current Input ................................................................................................. 11
JP11 Setup ............................................................................................................ 1 1
JP9, JP10, and JP12 Setup.................................................................................12
Setting For RTD or Resistance Inputs ............................................................... 12
Setting For Non-RTD or Resistance Inputs ....................................................... 12
Selecting A Rack Slot ........................................................................................... 13
Module Installation and Removal ........................................................................ 1 3
Wiring Your Module ...............................................................................................15
Wiring RTD or Resistance Sensors to the NI8u Module..................................16
Preparing and Wiring the Cables ........................................................................ 18
Things To Consider Before Using Your Module
Chapter 3
Module ID Code .................................................................................................... 2 3
Module Addressing ............................................................................................... 2 3
Channel Filter Frequency Selection ................................................................... 2 5
Update Time .......................................................................................................... 29
Channel Turn-On, Turn-Off, and Reconfiguration Times .................................. 30
Auto-Calibration .................................................................................................... 3 0
Response to Slot Disabling ................................................................................. 32
vi SLC 500™ Universal Analog Input Modules
Channel Configuration, Data, and Status
Chapter 4
Channel Configuration ......................................................................................... 3 5
Channel Configuration Procedure ......................................................................36
Channel Data Word Resolution........................................................................... 42
Channel Data/Status Word .................................................................................. 45
Channel Status Checking .................................................................................... 4 5
Programming Examples
Chapter 5
Initial Programming............................................................................................... 51
Dynamic Programming ........................................................................................ 53
Verifying Channel Configuration Changes ......................................................... 54
Interfacing to the PID Instruction ........................................................................56
Monitoring Channel Status Bits ..........................................................................57
Testing Your Module
Maintaining Your Module And Ensuring Safety
Appendices
Chapter 6
Module and Channel Diagnostics .......................................................................63
LED Indicators ....................................................................................................... 6 4
Interpreting I/O Error Codes ................................................................................ 6 6
Verifying With Test Instrumentation..................................................................... 67
Chapter 7
Preventive Maintenance ....................................................................................... 69
Safety Considerations .......................................................................................... 6 9
Appendix A : Module Specifications
Electrical Specifications ....................................................................................... 7 3
Physical Specifications......................................................................................... 74
EnvironmentalSpecifications ............................................................................... 74
Input Specifications .............................................................................................. 7 4
Appendix B: Thermocouple Descriptions .......................................................... 9 1
J Type Thermocouples ......................................................................................... 9 1
K Type Thermocouples.........................................................................................93
T Type Thermocouples ......................................................................................... 95
E Type Thermocouples ......................................................................................... 9 7
R Type Thermocouples ........................................................................................ 99
S Type Thermocouples ...................................................................................... 10 0
B Type Thermocouples ...................................................................................... 102
N Type Thermocouples ..................................................................................... 1 03
References ......................................................................................................... 106
Preface vii
Appendix C: Using Grounded Junction, Ungrounded Junction, and Exposed Junction Thermocouples
Thermocouple Types ......................................................................................... 11 3
Isolation ............................................................................................................... 11 4
Getting Technical Assistance............................................................................ 117
Declaration of Conformity ................................................................................. 1 17
Figures
Figure 2.1 Module insertion into a rack ........................................................... 14
Figure 2.2 Terminal block diagram with CJC sensors ................................... 15
Figure 2.3 Ferrite EMI suppressor for CE compliance .................................. 2 0
Figure 2.4 Terminal block diagram with input cable ....................................... 2 0
Figure 3.1 Image table....................................................................................... 24
Figure 3.2 Signal attenuation with 10 Hz input filter ......................................27
Figure 3.3 Signal attenuation with 50 Hz input filter ......................................27
Figure 3.4 Signal attenuation with 60 Hz input filter ......................................28
Figure 3.5 Signal attenuation with 250 Hz input filter .................................... 2 8
Figure 5.1 Channel configuration ..................................................................... 51
Figure 5.2 Data table for initial programming.................................................. 52
Figure 5.3 Initial programming example .......................................................... 5 2
Figure 5.4 Dynamic programming example .................................................... 5 3
Figure 5.5 Data table for dynamic programming ............................................ 5 4
Figure 5.6 Programming for configuration changes example ....................... 55
Figure 5.7 Data table for configuration changes............................................. 55
Figure 5.8 Programming for PID Control Example ........................................ 56
Figure 5.9 Data table for PID Control .............................................................. 57
Figure 5.10 Monitoring channel status bits example ....................................... 5 8
Figure 5.11 Data table for monitoring channel status bits ............................... 5 8
Figure 6.1 Troubleshooting Flowchart .............................................................. 68
Tables
Table 1.1 Thermocouple Temperature Ranges .............................................. 1
Table 1.2 RTD Temperature Ranges ................................................................ 2
Table 1.3 Millivolt Input Ranges ........................................................................ 2
Table 1.4 Current Input Ranges........................................................................ 2
Table 1.5 Resistance Input Range ................................................................... 2
Table 1.6 Hardware Features............................................................................ 3
Table 1.7 Recommendations to minimize interference from radiated
electrical noise ................................................................................... 5
Table 1.8 Cable Specifications .......................................................................... 6
Table 2.1 Maximum current drawn by the module ........................................ 1 0
Table 3.1 Cut-off frequency, step response time, and effective resolution
(based on filter frequency).............................................................. 26
Table 3.2 Channel Sampling Time ................................................................. 29
viii SLC 500™ Universal Analog Input Modules
Table 4.1 Channel Configuration Word (O:e.3:0)..........................................36
Table 4.2 Channel Configuration Word (O:e.7:4)..........................................37
Table 4.3 1746sc-NI8u Universal Module -
Channel Data Word Format ........................................................... 41
Table 4.4 1746sc-NI8u Thermocouple Module -........................................... 42
Table 4.5 Channel 0-7 Status Word (I:e.0 through I:e.7) -
Bit Definitions ...................................................................................46
Table 6.1 Module-status LED .......................................................................... 6 4
Table 6.2 Module-status and Channel-status LED ....................................... 6 4
Chapter 1
Module Overview
This chapter describes the universal analog input module and explains how the SLC controller reads thermocouple or millivolt analog input data from the module. Read this chapter to familiarize yourself further with your universal analog input module. This chapter covers:
• general description and hardware features
• an overview of system and module operation
• block diagram of channel input circuits
General Description
This module is designed exclusively to mount into Allen-Bradley 1746 I/ O racks for use with Allen-Bradley SLC 500 fixed and modular systems. The module stores digitally converted thermocouple, RTD, millivolt (mV), volt (V), milliamp (mA), and CJC temperature analog data in its image table for retrieval by all fixed and modular SLC 500 processors. The module supports connections of up to eight channels of thermocouple, current or voltage inputs, OR four channels of RTD or resistance inputs and four channels of thermocouple, current or voltage inputs.
Input Ranges
The following tables provide compatibility information on the supported thermocouple types and their associated temperature ranges, the supported RTD types and their associated temperature ranges, as well as the millivolt, volt, milliamp and resistance input types supported by the NI8u module. To determine the practical temperature range of your thermocouple, refer to the specifications in appendices A and B. Detailed accuracy specifications for all input types can be found in appendix A.
Table 1.1 Thermocouple Temperature Ranges
Type °C Temperature Range °F Temperature Range
J -210°C to 760°C -346°F to 1400°F K -270°C to 1370°C -454°F to 2498°F T -270°C to 400°C -454°F to 752°F B 300°C to 1820°C 572°F to 3308°F E -270°C to 1000°C -454°F to 1832°F R 0°C to 1768°C 32°F to 3214°F S 0°C to 1768°C 32°F to 3214°F N 0°C to 1300°C 32°F to 2372°F C 0°C to 2315°C 32°F to 4199°F CJC Sensor -25°C to 105°C -13°F to 221°F
2 SLC 500™ Universal Analog Input Module
Table 1.2 RTD Temperature Ranges
Type °C Temperature Range °F Temperature Range
Platinum (385)1100 Ohm -200°C to +850°C -328°F to +1562°F
Platinum (3916)1100 Ohm -200°C to +630°C -328°F to +1166°F
Copper (426) 10 Ohm -100°C to +260°C -148°F to +500°F
Nickel (618) 120 Ohm -100°C to + 260°C -148°F to +500°F
Nickel (672) 120 Ohm -80°C to +260°C -112°F to + 500°F
200 Ohm -200°C to +750°C -328°F to +1382°F
500 Ohm -200°C to +850°C -328°F to +1562°F
1000 Ohm -200°C to +850°C -328°F to +1562°F
200 Ohm -200°C to +630°C -328°F to +1166°F
500 Ohm -200°C to +630°C -328°F to +1166°F
1000 Ohm -200°C to +630°C -328°F to +1166°F
1=The digits following the RTD type represent the temperature coefficient of resistance
(alpha, a), which is defined as the resistance change per Ohm per Platinum 385 refers to a platinum RTD with a = 0.00385 Ohms/Ohm - °°C, or simply
0.00385/°°C.
°
°
C. For instance,
Table 1.3 Millivolt Input Ranges
-50 to +50 mV
-100 to +100 mV
-500 to +500 mV
-2.0 to +2.0 V
0 to +5.0 V
1.0 to +5.0 V
0 to 10.0 V
-10.0 to +10.0 V
Table 1.4 Current Input Ranges
4 to 20 mA
0 to 20 mA
Table 1.5 Resistance Input Range
0 to 3000 Ohms
Chapter 1: Module Overview 3
All eight input channels are individually configurable for thermocouple, millivolt, volt, or milliamp input types. Channels 4 through 7 can be defined for RTD or resistance inputs, and then can be individually configured for a specific RTD or resistance type. Each input channel provides broken input, over-range, and under-range detection and indication, when enabled.
Hardware Features
The module fits into any single slot for I/O modules in either an SLC 500 modular system or an SLC 500 fixed system expansion chassis (1746-A2).
1
It is a Class 1
1
Requires use of Block Transfer in a remote configuration.
module (uses 8 input words and 8 output words).
The module utilizes two removable terminal blocks, that provides connections for the eight input channels. There are two cold-junction compensation (CJC) sensors that compensate for the cold junction at ambient temperature rather than at freezing (0°C). There are four current sources for supplying the RTD or resistance sensors. The module is configured through software, with jumpers used to define RTD, resistance, current or voltage input paths.
System Overview
Table 1.6 Hardware Features
Hardware Function
Channel Status LED Indicators Display operating and fault status of channels 0-7
Module Status LED Displays operating and fault status of the module
Side Label (Nameplate) Provides module information
Removable Terminal Block Provides electrical connection to input devices
Door Label Permits easy terminal identification
Self Locking Tabs Secure module in chassis slot
Diagnostic LEDs
The module contains diagnostic LEDs that help you identify the source of problems that may occur during power-up or during normal operation. Power-up and channel diagnostics are explained in Chapter 6, Testing Your Module.
The module communicates with the SLC 500 processor and receives +5 Vdc and +24 Vdc power from the system power supply through the parallel backplane interface. No external power supply is required. You may install as many universal modules in the system as the power supply can support.
4 SLC 500™ Universal Analog Input Module
The first four input channels (0 through 3) can receive input signals from thermocouples, millivolt, volt, or milliamp devices. The last four input channels (4 through 7) can receive input signals from thermocouples, millivolt, volt, milliamp, or 2, 3 or 4-wire RTD or resistance devices. If RTD or resistance inputs are selected, channels 4 through 7 can be individually configured for the supported RTD or resistance types.
When configured for thermocouple input types, the module converts analog input voltages into cold-junction compensated and linearized, digital temperature readings. The module uses the National Institute of Standards and Technology (NIST) linearization tables based on ITS-90 for thermocouple linearization.
When configured for RTD input types, the module converts the analog input voltages into digital temperature readings, based on the alpha type, wire type, and ohms specified. The standards used are the JIS C 1604­1997 for the Pt 385 RTD types, the JIS C 1604-1989 for the Pt 3916 RTD
types, SAMA RC21-4-1966 for the 10Cu 426 RTD, DIN 43760 Sept. 1987 for the 120 Ni 618 RTD, and MINCO Application Aid #18 May 1990 for the 120Ni 672 RTD.
When configured for millivolt, volt, milliamp, or resistance analog inputs, the module converts the analog values directly into digital counts. For those input types, the module assumes that the input signal is linear prior to input into the module.
System Operation
At power-up, the module checks its internal circuits, memory, and basic functions. During this time the module status LED remains off. If the module finds no faults, it turns on its module status LED.
After completing power-up checks, the module waits for valid channel configuration data from your SLC ladder logic program (channel status LEDs are off). After channel configuration data is transferred and channel enable bits are set for one or more channels, the module turns on its channel status LEDs. Then it continuously converts the inputs to the data format you selected for the channel.
Each time the module reads an input channel, the module tests that data for a fault, i.e. over-range, or under-range condition. If open-circuit detection is enabled, the module tests for an open circuit condition. If it detects an open-circuit, over-range, or under-range condition, the module sets a unique bit in the channel status word and causes the channel status LED to blink.
The SLC processor reads the converted thermocouple, RTD, resistance, millivolt, volt, or milliamp data from the module at the end of the program scan, or when commanded by the ladder program. After the processor and module determine that the data transfer was made without error, the data can be used in your ladder program.
Chapter 1: Module Overview 5
Module Operation
The module’s input circuitry consists of eight differential analog inputs, multiplexed into an A/D converter. The A/D converter reads the analog input signals and converts them to digital counts. The input circuitry also continuously samples the CJC sensors and compensates for temperature changes at the cold junction (terminal block). The module can be used with remote CJC sensor inputs. The sensors must be Analog Devices AD592CN temperature transducers. The module will not accept other CJC sensor inputs, and thermocouple inputs will not function properly if incorrect CJC sensors are used.
Module Addressing
The module requires eight words each in the SLC processor’s input and output image tables. Addresses for the module in slot e are as follows:
I:e.0-7 thermocouple/mV/V/mA, RTD, resistance or status
data for channels 0-7, respectively
O:e.0-7 configuration data for channels 0-7, respectively.
Compatibility with Thermocouple, Current, and Millivolt Devices & Cables
The module is compatible with the following standard types of thermocouples: B, E, J, K, N, R, S, T and C and extension wire. Refer to appendices B and C for details. The module is also compatible with a variety of voltage and current devices with an output of ±50, ±100 mV, +500mV, ±2V, 0-5V, 1-5V, 0-10V, ±10V, 0-20mA, and 4-20mA.
To minimize interference from radiated electrical noise, we recommend twisted-pair and highly shielded cables such as the following:
Table 1.7 Recommendations to minimize
interference from radiated electrical noise
For This Type of Device We Recommend This Cable (or equivalent)
Thermocouple Type J EIL Corp. J20-5-502
Thermocouple Type K EIL Corp. K20-5-510
Thermocouple Type T EIL Corp. T20-5-502
Other Thermocouple Types consult with EIL Corp or other manufacturers
mV, V, mA devices Belden 8761, shielded, twisted-pair
6 SLC 500™ Universal Analog Input Module
Compatibility with RTD and Resistance devices and cables
The module is compatible 100 Platinum 385, 200 Platinum 385, 55 Platinum 385, 1000 Platinum 385, 100 Platinum 3916, 200 Platinum 3916, 500 Platinum 3916, 1000 Platinum 3916, 10 Copper 426, 120 Nickel 618 and 120Ω Nickel 672 RTD types and 3000Ω resistance inputs,
and 3 possible wire types (2 wire, 3 wire, or 4 wire). Each RTD input individually supports four input pins on the terminal block: one excitation current source (EXC+), one excitation current drain (EXC-), one sense positive (CH+) and one sense negative (CH-). Only those pins are connected that are required by the selected RTD or resistance wire type. For 2, 3, or 4 wire configurations, the module can support a maximum combined cable length associated with an overall cable impedance of 25 ohms or less without exceeding its input limitations. The accuracy specifications provided herein do not include errors associated with unbalanced cable impedance.
Since the operating principle of the RTD and resistance inputs is based on the measurement of resistance, take special care in selecting your input cable. For 2-wire or 3-wire configuration, select a cable that has a consistent impedance throughout its entire length. For 2-wire configurations, we recommend that you use Belden #9501 (or
equivalent). For 3-wire configurations, we recommend that you use Belden #9533 (or equivalent) for short installation runs (less than 100
feet) or use Belden #83503 (or equivalent) for longer runs (greater than 100 feet) and in high humidity environments.
Table 1.8 Cable Specifications
Description Belden #9501 Belden#9533 Belden#83503
For 2-wire RTDs and For 3-wire RTDs and For 3-wire RTDs and
When used? potentiometers. potentiometers. Short potentiometers. Long
runs less than 100 feet runs greater than 100 and normal humidity feet or high humidity levels. levels.
Conductors 2, #24 AWG tinned 3, #24 AWG tinned 3, #24 AWG tinned
copper (7x32) copper (7x32) copper (7x32)
Shield Beldfoil aluminum Beldfoil aluminum Beldfoil aluminum
polyester shield polyester shield polyester shield w/ copper drain wire. w/copper drain wire. w/copper drain wire.
Insulation PVC S-R PVC Teflon
Jacket Chrome PVC Chrome PVC Red teflon
Agency NEC Type CM NEC Type CM NEC Art-800, Type CMP Approval
Temperature 80°C 80°C 200°C Rating
Chapter 1: Module Overview 7
Block Diagram
DC Voltage +
Analog Input -
Thermocouple
Input
0-20 mA +
Current Input -
RTD or
resistance
Input
RTD Sense +
Sense Return
CJCA +
Sensor -
CH2 +
CH2 -
SHIELD 2/3
CH 3 +
CH 3 -
EXC 6 +
CH6 +
CH6 -
EXC 6 -
Shield 6/7
EXC 7 +
CH 7 +
CH 7 -
EXC 7 -
CH 0 +
CH 0 -
SHIELD 0/1
CH 1+ CH 1 -
EXC 4 +
CH 4 +
CH 4 -
EXC 4 -
SHIELD 4/5
EXC 5 +
CH 5 +
CH 5 -
EXC 5 -
CJCB +
Sensor -
Vcc
Vcc
Vcc
Vcc
Multiplexers
Analog
to Digital
Converter
Digital
Filter
User Selected
Filter Frequency
Digital Value
8 SLC 500™ Universal Analog Input Module
Electrostatic Damage
Chapter 2
Installing And Wiring Your Module
Read this chapter to install and wire your module. This chapter covers:
• avoiding electrostatic damage
• determining power requirements
• installing the module
• wiring signal cables to the module’s terminal block
Electrostatic discharge can damage semiconductor devices inside this module if you touch backplane connector pins. Guard against electrostatic damage by observing the following precautions:
Power Requirements
CAUTION
!
The module receives its power through the SLC-500 chassis backplane from the fixed or modular +5 VDC and +24 VDC chassis power supply. The maximum current drawn by the module is shown in the table below.
ELECTROSTATICALLY SENSITIVE COMPONENTS
• Before handling the module, touch a grounded object to rid yourself of electrostatic charge.
• When handling the module, wear an approved wrist strap grounding device.
• Handle the module from the front, away from the backplane connector. Do not touch backplane connector pins.
• Keep the module in its static-shield container when not in use or during shipment.
Failure to observe these precautions can degrade the module’s performance or cause permanent damage.
10 SLC 500™ Universal Analog Input Module
Table 2.1. Maximum current drawn by the module
5VDC Amps 24VDC Amps
0.120 0.100
When using the module in a modular system, add the values shown above to the requirements of all other modules in the SLC to prevent overloading the chassis power supply.
When using the module in a fixed controller, be sure not to exceed the power supply rating for the 2-slot I/O chassis.
Considerations for a Modular System
Place your module in any slot of an SLC-500 modular, or modular expansion chassis, except for the left-most slot (slot 0) reserved for the SLC processor or adapter modules.
ShuntShunt
Shunt
ShuntShunt ConfigurationConfiguration
Configuration
ConfigurationConfiguration
Considerations for a Fixed Controller
The power supply in the 2-slot SLC 500 fixed I/O chassis (1746-A2) can support only specific combinations of modules. Make sure the chassis power supply can support the NI8u and additional module power requirements.
The 1746sc-NI8u module is a multi-purpose, multi-functional module, that is capable of supporting many different input types in a very small package. There are a few shunts on the board that allow the user to define input paths properly, which are imperative for the configuration control to allow proper utilization of the module. JP1 through JP8 supports the current input mode options of each of the inputs channels, 0 through 7, respectively. In order to define channels 4 through 7, JP9 and JP10, must be configured properly. JP11 is used at the factory and should not be modified. JP12 indicates whether or not RTD or resistance inputs are to be used in the configuration. The module is shipped with all current input shunts in place, and the remaining shunts installed for non-RTD or resistance inputs. The shunts are to be modified prior to installation of the module. Proper precautions for electrostatic handling should be followed. Small needlenose pliers may be used to configure the shunts, if needed.
AA
TTENTION:TTENTION:
A
TTENTION: Never touch the module without
AA
!
TTENTION:TTENTION: being properly strapped and connected to ground. Electrostatic damage may result.
Chapter 2: Installing And Wiring Your Module 11
JP11
The following diagram shows the module outline defining the placement of the various shunts, looking at the primary side of the board, with the terminal block pointing up. A brief description of each follows.
Terminal Block Header
JP1 JP2 JP3 JP4 JP5 JP6 JP7 JP8
JP9
JP10
JP11
JP12
JP1, JP2, JP3, JP4, JP5, JP6, JP7, and JP8 Setup
Current Input
Non-Current Input
JP11 Setup
There are eight shunts corresponding to eight inputs, respectively, that exist to support the 0 to 20mA or 4 to 20mA current input selections. JP1 corresponds to channel 0, and JP8 corresponds to channel 7. The shunts of JP2 through JP7 follow for channels 1 through 6, respectively. These shunts are two pin headers that only need to be connected if a channel is to be configured for current input. If the channel is to be used for any other type (thermocouple, millivolt, voltage for channels 0 through 3, or thermocouple, millivolt, voltage, RTD, or resistance for channels 4 through 7), then the pins are to be left open and unconnected.
Shunt in place
Shunt removed
Located in the bottom right hand corner, JP11 should always have pins 1 and 2 connected as shown. This shunt is used during manufacturing of the module, and should never be moved by the user.
12 SLC 500™ Universal Analog Input Module
JP9, JP10, and JP12 Setup
The NI8u module supports up to four RTD or resistance inputs on channels 4 through 7. In order to properly support RTD or resistance inputs, JP9, JP10, and JP12 have to be configured correctly. The function of JP9 and JP10 is to define the input path for the channels 4 through 7. JP9 and JP10 are four pin headers toward the right side of the board, looking at the primary side of the board with the terminal block pointing up. JP12 is a three pin header on the very bottom right hand corner, below JP11.
Setting For RTD or Resistance Inputs
The module will either support zero RTD or resistance inputs or four RTD or resistance inputs in channels 4 through 7. To properly configure JP9 and JP10 for RTD or resistance, set the shunts across pins 2 and 3 of the four pin headers. JP12 also needs to have pins 2 and 3 connected when RTD or resistance are to be used, as shown below.
Setting For Non-RTD or Resistance Inputs
JP9
JP10
JP12
If RTD and resistance inputs are not used, and channels 4 through 7 are to be defined as thermocouple inputs, current inputs, millivolt or voltage inputs, jumper pins 1 and 2 together, jumper pins 3 and 4 together, of JP9 and JP10, as defined below. JP12 also needs to have pins 1 and 2 connected when RTD and resistance inputs are not in use.
JP9
JP10
JP12
Selecting A Rack Slot
Chapter 2: Installing And Wiring Your Module 13
Two factors determine where you should install your module in the rack: ambient temperature and electrical noise. When selecting a slot for your module, try to position your module:
• in a rack close to the bottom of the enclosure (where the air is cooler)
• away from modules that generate significant heat, such as 32-point input/output modules
• in a slot away from ac or high-voltage dc modules, hard contact switches, relays, and ac motor drives
• away from the rack power supply (if using a modular system)
Remember that in a modular system, the processor always occupies the first slot of the rack.
Module Installation and Removal
When installing the module in a chassis, it is not necessary to remove the terminal blocks from the module. However, if the terminal blocks are removed, use the write-on label located on the side of the terminal blocks to identify the module location and type.
1746sc-
RACK_______SLOT_______
NI8u
1746sc-
RACK_______SLOT_______
NI8u
CAUTION
!
POSSIBLE EQUIPMENT OPERATION
Before installing or removing your module, always disconnect power from the SLC 500 system and from any other source to the module (in other words, don’t “hot swap” your module), and disconnect any devices wired to the module.
Failure to observe this precaution can cause unintended equipment operation and damage.
TB1
TB2
14 SLC 500™ Universal Analog Input Module
TB2
TB1
To insert your module into the rack, follow these steps:
1. Align the circuit board of your module with the card guides at the top and bottom of the chassis.
Figure 2.1. Module insertion into a rack
2. Slide your module into the chassis until both top and bottom retaining clips are secure. Apply firm even pressure on your module to attach it to its backplane connector. Never force your module into the slot.
Cover all unused slots with the Card Slot Filler, Allen-Bradley part number 1746-N2.
Terminal Block Removal
To remove the terminal block:
Using a screwdriver or needle-nose pliers, carefully unscrew and then pry the terminal block loose. When removing or installing the terminal block be careful not to damage the CJC sensors.
Chapter 2: Installing And Wiring Your Module 15
Figure 2.2. Terminal block diagram with CJC
sensors
CJC Sensors
CH0+
CH0­Shield 0/1
CH1+
CH1-
EXC4+
CH4+
CH4-
EXC4-
Shield 4/5 EXC5+ CH5+
CH5-
EXC5-
CJCB+ CJCB-
CJC Sensors
CAUTION
TB1
TB2
CJCA+
CJCA­CH2+
CH2-
SHIELD 2/3
CH3+
CH3-
EXC6+
CH6+
CH6­EXC6­SHIELD 6/7
EXC7+
CH7+
CH7­EXC7-
LEDS
Wiring Your Module
POSSIBLE EQUIPMENT OPERATION
!
Before wiring your module, always disconnect power from the SLC 500 system and from any other source to the module.
Failure to observe this precaution can cause unintended equipment operation and damage.
Follow these guidelines to wire your input signal cables:
• Power, input, and output (I/O) wiring must be in accordance with Class 1, Division 2 wiring methods [Article 501-4(b) of the National Electrical Code, NFPA 70] and in accordance with the authority having jurisdiction.
• Peripheral equipment must be suitable for the location in which it is used.
• Route the field wiring away from any other wiring and as far as possible from sources of electrical noise, such as motors,
16 SLC 500™ Universal Analog Input Module
transformers, contactors, and ac devices. As a general rule, allow at least 6 in. (about 15.2 cm) of separation for every 120 V of power.
• Routing the field wiring in a grounded conduit can reduce electrical noise further.
• If the field wiring must cross ac or power cables, ensure that they cross at right angles.
• To limit the pickup of electrical noise, keep thermocouple, RTD, millivolt, and milliamp signal wires as far from power and load lines as possible.
• For improved immunity to electrical noise, use Belden 8761 (shielded, twisted pair) or equivalent wire for millivolt sensors; or use shielded, twisted pair thermocouple extension lead wire specified by the thermocouple or RTD manufacturer. Using the incorrect type of thermocouple extension wire or not following the correct polarity may cause invalid readings.
Wiring RTD or Resistance Sensors to the NI8u Module
• There is one shield pin for every two input channels. All shields are internally connected, so any shield terminal can be used with any channel.
• Ground the shield drain wire at only one end of the cable. The preferred location is at the shield connections on the terminal block. (Refer to IEEE Std. 518, Section 6.4.2.7 or contact your sensor manufacturer for additional details.)
• Keep all unshielded wires as short as possible.
• To limit overall cable impedance, keep input cables as short as possible. Locate your I/O chassis as near the RTD or thermocouple sensors as your application will permit.
• Tighten screw terminals with care. Excessive tightening can strip a screw.
• Follow system grounding and wiring guidelines found in your SLC 500 Installation and Operation Manual.
The NI8u module supports two, three, and four wire RTDs or resistance inputs connected individually to the module (channels 4 through 7), as shown in the figure below.
ADD JUMPER
EXC4+
CH4+
CH4­EXC4-
Shield 4/5
Chapter 2: Installing And Wiring Your Module 17
2-Wire RTD Interconnection
RTD
RETURN
CABLE SHIELD
3-Wire RTD Interconnection
ADD JUMPER
EXC4+
CH4+
CH4-
EXC4-
Shield 4/5
EXC4+
CH4+
CH4-
EXC4-
Shield 4/5
RTD
SENSE
RETURN
CABLE SHIELD
4-Wire RTD Interconnection
RTD
SENSE POS
SENSE NEG
RETURN
CABLE SHIELD
These are:
* 2-wire RTDs, which are composed of 2 RTD lead wires (RTD and
Return)
* 3-wire RTDs, which are composed of a Sense and 2 RTD lead wires
(RTD and Return)
* 4-wire RTDs, which are composed of 2 Sense and 2 RTD lead wires
(RTD and Return).
In any RTD sensing system, it is important that the lead and sense wire resistances are matched as much as possible. The lead lengths, and their resulting impedances, must be matched and kept small to eliminate the introduction of connectivity errors. The 4-wire RTDs are the most accurate, with 2-wire RTDs being the most inaccurate. In 2-wire the lead resistance adds error to the resulting degree reading. With a 200µA
current source, 1 of lead resistance adds 200µV, or 3.45°C error, with the 100 385 alpha type. To gain an understanding of how lead
resistance affects RTD readings, the µV/C for each RTD type is listed below. The current source is 200µA.
18 SLC 500™ Universal Analog Input Module
RTD Type V/°C
100 Pt 385 58µV/ 200 Pt 385 116µV/ 500 Pt 385 290µV/ 1000 Pt 385 580µV/
100 Pt 3916 68µV/ 200 Pt 3916 136µV/ 500 Pt 3916 340µV/ 1000 Pt 3916 680µV/
10 Cu 426 4.3µV/ 120 Ni 618 110µV/
120 Ni 672 130µV/
°
C
°
C
°
C
°
C
°
C
°
C
°
C
°
C
°
C
°
C
°
C
The accuracies specified for the NI8u RTDs do not include errors due to lead resistance imbalances.
Important: To ensure temperature or resistance value accuracy, the resistance difference of the cable lead wires must be equal to or less than 0.01 ohms.
There are several ways to insure that the lead values match as closely as possible. They are as follows:
Preparing and Wiring the Cables
* Keep total lead resistance as small as possible, and less than 25 ohms.
* Use quality cable that has a small tolerance impedance rating.
* Use a heavy gauge lead wire which has less resistance per foot.
To prepare and connect cable leads and drain wires, follow these steps:
Signal Wires
Cable
Drain Wire
(At the module-end of the cable, extract
the drain wire but remove the foil shield.)
(Remove foil shield and drain wire
from sensor-end of cable.)
Signal Wires
1. At each end of the cable, strip some casing to expose individual wires.
2. Trim signal wires to 5-inch lengths beyond the cable casing. Strip about 3/16 inch (4.76 mm) of insulation to expose the ends of the wires.
3. At the module-end of the cables (see figure above):
Chapter 2: Installing And Wiring Your Module 19
- extract the drain wire and signal wires
- remove the foil shield
- bundle the input cables with a cable strap
4. Connect pairs of drain wires together, Channels 0 and 1, Channels 2 and 3, Channels 4 and 5, Channels 6 and 7. Keep drain wires as short as possible.
5. Connect the drain wires to the shield inputs of the terminal block.
Channel 0 and 1 drain wires to the shield 0/1 input pin
Channel 2 and 3 drain wires to the shield 2/3 input pin
Channel 4 and 5 drain wires to the shield 4/5 input pin
Channel 6 and 7 drain wires to the shield 6/7 input pin
6. Connect the signal wires of each channel to the terminal block. Important: Only after verifying that your connections are correct for each channel, trim the lengths to keep them short. Avoid cutting leads too short.
7. Connect the chassis ground terminal/lug to the nearest chassis mounting bolt with 14 gauge wire. (Looking at the face of the module, the terminal/lug is near the terminal block and above power supply PS2 on the primary side of the PCB.)
8. At the source-end of cables from mV devices:
- remove the drain wire and foil shield
- apply shrink wrap as an option
- connect to mV devices keeping the leads short
Important: If noise persists, try grounding the opposite end of the cable, instead (Ground one end only.)
Important: For CE compliance, Ferrite EMI Suppressors are needed on each channel’s terminal block connection. If remote CJCs are installed, shielded wire must be used and a Ferrite EMI suppressor is needed on each CJC input connection. The drain wire of the CJC cable must be connected to a shield connection at the module. Apply the suppressor close to the module terminal block, as shown below. A Steward Part 28B2024-0A0 or equivalent is recommended. The
Steward 28B2024-0A0 has an impedance of 157 at 25 MHz, 256 at
100 MHz, and can accomodate one turn of wire.
20 SLC 500™ Universal Analog Input Module
Figure 2.3 Ferrite EMI suppressor for CE
Note: Please refer to Appendix C for additional information on wiring and using grounded junction, ungrounded junction and exposed juction thermocouple types.
Figure 2.4 Terminal block diagram with input
compliance
Module
cable
THERMOCOUPLE, mA,
mV or V CABLE
4-WIRE RTD CABLE
3-WIRE RTD CABLE
THERMOCOUPLE, mA,
mV or V CABLE
TB1
CH0+
CH0-
Shield for CH0 and CH1
CH1+
CH1-
EXC4+
CH4+
CH4-
EXC4-
Shield for CH4 and CH5
EXC5+
CH5+
CH5-
EXC5-
CJCB+
CJCB-
TB2
CJC A+
CJC A -
CH2+
CH2-
Shield for CH2 and CH3
CH3+
CH3-
EXC6+
CH6+
CH6-
EXC6-
Shield for CH6 and CH7
EXC7+
CH7+
CH7-
EXC7-
Chapter 2: Installing And Wiring Your Module 21
The module also has a ground terminal TB1 which should be grounded to a chassis mounting bolt with 14 gauge wire.
Cold Junction Compensation (CJC)
CAUTION
!
To obtain accurate readings from each of the channels, the cold junction temperature (temperature at the module’s terminal junction between the thermocouple wire and the input channel) must be compensated for. Two cold junction compensating sensors have been integrated in the removable terminal block. They must remain installed to retain accuracy. If remote CJC compensation is desired, the sensors at the terminal block must be removed and the external sensors wired to the CJCA and CJCB terminals. The remote CJC sensors must be Analog Devices AD592CN T0-92 style temperature transducer devices. The module will not function with any other CJC sensor connected.
POSSIBLE EQUIPMENT OPERATION
Do not remove or loosen the cold junction compensating temperature transducers located on the terminal block unless you are connecting remote CJCs to the module. Both CJCs are critical to ensure accurate thermocouple input readings at each channel. The module will not operate in thermocouple mode if a CJC is not connected.
Failure to observe this precaution can cause unintended equipment operation and damage.
22 SLC 500™ Universal Analog Input Module
Chapter 3
Things To Consider Before Using Your Module
This chapter explains how the module and the SLC processor communicate through the processor’s I/O image tables. It also describes the module’s input filter characteristics. Topics discussed include:
• module ID code
• module addressing
• channel filter frequency selection
• Channel turn-on, turn-off, and reconfiguration times
• response to slot disabling
Module ID Code
Module Addressing
The module ID code is a unique number assigned to each type of 1746 I/O module. The ID defines for the processor the type of I/O module and the number of words used in the processor’s I/O image table.
With APS software, use the system I/O configuration display to manually enter the module ID when assigning the slot number during the configuration. Do this by selecting (other) from the list of modules on the system I/O configuration display and enter 3500, the ID code for the 1746sc-NI8u.
No special I/O configuration (SPIO CONFIG) is required. The module ID automatically assigns the correct number of input and output words.
If you are using different programming software package, refer to the documentation that came with your software.
The following memory map shows you how the SLC processor’s output and input tables are defined for the module.
24 SLC 500™ Universal Analog Input Module
Figure 3.1 Image table
SLC 5/0X
Data Files
Slot e
Output Image
Slot e
Input Image
Output
Scan
Input Scan
Bit 15 Bit 0 Address
Thermocouple
Module
Image Table
Output Image
8 Words
Input Image
8 Words
Bit 15 Bit 0 Address
Channel 0 Configuration Word
Channel 1 Configuration Word
Channel 2 Configuration Word
Channel 3 Configuration Word
Channel 4 Configuration Word
Channel 5 Configuration Word
Channel 6 Configuration Word
Channel 7 Configuration Word
Channel 0 Data or Status Word
Channel 1 Data or Status Word
Channel 2 Data or Status Word
Channel 3 Data or Status Word
Channel 4 Data or Status Word
Channel 5 Data or Status Word
Channel 6 Data or Status Word
Channel 7 Data or Status Word
Word 0 O:e.0
Word 1 O:e.1
Word 2 O:e.2
Word 3 O:e.3
Word 4 O:e.4
Word 5 O:e.5
Word 6 O:e.6
Word 7 O:e.7
Word 0 I:e.0
Word 1 I:e.1
Word 2 I:e.2
Word 3 I:e.3
Word 4 I:e.4
Word 5 I:e.5
Word 6 I:e.6
Word 7 I:e.7
Output Image - Configuration Words
Eight words of the SLC processor’s output image table are reserved for the module. Output image words 0-7 are used to configure the module’s input channels 0-7. Each output image word configures a single channel, and can be referred to as a configuration word. Each word has a unique address based on the slot number assigned to the module.
Example Address - If you want to configure channel 2 on the module located in slot 4 in the SLC chassis, your address would be O:4.2.
File type
Element
Delimiter
Slot
Word
O:4.2
Word
Delimiter
Chapter 4, Channel Configuration, Data, and Status, gives you detailed bit information about the data content of the configuration word.
Chapter 3: Things To Consider Before Using Your Module 25
Input Image - Data Words and Status Words
Eight words of the SLC processor’s input image table are reserved for the module. Input image words are multiplexed since each channel has one data word and one status word. The corresponding configuration word selects whether the channel status or channel data is in the input image word.
Status bits for a particular channel reflect the configuration settings that you entered into the configuration (output image) word for that channel. To receive valid status, the channel must be enabled and the module must have stored a valid configuration word for that channel.
Each input image word has a unique address based on the slot number assigned to the module.
Example Address - To obtain the status/data word of channel 2 (input word 2) of the module located in slot 4 in the SLC chassis use address I:4:2.
Channel Filter Frequency Selection
File type
Element
Delimiter
Slot
Word
I:4.2
Word
Delimiter
Chapter 4, Channel Configuration, Data, and Status, gives you detailed bit information about the content of the data word and the status word.
The universal module uses a digital filter that provides high frequency noise rejection for the input signals. The digital filter is programmable, allowing you to select from four filter frequencies for each channel. The digital filter provides the highest noise rejection at the selected filter frequency. The graphs to follow show the input channel frequency response for each filter frequency selection.
Selecting a low value (i.e. 10 Hz) for the channel filter frequency provides the best noise rejection for a channel, but it also increases the channel update time. Selecting a high value for the channel filter frequency provides lower noise rejection, but decreases the channel update time.
The following table shows the available filter frequencies, cut-off frequency, step response, and ADC effective resolution for each filter frequency.
26 SLC 500™ Universal Analog Input Module
Table 3.1 Cut-off frequency, step response time, and
effective resolution (based on filter frequency)
Filter Cut-Off Step ADC Effective
Frequency Frequency Response Resolution
10 Hz 2.62 Hz 300 ms 20.5 50 Hz 13.1 Hz 60 ms 19.0 60 Hz 15.72 Hz 50 ms 19.0
250 Hz 65.5 Hz 12 ms 15.5
The step response is calculated by a 3 x (1/filter frequency) settling time.
Channel Cut-Off Frequency
The channel filter frequency selection determines a channel’s cut-off frequency, also called the -3 dB frequency. The cut-off frequency is defined as the point on the input channel frequency response curve where frequency components of the input signal are passed with 3 dB of attenuation. All frequency components at or below the cut-off frequency are passed by the digital filter with less than 3 dB of attenuation. All frequency components above the cut-off frequency are increasingly attenuated, as shown in the graphs below.
The cut-off frequency for each input channel is defined by its filter frequency selection. The table above shows the input channel cut-off frequency for each filter frequency. Choose a filter frequency so that your fastest changing signal is below that of the filter’s cut-off frequency. The cut-off frequency should not be confused with update time. The cut-off frequency relates how the digital filter attenuates frequency components of the input signal. The update time defines the rate at which an input channel is scanned and its channel data word updated.
Chapter 3: Things To Consider Before Using Your Module 27
Figure 3.2 Signal attenuation with 10 Hz input filter
-3 dB
Amplitude (in dB)
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
-200 0 10 20 30 40 50 60 Hz
Signal Frequency
2.62 Hz
Figure 3.3 Signal attenuation with 50 Hz input filter
-3 dB
Amplitude (in dB)
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
-200 0 50 100 150 200 250 300 Hz
13.1 Hz
Signal Frequency
28 SLC 500™ Universal Analog Input Module
Figure 3.4 Signal attenuation with 60 Hz input filter
-3 dB
Amplitude (in dB)
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
-200 0 60 120 180 240 300 360 Hz
Signal Frequency
15.7 Hz
Figure 3.5 Signal attenuation with 250 Hz input filter
-3 dB
Amplitude (in dB)
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
-200 0 250 500 750 1000 1250 1500 Hz
Signal Frequency
65.5 Hz
Channel Step Response
The channel filter frequency determines the channel’s step response. The step response is time required for the analog input signal to reach 95% of its expected, final value given a full-scale step change in the input signal. This means that if an input signal changes faster than the channel step response, a portion of that signal will be attenuated by the channel filter. Table 6 shows the step response for each filter frequency.
Chapter 3: Things To Consider Before Using Your Module 29
Update Time
Channel 0 Disabled
Enabled
Sample
Channel 0
Update CJC
The universal module update time is defined as the time required for the module to sample and convert the input signals of all enabled input channels and make the resulting data values available to the SLC processor. It can be calculated by adding the sum of all enabled sample times, plus one CJC update time or one lead resistance update time.
Channel 1 Disabled Channel 2 Disabled
Enabled
Sample
Channel 1
Calculate
Previous
Enabled
The following table shows the channel sampling time for each filter frequency.
Table 3.2 Channel Sampling Time
Channel Sampling Time for Each Filter Frequency (all values ±1 msec)
250 Hz Filter 60 Hz Filter 50 Hz Filter 10 Hz Filter
Channel 7 Disabled
Sample
Channel 2
Calculate
Previous
Channel Sampling Time
Enabled
Channel 7
Sample
Calculate
Previous
Sample CJC or
Lead Resistance
Calculate
Previous
26 msec 64 msec 74 msec 314 msec
The times above include a settling time necessary between input channel readings.
In addition, on each module scan the module will sample either one CJC input or one lead resistance input if any enabled channel input type is a thermocouple, RTD, or resistance input. The CJC sampling time is 64 msec. The lead resistance sampling time is equal to the channel sampling time for that RTD. When both thermocouple inputs and RTD or resistance inputs are used, the module will alternate between sampling one CJC and one lead resistance.
The fastest module update time occurs when only one millivolt channel with a 250 Hz filter frequency is enabled.
Module update time = 26 msec
The slowest module update time occurs when eight channels, four thermocouples and four RTDs, each using a 10 Hz filter frequency, are enabled.
Module update time = 314 msec + 314 msec + 314 msec + 314 msec + 314 msec + 314 msec + 314 msec + 314 msec + 314 msec = 2.826 sec
30 SLC 500™ Universal Analog Input Module
Note: On alternate module scans, the 314 msec lead resistance sampling time would be replaced by a 64 msec CJC sampling time.
Update Time Calculation Example
The following example shows how to calculate the module update time for the given configuration:
Channel 0 configured for mV input at 250 Hz filter frequency, enabled Channel 1 configured for mV input at 250 Hz filter frequency, enabled Channel 2 configured for mV input at 50 Hz filter frequency, enabled Channel 3 disabled Channel 4 configured for RTD input at 50Hz filter frequency, enabled Channel 5 through 7 disabled
Using the values from the table above, add the sum of all enabled channel sample times, plus one 50 Hz lead resistance update time.
Channel 0 sampling time = 26 msec Channel 1 sampling time = 26 msec Channel 2 sampling time = 74 msec Channel 4 sampling time = 74 msec Lead Resistance Sampling time = 74 msec
Channel Turn-On, Turn-Off, and Reconfiguration Times
Auto-Calibration
Module update time = 274 msec
The time required for the module to recognize a new configuration for a channel is generally one module update time plus 1.865 msec per newly configured channel. If the filter frequency selected for the newly enabled, configured channel is new to the module, then auto­calibration will be performed following configuration recognition.
Turn-off time requires up to one module update time.
Reconfiguration time is the same as turn-on time.
Auto-calibration is performed by the module to correct for drift errors over temperature. Auto-calibration occurs immediately following configuration of a previously unselected filter frequency for the particular input path. If all enabled channels have the calibration disable configuration bit set to zero, auto-calibration also occurs as a continuous cycle, where every two minutes all the required filter frequencies and input paths are calibrated. There are three input paths in the system to accommodate all the input options: a low voltage input path,
Chapter 3: Things To Consider Before Using Your Module 31
a mid voltage input path, and a high voltage input path. The following table correlates input type to input path.
Input Type Input Path
4 to 20mA Mid
0 to 20mA Mid
± 50mV Low
± 100mV Low
± 500mV Mid
± 2V Mid
0 to 5V, 1-5V High
± 10V, 0-10V High
All Thermocouple Types Low
Pt 385 RTD, 100 Low Pt 385 RTD, 200Ω, 500Ω, 1000 Mid Pt 385 RTD, 100 Low Pt 385 RTD, 200Ω, 500Ω, 1000 Mid Cu 426 RTD, 10 Low Ni 618 RTD, 120 Low Ni 672 RTD, 120 Low
CJC Low
3000 Resistance Mid
Each input path supports four different filter frequencies: 10Hz, 50Hz, 60Hz and 250Hz. The following table indicates auto­calibration time based on the input path, and the selected filter frequency.
Input Path 250Hz Filter 60Hz Filter 50Hz Filter 10Hz Filter
Low 181mS 384mS 435mS 1.85S
Mid 181mS 384mS 435mS 1.85S
High 96mS 208mS 238mS 1.03S
CJC sensors are acquired through the low voltage input path at 60Hz, to maximize the trade-offs between resolution and update rate.
Once every two minutes, the module calibrates one of the input path and filter combinations on successive scans until all input path and filter combinations that are used have been calibrated. During auto-calibration, the module scan time will increase by the auto-calibration time.
Auto-calibration can be disabled by placing a one in any enabled channel’s auto-cal disable bit.
32 SLC 500™ Universal Analog Input Module
Response to Slot Disabling
By writing to the status file in the modular SLC processor, you can disable any chassis slot. Refer to your SLC programming manual for the slot disable/enable procedure.
CAUTION
!
Input Response
When a universal slot is disabled, the universal module continues to update its input image table. However, the SLC processor does not read input from a module that is disabled. Therefore, when the processor disables the universal module slot, the module inputs appearing in the processor image table remain in their last state, and the module’s updated image table is not read. When the processor re­enables the module slot, the current state of the module inputs are read by the processor during the subsequent scan.
Output response
The SLC processor may change the universal module output data (configuration) as it appears in the processor output image. However, this data is not transferred to the universal module. The outputs are held in their last state. When the slot is re-enabled, the data in the processor image is transferred to the universal module.
POSSIBLE EQUIPMENT OPERATION
Always understand the implications of disabling a module before using the slot disable feature.
Failure to observe this precaution can cause unintended equipment operation.
Channel Configuration
Chapter 4: Channel Configuration, Data, and Status 33
Chapter 4
Channel Configuration, Data, and Status
Read this chapter to:
• configure each input channel
• check each input channel’s configuration and status
Channel configuration words appear in the SLC controller’s output image table as shown below. Words 0-7 correspond to module channels 0-7.
After module installation, you must configure each channel to establish the way the channel operates (e.g., input type, temperature units, etc.). You configure the channel by setting bits in the configuration word using your programmer. We present bit descriptions next.
SLC Output Image (Configuration) Words
15
O:e.0
O:e.2
O:e.3
O:e.4
O:e.5
O:e.6
O:e.7
e = slot number of the module
0
Channel 0 Configuration Word
Channel 1 Configuration WordO:e.1
Channel 2 Configuration Word
Channel 3 Configuration Word
Channel 4 Configuration Word
Channel 5 Configuration Word
Channel 6 Configuration Word
Channel 7 Configuration Word
34 SLC 500™ Universal Analog Input Module
The configuration word default settings are all zero. Next, we describe how you set configuration bits of a channel configuration word to set up the following channel parameters:
• type of thermocouple , RTD, resistance, mV, V, or mA input
• RTD or resistance type of 2-wire, 3-wire or 4-wire
• data format such as engineering units, counts, or scaled for PID
• how the channel should respond to a detected open input circuit, if applicable
• filter frequency selection
• temperature units in °C or °F
• whether the channel is enabled or disabled
• whether auto-calibration is enabled or disabled
Channel Configuration Procedure
• whether status or data information is selected for the module’s input image table.
The channel configuration word consists of bit fields, the settings of which determine how the channel will operate. This procedure looks at each bit field separately and helps you configure a channel for operation. Refer to the chart on the following page and the bit field descriptions that follow for complete configuration information.
1. Determine which channels are used in your program and enable them. Place a one in bit 0 if the channel is to be enabled. Place a zero in bit 0 if the channel is to be disabled.
2. Determine the input device type (thermocouple, RTD, resistance, mV, V, or mA) for a channel and enter its respective 5-digit binary code in bit field 1-5 of the channel configuration word. Remember that only channels 4-7 support the RTD and resistance options. Make sure that the shunts are set accordingly for the input types specified.
3. Select a data format for the data word value. Your selection determines how the analog input value from the A/D converter will be expressed in the data word. Enter your 2-digit binary code in bit field 6­7 of the channel configuration word. Not all data formats apply to all
Chapter 4: Channel Configuration, Data, and Status 35
input types. Check table 11 to make sure you selected a valid combination.
4. Determine the desired state for the channel data word if an open circuit condition is enabled and detected for that channel. Enter the 2-digit binary code in bit field 8-9 of the channel configuration word. Not all input types support open circuit detection. Review the “Open Circuit State” description on page 43 to verify applicability.
5. If the channel is configured for thermocouple inputs, RTD or the CJC sensor, determine if you want the channel data word to read in degrees Fahrenheit or degrees Celsius and enter a one or a zero in bit 10 of the configuration word. If the channel is configured for a mV, V, mA, or resistance analog sensor, enter a zero in bit 9.
6. Determine the desired input filter frequency for the channel and enter
the 2-digit binary code in bit field 11-12 of the channel configuration word. A lower filter frequency increases the channel update time, but also increases the noise rejection and channel resolution. A higher filter frequency decreases the channel update time, but also decreases the noise rejection and effective resolution.
7. If an RTD or resistance input type was selected, enter the digit binary
code corresponding to 2- or 4-wire, or 3-wire, RTD inputs in bit 13. If a thermocouple, mV, V, or mA type is used, enter a 0 in bit 13.
8. If auto-calibration is desired, place a zero in bit 14. If auto-calibration
is not desired, place a one in bit 14.
9. Determine whether the channel input image word should contain data
or status. Place a one in bit 15 if channel data is desired. Place a zero in bit 15 if status is desired.
10. Build the channel configuration word for every channel on each
universal module repeating the procedures given in steps 1-9.
11.Enter this configuration into your ladder program and copy it to the
universal module.
Each channel has a word in the module’s output image which determines the way that channel functions. Channels 0 through 3 may be configured for current, voltage or thermocouple input types. No RTD or resistance input types are allowed on those channels. Channels 4 through 7 may be configured for current, voltage, thermocouple, RTD or resistance inputs. The definition of the bits in the configuration words are described in the charts below.
36 SLC 500™ Universal Analog Input Module
Table 4.1 Channel Configuration Word (O:e.3:0)
Channel 3:0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Channel Channel disable 0 Enable Channel enable 1
4 to 20 mA 0 0 0 0 0 0 to 20 mA 0 0 0 0 1 ± 0.05 V 0 0 0 1 0 ± 0.10 V 0 0 0 1 1 ± 0.50 V 0 0 1 0 0 ± 2.0 V 0 0 1 0 1
Input 1 to 5V 0 0 1 1 1 Type 0 to 10V 0 1 0 0 0
Data Engineering Units x10 0 1
Format Scaled for PID 1 0
Open Max. on open circuit 0 1 Circuit Min. on open circuit 1 0
Temperature Degrees C 0
Units Degrees F 1
Channel 10 Hz input filter 0 0
filter 50 Hz input filter 0 1
freq. 60 Hz input filter 1 0
Unused 0
Auto-cal Enabled 0
Input Image Status word 0 Type Data word 1
0 to 5 V 0 0 1 1 0
±10V 0 1 0 0 1 Thermocouple Type J 0 1 0 1 0 Thermocouple Type K 0 1 0 1 1 Theromcouple Type T 0 1 1 0 0 Thermocouple Type E 0 1 1 0 1 Thermocouple Type R 0 1 1 1 0 Thermocouple Type S 0 1 1 1 1 Thermocouple Type B 1 0 0 0 0 Thermocouple Type N 1 0 0 0 1 Invalid 1 0 0 1 x Invalid 1 0 1 x x Invalid 1 1 0 x x Invalid 1 1 1 0 x Thermocouple Type C 1 1 1 1 0 CJC 1 1 1 1 1
Engineering Units x1 0 0
Proportional counts 1 1
Zero on open circuit 0 0
Disabled 1 1
250 Hz input filter 1 1
Disabled 1
Chapter 4: Channel Configuration, Data, and Status 37
Table 4.2 Channel Configuration Word (O:e.7:4)
Channel 7:4 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Channel Channel disable 0 Enable Channel enable 1
Input 1 to 5 V 0 0 1 1 1 Type 0 to 10 V 0 1 0 0 0
Data Engineering Units x10 0 1
Format Scaled for PID 1 0
Open Max. on open circuit 0 1 Circuit Min. on open circuit 1 0
Temperature Degrees C 0
Units Degrees F 1
Channel 10 Hz input filter 0 0
filter 50 Hz input filter 0 1
freq. 60 Hz input filter 1 0
RTD Type 2 or 4 wire 0
Auto-cal Enabled 0
Input Image Status word 0 Type Data word 1 The configuration word default setting is all zeros. Whan a voltage or current input type is selected, the bit setting for
temperature units is ignored.
4 to 20 mA 0 0 0 0 0 0 to 20 mA 0 0 0 0 1 ± 0.05 V 0 0 0 1 0 ± 0.10 V 0 0 0 1 1 ± 0.50 V 0 0 1 0 0 ± 2.0 V 0 0 1 0 1 0 to 5 V 0 0 1 1 0
±10V 01001 Thermocouple Type J 0 1 0 1 0 Thermocouple Type K 0 1 0 1 1 Thermocouple Type T 0 1 1 0 0 Thermocouple Type E 0 1 1 0 1 Thermocouple Type R 0 1 1 1 0 Thermocouple Type S 0 1 1 1 1 Thermocouple Type B 1 0 0 0 0 Thermocouple Type N 1 0 0 0 1
RTD 100
RTD 200 Ω Pt 385 1 0 0 1 1 RTD 500 Ω Pt 385 1 0 1 0 0 RTD 1000 Ω Pt 385 1 0 1 0 1 RTD 100 Ω Pt 3916 1 0 1 1 0 RTD 200 Ω Pt 3916 1 0 1 1 1 RTD 500 Ω Pt 3916 1 1 0 0 0 RTD 1000 Ω Pt 3916 1 1 0 0 1 RTD 10 Ω Cu 426 1 1 0 1 0 RTD 120 Ω Ni 618 1 1 0 1 1 RTD 120 Ω Ni 672 1 1 1 0 0 Resistance 3000 Thermocouple Type C 1 1 1 1 0 CJC 11111
Engineering Units x1 0 0
Proportional counts 1 1
Zero on open circuit 0 0
Disabled 1 1
385 1 0 0 1 0
111 01
250 Hz input filter 1 1
3 wire 1
Disabled 1
38 SLC 500™ Universal Analog Input Module
Select Channel Enable (Bit 0)
Use the channel enable bit to enable a channel. The universal module only scans those channels that are enabled. To optimize module operation and minimize throughput times, unused channels should be disabled by setting the channel enable bit to zero.
When set (1) the channel enable bit is used by the module to read the configuration word information you have selected. While the enable bit is set, modification of the configuration word may lengthen the module update time for one cycle. If any change is made to the configuration word, the change will be reflected in the status word before new data is valid (described in the last section of this chapter).
While the channel enable bit is cleared (0), the associated channel data/ status word values are cleared. After the channel enable bit is set, the associated channel data/status word remains cleared until the universal module sets the channel status bit (bit 0) in the channel status word.
Select Input Types (Bits 1-5)
The input type bit field lets you configure the channel for the type of input device you have connected to the module. Valid input devices are types J,
K, T, E, R, S, B, N, and C thermocouple sensors, 100Ω, 200Ω, 500Ω, and 1000 Pt 385 RTDs; 100Ω, 200, 500, and 1000Pt 3916 RTDs; 10 Cu 426 RTD, 120 Ni 618 RTD, and 120Ω Ni 672 RTD sensors; 3000
resistance devices and ±50mV, ± 100mV, ±500mV, ±2V, 0-5V, 1-5V, 0­10V, ±10V, 0-20mA, and 4-20mA analog input signals. The channel can also be configured to read the cold-junction temperature calculated for that specific channel. When the cold-junction compensation (CJC) temperature is selected, the channel ignores the physical input signal. RTD and resistance inputs can only be supported by channels 4-7.
Select Data Format (Bits 6 and 7)
The data format bit field lets you define the expressed format for the channel data word contained in the module input image. The data types are engineering units, scaled-for-PID, and proportional counts.
The engineering units allow you to select from two resolutions, x1 or x10. For engineering units x1, values are expressed in 0.1 degrees,
0.01mV or 0.001mA. For engineering units x10, values are expressed in
1.0 degrees, 1mV or 0.01mA. (Use the x10 setting to produce
temperature readings in whole degrees Celsius or Fahrenheit.) You will notice in Table 11 that not all input types can support the x1 format.
The scaled-for-PID value is the same for millivolt, milliamp, thermocouple, RTD, resistance,) and CJC input types. The input signal range is proportional to your selected input type and scaled into a 0-16,383 range, which is standard to the SLC PID algorithm.
Chapter 4: Channel Configuration, Data, and Status 39
The proportional counts are scaled to fit the defined temperature, voltage, or current range. The input signal range is proportional to your selected input and scaled into a (-32,768 to 32,767) range.
Using Scaled-for-PID and Proportional Counts
The universal module provides eight options for displaying input channel data. These are 0.1°F, 0.1°C, 1°F, 1°C, 0.01 mV, 0.1 mV, Scaled-for-PID, and Proportional Counts. The first six options represent real Engineering Units provided/displayed by the 1746sc-NI8u, and do not require explanation. The Scaled-for-PID and Proportional Counts selections provide the highest NI8u display resolution, but also require you to manually convert the channel data to real Engineering Units.
The equations below show how to convert from Scaled-for-PID to Engineering Units, Engineering Units to Scaled-for-PID, Proportional Counts to Engineering Units, and Engineering Units to Proportional Counts. To perform the conversions, you must know the defined temperature or millivolt range for the channel’s input type. Refer to the Channel Data Word Format table on the following page. The lowest possible value for an input type is S
.
S
HIGH
, and the highest possible value is
LOW
It is important to note that the Scaled for PID and proportional counts format do not linearize inputs that are not linear. The module assumes that current and voltage inputs are linear prior to insertion into the universal module’s input stage. Thermocouple inputs are cold junction compensated, and are linearized in their temperature conversion process through the NIST ITS-90 tables. RTDs are converted from their resistance value to degrees according to their associated IEC or JISC standards.
Scaling ExamplesScaling Examples
Scaling Examples
Scaling ExamplesScaling Examples
Scaled-for-PID to Engineering Units
Equation: Engr Units Equivalent = S
Solution: Engr Units Equivalent = -210°C + [(760°C-(-210°C)) x (3421/16384)] = -7.46°C.
+ [(S
LOW
Assume type J input type, scaled-for-PID display type, channel data = 3421.
Want to calculate °C equivalent.
From Channel Data Word Format table, S
HIGH-SLOW)
x (Scaled-for-PID value displayed/16384)]
= -210°C and S
LOW
HIGH
Engineering Units to Scaled-for-PID
Equation: Scaled-for-PID Equivalent = 16384 x [(Engineering Units desired -S
LOW
)/(S
HIGH-SLOW
)]
= 760°C.
Assume type J input type, scaled-for-PID display type, desired channel
temp. = 344°C.
Want to calculate Scaled-for-PID equivalent.
From Channel Data Word Format table, S
Solution: Scaled-for-PID Equivalent = 16384 x [(344°C - (-210°C))/(760°C - (-210°C))] = 9357
= -210°C and S
LOW
= 760°C.
HIGH
40 SLC 500™ Universal Analog Input Module
Proportional Counts to Engineering Units
Equation: Engr Units Equivalent = S
LOW
+ {(S
HIGH-SLOW
) x [(Proportional Counts value displayed + 32768)/65536]}
Assume type E input type, proportional counts display type, channel data =
21567.
Want to calculate °F equivalent.
From Channel Data Word Format table, S
= -454°F an d S
LOW
HIGH
=1832°F
Solution: Engr Units Equivalent = -454°F + {[1832°F -(-454°F)] x [(21567 + 32768)/65536]} = 1441.3°F
Engineering Units to Proportional Counts
Equation: Proportional Counts Equivalent = {65536 x[(Engineering Units desired - S
Assume type E input type, proportional counts display type, desired channel
temp. = 1000°F.
Want to calculate Proportional Counts equivalent.
From Channel Data Word Format table, S
= -454°F and S
LOW
Solution: Proportional Counts Equivalent = {65536 x[{1000°F - (-454°F))/(1832°F - (-454°F))]} - 32768 = 8916.
LOW
)/(S
HIGH-SLOW
= 1832°F.
HIGH
)]} -32768
Chapter 4: Channel Configuration, Data, and Status 41
Table 4.3 1746sc-NI8u Universal Module ­ Channel Data Word Format
Data Format
Input Engineering Units x 10 Engineering Units x 1 Proportional
Type ° Celsius ° Fahrenheit ° Celsius ° Fahrenheit Scaled-for-PID Counts
4-20 mA * +400 to +2,000 +4,000 to +20,000 0 to 16,383 -32,768 to 32,767
0-20 mA * 0 to +2,000 +0 to +20,000 0 to 16,383 -32,768 to 32,767
± 0.05 V * -500 to +500 -5,000 to +5,000 0 to 16,383 -32,768 to 32,767
± 0.10 V * -1,000 to +1,000 -10,000 to +10,000 0 to 16,383 -32,768 to 32,767
± 0.50 V * -5,000 to +5,000 N/A 0 to 16383 -32,768 to 32,767
± 2.0 V * -2,000 to +2,000 -20,000 to +20,000 0 to 16,383 -32,768 to 32,767
0-5 V * 0 to +5,000 N/A 0 to 16,383 -32,768 to 32,767
1-5 V * +1,000 to +5,000 N/A 0 to 16,383 -32,768 to 32,767
0-10 V * 0 to +10,000 N/A 0 to 16,383 -32,768 to 32,767
±10 V * -10,000 to +10,000 N/A 0 to 16,383 -32,768 to 32,767
J -210 to 760 -346 to 1,400 -2,100 to 7,600 -3,460 to 14,000 0 to 16,383 -32,768 to 32,767
K -270 to 1,370 -454 to 2,498 -2,700 to 13,700 -4,540 to 24,980 0 to 16,383 -32,768 to 32,767
T -270 to 400 -454 to 752 -2,700 to 4,000 -4,540 to 7,520 0 to 16,383 -32,768 to 32,767
E -270 to 1,000 -454 to 1,832 -2,700 to 10,000 -4,540 to 18,320 0 to 16,383 -32,768 to 32,767
R 0 to 1,768 32 to 3,214 0 to 17,680 320 to 32,140 0 to 16,383 -32,768 to 32,767
S 0 to 1,768 32 to 3,214 0 to 17,680 320 to 32,140 0 to 16,383 -32,768 to 32,767
B 300 to 1,820 572 to 3,308 3,000 to 18,200 5,720 to 32,767** 0 to 16,383 -32,768 to 32,767
N 0 to 1,300 32 to 2,372 0 to 13,000 320 to 23,720 0 to 16,383 -32,768 to 32,767
C 0 to 2315 32 to 4199 0 to 23,150 32 to 32767** 0 to 16,383 -32, 768 to 32-767
10Ω Cu 426 -100 to 260 -148 to 500 -1,000 to 2,600 -1,480 to 5,000 0 to 16,383 -32, 768 to 32-767
120 Ω Ni 618 -100 to 260 -148 to 500 -1,000 to 2,600 -1,480 to 5,000 0 to 16,383 -32, 768 to 32-767
120 Ω Ni 672 -80 to 260 -112 to 500 -800 to 2,600 -1,120 to 5,000 0 to 16,383 -32, 768 to 32-767
3000Ω* 0 to 3,000 0 to 30,000 0 to 16,383 -32, 768 to 32-767
100Ω Pt 385 -200 to 850 -328 to 1,562 -2,000 to 8,500 -3,280 to 15,620 0 to 16,383 -32,768 to 32,767
200Ω Pt 385 -200 to 750 -328 to 1,382 -2,000 to 7,500 -3,280 to 13,820 0 to 16,383 -32,768 to 32,767
500Ω Pt 385 -200 to 850 -328 to 1,562 -2,000 to 8,500 -3,280 to 15,620 0 to 16,383 -32,768 to 32,767
1,000Ω Pt 385 -200 to 850 -328 to 1,562 -2,000 to 8,500 -3,280 to 15,620 0 to 16,383 -32,768 to 32,767
100Ω Pt 3916 -200 to 630 -328 to 1,166 -2,000 to 6,300 -3,280 to 11,660 0 to 16,383 -32,768 to 32,767
200Ω Pt 3916 -200 to 630 -328 to 1,166 -2,000 to 6,300 -3,280 to 11,660 0 to 16,383 -32,768 to 32,767
500Ω Pt 3916 -200 to 630 -328 to 1,166 -2,000 to 6,300 -3,280 to 11,660 0 to 16,383 -32,768 to 32,767
1,000Ω Pt 3916 -200 to 630 -328 to 1,166 -2,000 to 6,300 -3,280 to 1,1660 0 to 16,383 -32,768 to 32,767
C JC -25 to 105 -13 to 221 -250 to 1,050 -130 to 2,210 0 to 16,383 -32,768 to 32,767
* When current, voltage, or resistance input types are selected, the temperature setting is ignored and does not affect the data format.
** When Type B or Type C thermocouples cannot be represented in engineering units x 1 in °F above 3276.6°F, the module’s software will treat it as an over range condition if that channel has input to full scale.
42 SLC 500™ Universal Analog Input Module
Table 4.4 1746sc-NI8u Thermocouple Module -
Channel Data Word Resolution
Data Format
Input Engineering Units x 10 Engineering Units x 1 Scaled-for-PID Proportional Counts Type ° Celsius ° Fahrenheit ° Celsius ° Fahrenheit ° Celsius ° Fahrenheit ° Celsius ° Fahrenheit
0-20mAn0.01mA/step 0.01mA/step 0.001mA/step 0.001mA/step 1.221µA/step 1.221µA/step 0.3052µA/step 0.3052µA/step
4-20mAn0.01mA/step 0.01mA/step 0.001mA/step 0.001mA/step 0.9766µA/step 0.9766µA/step 0.2441µA/step 0.2441µA/step
±0.05V
n
0.1mV/step 0.1mV/step 0.01mV/step 0.01mV/step 6.104µV/step 6.104µV/step 1.526µV/step 1.526µV/step
±0.100Vn0.1mV/step 0.1mV/step 0.01mV/step 0.01mV/step 12.21µV/step 12.21µV/step 3.052µV/step 3.052µV/step
±0.5V
n
0.1mV/step 0.1mV/step N/A N/A 61.04µV/step 61.04µV/step 15.26µV/step 15.26µV/step
±2.0V
n
0.001V/step 0.001V/step 0.01mV/step 0.01mV/step 244.1µV/step 244.1µV/step 61.04µV/step 61.04µV/step
0-5V
n
0.001V/step 0.001V/step N/A N/A 305.2µV/step 305.2µV/step 76.29µV/step 76.29µV/step
1-5V
n
0.001V/step 0.001V/step N/A N/A 244.1µV/step 244.1µV/step 61.04µV/step 61.04µV/step
0-10V
n
0.001V/step 0.001V/step N/A N/A 610.4µV/step 610.4µV/step 152.6µV/step 152.6µV/step
±10V
n
0.001V/step 0.001V/step N/A N/A 1.221mV/step 1.221mV/step 305.2µV/step 305.2µV/step
100Ω Pt 385 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.06409°C/step 0.01154°F/step 0.01602°C/step 0.02884°F/step
200Ω Pt 385 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.06409°C/step 0.01154°F/step 0.01602°C/step 0.02884°F/step
500Ω Pt 385 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.06409°C/step 0.01154°F/step 0.01602°C/step 0.02884°F/step
1,000Ω Pt 385 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.06409°C/step 0.01154°F/step 0.01602°C/step 0.02884°F/step
100Ω Pt 3916 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.05066°C/step 0.09119°F/step 0.01266°C/step 0.02280°F/step
200Ω Pt 3916 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.05066°C/step 0.09119°F/step 0.01266°C/step 0.02280°F/step
500Ω Pt 3916 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.05066°C/step 0.09119°F/step 0.01266°C/step 0.02280°F/step
1,000Ω Pt 3916 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.05066°C/step 0.09119°F/step 0.01266°C/step 0.02280°F/step
10Ω Cu 426 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.0220°C/step 0.0396°F/step 0.0055°C/step 0.00990°F/step
120Ω Ni 618 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.0220°C/step 0.0396°F/step 0.0055°C/step 0.00990°F/step
120Ω Ni 672 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.0208°C/step 0.0374°F/step 0.0052°C/step 0.00993°F/step
3,000
J 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.0592°C/step 0.1066°F/step 0.0148°C/step 0.0266°F/step
K 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.1001°C/step 0.1802°F/step 0.0250°C/step 0.0450°F/step
T 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.0409°C/step 0.0736°F/step 0.0102°C/step 0.0184°F/step
E 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.0775°C/step 0.1395°F/step 0.0194°C/step 0.0349°F/step
R 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.1079°C/step 0.1942°F/step 0.0270°C/step 0.0486°F/step
S 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.1079°C/step 0.1942°F/step 0.0270°C/step 0.0486°F/step
B 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.0928°C/step 0.1670°F/step 0.0232°C/step 0.0417°F/step
N 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.0793°C/step 0.1428°F/step 0.0198°C/step 0.0357°F/step
C 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.1413°C/step 0.2543°F/step 0.0353°C/step 0.0636°F/step
CJ C 1°C/step 1°F/step 0.1°C/step 0.1°F/step 0.0079°C/step 0.0143°F/step 0.0020°C/step 0.0036°F/step
Sensor
1Ω/step 1Ω/step 0.1Ω/step 0.1Ω/step 0.183Ω/step 0.183Ω/step 0.0458Ω/step 0.0458Ω/step
n
When millivolts or resistance are selected, the temperature setting is ignored. Analog input data is the same for either °C or °F selection.
Chapter 4: Channel Configuration, Data, and Status 43
Important: Data resolution is not equivalent to data accuracy. Data
resolution merely indicates what a bit-weight is in any given input type and data format combination. Input accuracy of ±50µV may span multiple steps for PID and Proportional Counts data types. As an example a Type B thermocouple temperature range of 0 to 1820°C provides a voltage input range of 0 to 13.82mV to the NI8u. This is a very small input range and when it is scaled to PID or proportional counts ranges a small input change will result in many counts being changed.
Select Open Circuit State (Bits 8 and 9)
The open-circuit bit field lets you define the state of the channel data word when an open-circuit condition is detected for that channel. The open circuit does not apply to the 0-5V, 1-5V, 0-10V, ±2V, ±10V, or 0-20mA input types and should be disabled when those types are selected, or else a configuration error will result. It can be enabled for all other types, including the CJC input. This feature can be disabled by selecting the disable option.
An open circuit condition occurs when the input path is physically separated or open. For thermocouples or RTDs, either the sensor or the extension wire may be broken. The voltage or current input wire may be cut or disconnected from the terminal block. For RTDs only, a short circuit of less than 3 ohms will also flag this error.
If either of the two CJC devices are removed from the module wiring terminal, any input channel configured for either a thermocouple or CJC temperature input will be placed in an open circuit condition. An input channel configured for millivolt, volt, milliamp, or RTD input is not affected by CJC open-circuit conditions.
The results of the data word in an open-circuit condition depend upon the selection of bits 8 and 9.
If zero is selected, the channel data word is forced to 0 during an open­circuit condition.
Selecting maximum forces the channel data word value to its full scale value during an open-circuit condition. The full scale value is determined by the selected input type and data format.
Selecting minimum forces the channel data word value to its low scale value during an open-circuit condition. The low scale value is determined by the selected input type and data format.
When the open-circuit option applies, disabling the open-circuit selection may result in unintended operation on a failure because the returned data word value is unknown. The open circuit error bit and the channel LED will flag the condition until the error is resolved.
44 SLC 500™ Universal Analog Input Module
For example, if channel one is configured as a thermocouple type when the CJC breaks in an open-circuit condition, if open-circuit detection is disabled, the data word will remain unchanged. If the circuit selection is set at minimum, the data word will be set to the low scale value for the range and format.
Select Temperature Units (Bit 10)
The temperature units bit lets you select temperature engineering units for thermocouple, RTD, and CJC input types. Units are either degrees Celsius (°C) or degrees Fahrenheit (°F). This bit field is only active for thermocouple, RTD and CJC input types. It is ignored when millivolt or current inputs types are selected.
Select Channel Filter Frequency (Bits 11 and 12)
The channel filter frequency bit field lets you select one of four filters available for a channel. The filter frequency affects the channel update time and noise rejection characteristics. A smaller filter frequency increases the channel update time, but also increases the noise rejection and channel resolution. A larger filter frequency decreases the noise rejection, but also decreases the channel update time and channel resolution.
• 250 Hz setting provides minimal noise filtering.
• 60 Hz setting provides 60 Hz AC line noise filtering.
• 50 Hz setting provides 50 Hz AC line noise filtering.
• 10 Hz setting provides both 50 Hz and 60 Hz AC line noise filtering.
When a CJC input type is selected, this field is ignored. To maximize the speed versus resolution trade-off, CJC inputs are sampled at 60 Hz.
Select RTD Type (Bit 13)
The selection for RTD or resistance type is only valid for channels 4 through 7, and should be set to zero for channels 0 through 3.
If the Input Type selection defines an RTD or resistance type, then the wire type also needs to be specified. The universal module converts the RTD or resistance type input data differently according to whether the 2 or 4 wire method is used, or the 3 wire method is used.
Select Auto-Calibration Disable (Bit 14)
The auto-calibration disable bit allows you to disable periodic auto­calibration. Set this bit on any enabled channel to disable auto-calibration for all channels. Clear this bit on all enabled channels to enable auto­calibration on all channels.
Channel Data/Status Word
Module Input Image (Data/Status) Words
O:e.0
Chapter 4: Channel Configuration, Data, and Status 45
Select Input Image Type (Bit 15)
The input image type bit allows you to select data or status information in the channel’s input image word. When set (1) the module places channel data in the corresponding input image word. When the bit is cleared (0) the module places channel status in the corresponding input image word.
The actual thermocouple, RTD, resistance, millivolt, volt, or milliamp input data values or channel status reside in I:e.0 through I:e.7 of the universal module input image file. The data values present will depend on the input type and data formats you have selected. When an input channel is disabled, its data word is reset (0).
15
Channel 0 Channel Data/Status Word
0
O:e.2
O:e.3
O:e.4
O:e.5
O:e.6
O:e.7
Channel Status Checking
Channel 1 Channel Data/Status WordO:e.1
Channel 2 Channel Data/Status Word
Channel 3 Channel Data/Status Word
Channel 4 Channel Data/Status Word
Channel 5 Channel Data/Status Word
Channel 6 Channel Data/Status Word
Channel 7 Channel Data/Status Word
The input image of the module is 8 words. Since there are 8 channels with a data word and a status word for each channel, the input image information is multiplexed. The information in the input image is the channel data word if bit 15 of the channel’s configuration word is 1. The information in the input image is the channel status word if bit 15 of the channel’s configuration word is 0.
You can use the information provided in the status word to determine if the input configuration data for any channel is valid per your configuration in O:e.0 through O:e.7.
46 SLC 500™ Universal Analog Input Module
The channel status can be analyzed bit by bit. In addition to providing information about an enabled or disabled channel, each bit’s status (0 or 1) tells you how the input data from the analog sensor connected to a specific channel will be translated for your application. The bit status also informs you of any error condition and can tell you what type of error occurred.
The status word definitions for channels 0 through 3 do not include the RTD or resistance support that is provided by channels 4 through 7. The charts on the following pages provide a bit by bit examination of the respective status words.
Table 4.5 Channel 0-7 Status Word (I:e.0 through
I:e.7) - Bit Definitions
Channel 3:0 15 14 13 12 11 10 9 8 7 6 5 4 3210
Channel Channel disabled 0 Status Channel enable 1
Input 1 to 5V 0011 1 Type 0 to 10V 0100 0
Data Engineering Units x10 0 1
Format Scaled for PID 1 0
Open Max. on open circuit 0 1 Circuit Min. on open circuit 1 0
Channel 10 Hz input filter 0 0
filter 50 Hz input filter 0 1
freq. 60 Hz input filter 1 0
Open circuit No error 0
Under range No error 0
error Under range condition 1 Over range No error 0 error Over range condition 1 Channel No error 0 error Channel error 1
4 to 20 mA 0 0 0 0 0 0 to 20 mA 0 0 0 0 1 ± 0.05 V 0001 0 ± 0.10 V 0001 1 ± 0.50 V 0010 0 ± 2.0 V 0010 1 0 to 5 V 0011 0
±10V 0100 1 Thermocouple Type J 0 1 0 1 0 Thermocouple Type K 0 1 0 1 1 Theromcouple Type T 0 1 1 0 0 Thermocouple Type E 0 1 1 0 1 Thermocouple Type R 0 1 1 1 0 Thermocouple Type S 0 1 1 1 1 Thermocouple Type B 1 0 0 0 0 Thermocouple Type N 1 0 0 0 1 Invalid 1001 x Invalid 101x x Invalid 110x x Invalid 1110 x Thermocouple Type C 1 1 1 1 0 CJC temperature 1 1 1 1 1
Engineering Units x1 0 0
Proportional counts 1 1
Zero on open circuit 0 0
Disabled 1 1
250 Hz input filter 1 1
Open circuit detected 1
Chapter 4: Channel Configuration, Data, and Status 47
Channel 7:4 15 14 13 12 11 10 9 8 7 6 5 4 3210
Channel Channel disabled 0 Status Channel enable 1
4 to 20 mA 0 0 0 0 0 0 to 20 mA 0 0 0 0 1 ± 0.05 V 0001 0 ± 0.10 V 0001 1 ± 0.50 V 0010 0 ± 2.0 V 0010 1
Input 1 to 5 V 0011 1 Type 0 to 10 V 0 1 0 0 0
Data Engineering Units x10 0 1
Format Scaled for PID 1 0
Open Max. on open circuit 0 1 Circuit Min. on open circuit 1 0
Channel 10 Hz input filter 0 0
filter 50 Hz input filter 0 1
freq. 60 Hz input filter 1 0
Open circuit No error 0
Under range No error 0
error Under range condition 1 Over range No error 0 error Over range condition 1 Channel No error 0 error Channel error 1
0 to 5 V 0011 0
±10V 0100 1 Thermocouple Type J 0 1 0 1 0 Thermocouple Type K 0 1 0 1 1 Thermocouple Type T 0 1 1 0 0 Thermocouple Type E 0 1 1 0 1 Thermocouple Type R 0 1 1 1 0 Thermocouple Type S 0 1 1 1 1 Thermocouple Type B 1 0 0 0 0 Thermocouple Type N 1 0 0 0 1
RTD 100
RTD 200 RTD 500 RTD 1000 RTD 100 RTD 200 RTD 500 RTD 1000 RTD 10 RTD 120 RTD 120 Resistance 3000 Thermocouple Type C 1 1 1 1 0 CJC temperature 1 1 1 1 1
Engineering Units x1 0 0
Proportional counts 1 1
Zero on open circuit 0 0
Disabled 1 1
250 Hz input filter 1 1
Open circuit detected 1
385 1 0 0 1 0
Pt 385 1 0 0 1 1
Pt 385 1 0 1 0 0
Pt 385 1 0 1 0 1
Pt 3916 1 0 1 1 0
Pt 3916 1 0 1 1 1
Pt 3916 1 1 0 0 0
Pt 3916 1 1 0 0 1
Cu 426 1 1 0 1 0
Ni 618 1 1 0 1 1
Ni 672 1 1 1 0 0
1110 1
48 SLC 500™ Universal Analog Input Module
Important: If the channel for which you are seeking status is disabled,
all bit fields are cleared. The status word for any disabled channel is always 0000 0000 0000 0000 regardless of any previous setting that may have been made to the configuration word.
Explanations of the status conditions follow.
Channel Status (Bit 0)
The channel status bit indicates operational state of the channel. When the channel enable bit is set in the configuration word (bit 0), the universal module configures the selected channel and takes a data sample for the channel data word before setting this bit in the status word.
Input Type Status (Bits 1-5)
The input type bit field indicates what type of input signal you have configured for the channel. This field reflects the input type defined in the channel configuration word.
Data Format Type Status (Bits 6 and 7)
The data format bit field indicates the data format you have defined for the channel. This field reflects the data type selected in bits 6 and 7 of the channel configuration word.
Open Circuit Type Status (Bits 8 and 9)
The open-circuit bit field indicates how you have defined the open circuit bits configuration word, and therefore, the response of the universal module to an open-circuit condition. This feature does not apply to the 0-5 V, 1-5 V, 0-10 V, ±2 V, ±10 V, or 0-20mA input ranges, and a properly configured channel of those types will give the disabled status. It applies to all others, including CJC temperature input.
Channel Filter Frequency (Bits 10 and 11)
The channel filter frequency bit field reflects the filter frequency you selected in the configuration word.
Open Circuit Error (Bit 12)
This bit is set (1) whenever a configured channel detects an open-circuit condition at its input. Short circuited RTD inputs will also flag this error condition. A short circuit for RTDs exist when the module reads less than 3 ohms across the RTD input. An open-circuit at the CJC sensor will also flag this error if the channel input type is either thermocouple or CJC temperature. A range error on the CJC sensor will also flag this bit if the input type is a thermocouple type.
Chapter 4: Channel Configuration, Data, and Status 49
Under-Range Error (Bit 13)
This bit is set (1) whenever a configured channel detects an under-range condition for the channel data. An under-range condition exists when the input value is equal to or below the specified lower limit of the particular sensor connected to that channel.
Over-Range Error (Bit 14)
This bit is set (1) whenever a configured channel detects an over-range condition for the channel data. An over-range condition exists when the input value is equal to or above the specified upper limit of the particular sensor connected to that channel.
Channel Error (Bit 15)
This bit is set (1) whenever a configured channel detects an error in the configuration word, or an error has occurred while acquiring the ADC data value. If during the auto-calibration process, the module detects an out-of-range condition for the filter frequency selected for the channel, the channel error bit will be set. An out-of-range condition occurring during auto-calibration would be the result of an overly noisy environment, whereby the module cannot maintain accuracy specifications, thus flagging an error. The error bit is cleared when the error condition is resolved. The channel data word is still updated during a period of auto-calibration filter frequency tolerance errors, but accuracy may be degraded.
50 SLC 500™ Universal Analog Input Module
Chapter 5: Ladder Program Examples 51
Chapter 5
Programming Examples
Earlier chapters explained how the configuration word defines the way a channel operates. This chapter shows the programming required to enter the configuration word into the processor memory. It also provides you with segments of ladder logic specific to unique situations that might apply to your programming requirements. The example segments include:
• initial programming of the configuration word
• dynamic programming of the configuration word
• verifying channel configuration changes
• interfacing the universal module to a PID instruction
• monitoring channel status bit
Initial Programming
To enter data into the channel configuration word (O:e.0 through O:e.7) when the channel is disabled (bit 0 = 0), follow these steps. Refer to page 30 (Table 9) for specific configuration details.
Example - Configure eight channels of a universal module residing in slot 3 of a 1746 chassis. Configure each channel with the same parameters.
Figure 5.1 Channel configuration
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
10000011 01010011
Configure Channel For:
Channel Enable Bit ± 10.0 V Range Engineering Units x 10 Open Circuit Disabled Degrees C (N/A) 10 Hz Filter RTD Type (N/A) Auto-cal Disable Bit Channel Data Word
This example transfers configuration data and sets the channel enable bits of all eight channels with a single File Copy instruction.
52 SLC 500™ Universal Analog Input Module
Procedure
1. Using the memory map function, create integer file N10. Integer file N10 should contain eight elements (N10:0 through N10:7).
2. Using the APS software data monitor function, enter the configuration parameters for all eight universal channels into a source integer data file N10.
Figure 5.2 Data table for initial programming
address 15 data 0 address 15 data 0 N10:0 0000 0010 0010 0011 N10:3 0000 0010 0010 0011 N10:4 0000 0010 0010 0011 N10:5 0000 0010 0010 0011 N10:6 0000 0010 0010 0011 N10:7 0000 0010 0010 0011
Press a key or enter value N10:3/0 = 1 offline no forces binary data decimal addr File EXMPL
CHANGE
RADIX
F1
SPECIFY
ADDRESS
F5
NEXT
FILE
F7
PREV
FILE
F8
3. Program a rung in your ladder logic to copy the contents of integer file N10 to the eight consecutive output words of the universal module beginning with O:3.0.
Figure 5.3 Initial programming example
First Pass Bit
s:1
] [
15
Initialize Module
COP COPY FILE Source #N10:0
Length 8 Dest #O:3.0
On power up, bit S:1/15 is set for the first program scan, and integer file N10
is sent to the NI8u channel configuration words.
Dynamic Programming
Chapter 5: Ladder Program Examples 53
The following example explains how to change data in the channel configuration word when the channel is currently enabled.
Example - Execute a dynamic configuration change to channel 2 of the universal module located in slot 3 of a 1746 chassis. Change from monitoring a bipolar 10 V signal to monitoring the CJC sensors mounted on the terminal block. This gives a good indication of what the temperature is inside the control cabinet. Finally, set channel 2 back to the bipolar 10 V range.
Figure 5.4 Dynamic programming example
Program Listing
Rung 2:0
Rung 2:1
Rung 2:2
Rung 2:3
Set up all eight channels
s:1
] [
15
Set channel 2 to CJC
s:1 ] [
0
Set channel 2 back ±10V
I:1.0 ]/[
0
B3
{ OSR ]
0
B3 { OSR ] 1
COP COPY FILE Source #N10:0
Dest #O:3.0 Length 8
MOV MOVE Source N10:8
Dest O:3.2
MOV MOVE Source N10:2
Dest O:3.2
I END I
54 SLC 500™ Universal Analog Input Module
Figure 5.5 Data table for dynamic programming
address 15 data 0 address 15 data 0 N10:0 1000 0011 0101 0011 N10:8 1000 0000 0111 1111 N10:1 1000 0011 0101 0011 N10:2 1000 0011 0101 0011 N10:3 1000 0011 0101 0011 N10:4 1000 0011 0101 0011 N10:5 1000 0011 0101 0011 N10:6 1000 0011 0101 0011 N10:7 1000 0011 0101 0011
Important: While the module performs the configuration alteration, it does not monitor input device data change at any channel.
Verifying Channel Configuration Changes
When executing a dynamic channel configuration change, there will always be a delay from the time the ladder program makes the change to the time the NI8u gives you a data word using that new configuration information. Therefore, it is very important to verify that a dynamic channel configuration change took effect in the module, particularly if the channel being dynamically configured is used for control. The following example explains how to verify that channel configuration changes have taken effect.
Example - Execute a dynamic configuration change to channel 2 of the universal module located in slot 3 of a 1746 chassis, and set an internal “data valid” bit when the new configuration has taken effect. In this example the input image of the channel is selected to contain the channel status word.
Chapter 5: Ladder Program Examples 55
Figure 5.6 Programming for configuration changes
example
Rung 2:0
Rung 2:1
Rung 2:2
Rung 2:3
Set up all eight channels
s:1 ] [
15
Set channel 2 to CJC
I:1.0 ] [
0
Set channel 2 back to ±10V
I:1.0 ]/[
0
Check that the configuration written to channel two is being echoed back in channel two's status word.
EQU EQUAL Source A I:3.2
Source B O:3.2
B3 { OSR ] 0
B3 { OSR ] 1
COP COPY FILE Source #N10:0 Dest #O:3.0 Length 8
MOV MOVE Source N10:8
Dest O:3.2
MOV MOVE Source N10:2
Dest O:3.2
B3
( )
3
Rung 2:4
END I
I
Figure 5.7 Data table for configuration changes
Data Table
address 15 data 0 address 15 data 0
N10:0 1000 0011 0101 0011 N10:8 0000 0000 0111 1111 N10:1 1000 0011 0101 0011 N10:2 1000 0011 0101 0011 N10:3 1000 0011 0101 0011 N10:4 1000 0011 0101 0011 N10:5 1000 0011 0101 0011 N10:6 1000 0011 0101 0011 N10:7 1000 0011 0101 0011
56 SLC 500™ Universal Analog Input Module
Interfacing to the PID Instruction
The universal module was designed to interface directly to the SLC 5/02™ or later processor PID instruction without the need for an immediate scale operation.
Example - Use NI8u channel data as the process variable in the PID instruction.
1. Select scaled-for-PID as the data type in the channel configuration word.
2. Specify the input channel data word as the process variable for the PID instruction.
In this example, the value -32,617 is the numeric equivalent of configuration word N10:0 for channel 0. It is configured for a type K thermocouple, scaled-for-PID, zero the signal for an open circuit, 10 Hz, °C, channel enabled, to return the data word.
Figure 5.8 Programming for PID Control Example
Program Listing
Rung 2:0
Rung 2:1
Rung 2:2
Rung 2:3
First Pass Bit Initialize NI8u
s:1
] [
15
PID PID Control Block N11:0 Process Variable I:3.0 Control Variable N11:23 Control Block Length 23
The Rate and Offset parameters should be set per your application. The Dest will typically be an analog output channel. Refer to the APS User Manual or Analog I/O Modules User Manual for specific examples of the SLC instruction.
Channel 0 MOV MOVE Source N10:0
Dest O:3.0
SCL SCALE Source N11:23
Rate [/10000]
Offset
Dest
-32,617
0
END
I
I
address 15 data 0 address 15 data 0 N10:0 1000 0000 1001 0111
Monitoring Channel Status Bits
Chapter 5: Ladder Program Examples 57
Figure 5.9 Data table for PID Control
Data Table
The example shows how you could monitor the open circuit error bits of each channel and set an alarm in the processor if one of the inputs opens. An open circuit error can occur if one of the input signal wires gets cut or disconnected from the terminal block, or if the CJC sensors are not installed or are damaged.
Important: If a CJC input is not installed or is damaged, all thermocouple alarms are set, and their respective channel LEDs blink.
58 SLC 500™ Universal Analog Input Module
Figure 5.10 Monitoring channel status bits example
Program Listing
Rung 2:0
Rung 2:1
First Pass Bit Initialize NI8u
s:1 ] [ 15
Channel 0
Enable
I:3.0
] [
0
Channel 0
Open
I:3.0
] [
12
COP COPY FILE Source #N10:0 Dest #O:3.0 Length 8
Channel 0
Channel 0
Alarm O:2.0
( )
0
Rung 2:2
Rung 2:3
Rung 2:4
Rung 2:5
Rung 2:6
Rung 2:7
Channel 1
Enable
I:3.1
] [
0
Channel 2
Enable
I:3.2
] [
0
Channel 3
Enable
I:3.3
] [
0
Channel 4
Enable
I:3.4
] [
0
Channel 5
Enable
I:3.5
] [
0
Channel 6
Enable
I:3.6
] [
0
Channel 1
Open
I:3.1
] [
12
Channel 2
Open
I:3.2
] [
12
Channel 3
Open
I:3.3
] [
12
Channel 4
Open
I:3.4
] [
12
Channel 5
Open
I:3.5
] [
12
Channel 6
Open
I:3.6
] [
12
Channel 1
Alarm O:2.0
( )
1
Channel 2
Alarm O:2.0
( )
2
Channel 3
Alarm O:2.0
( )
3
Channel 4
Alarm O:2.0
( )
4
Channel 5
Alarm O:2.0
( )
5
Channel 6
Alarm O:2.0
( )
6
Rung 2:8
Channel 7
Enable
I:3.7
] [
0
Channel 7
Open
I:3.7
] [
12
Channel 7
Alarm O:2.0
( )
7
Figure 5.11 Data table for monitoring channel status
bits
Data Table
address 15 data 0 address 15 data 0 N10:0 0000 0000 1001 0111 N10:4 0000 0000 1001 0111 N10:1 0000 0000 1001 0111 N10:5 0000 0000 1001 0111 N10:2 0000 0000 1001 0111 N10:6 0000 0000 1001 0111 N10:3 0000 0000 1001 0111 N10:7 0000 0000 1001 0111
Chapter 5: Ladder Program Examples 59
This is an example of how to automatically switch between reading the channel status words and channel data words. Specifically, this example shows a very simple method of utilizing a timer to periodically switch between reading the channel status and data words.
The program utilizes a timer accumulator value to determine when to set up the configuration words, and when to read in the channel status and channel data information. The channel status information is copied from the I:2.0 to I:2.7 registers into registers N7:10 to N7:17. The channel data information is copied from I:2.0 to I:2.7 into registers N7:0 to N7:7. This allows sensor data and channel status information to be accessed at any time from these registers. However, when the module channels are configured to read sensor data, the channel status words (as reflected in N7:10 to N7:17) are not being dynamically updated, and vice-versa.
A longer interval between reading in the channel status information could be achieved through the utilization of a combination of counters and timers. If you are utilizing an SLC 5/03 or SLC 5/04 or later processor, the internal processor clock registers S:40 to S:42 could be utilized to determine the timing.
Rung 2:0
TON TIMER ON DELAY Timer T4:0 Timer Base 0.01 Preset 1001 Accum 0
(EN) (DN)
Timer T4:0 counts out a 10 second interval. Its accumulator indicates the progress it has made toward completion. The accumulator value shall be utilized to determine when to set the channel configuration word to send sensor data or to send status information.
A longer interval between transitions can be achieved using a combination of timers and counters.
60 SLC 500™ Universal Analog Input Module
Rung 2:1
This rung tests to see if T4:0.ACC is at a value between 800 and 950 counts. If so, the channel configuration words are defined (through the Fill File command) to send status information.
LIM LIMIT TEST Low Lim 800
Test T4:0.ACC
0
High Lim 950
FLL FILL FILE Source 151 Dest #O:2.0 Length 8
Rung 2:2
This rung executes a Copy File command to move the channel status word (as enabled in the previous rung) into registers N7:10 through N7:17 for all channels.
Though the module is quick about switching from sensor data to status information, it is a good idea to give the module a little time to switch modes. That is why this example uses a half second period in time between when the channel is set-up to send the status word and when the status word is read into the N7 table.
LIM LIMIT TEST Low Lim 950
Test T4:0.ACC
0
High Lim 1000
COP COPY FILE Source #I:2.0 Dest #N7:10 Length 8
Chapter 5: Ladder Program Examples 61
Rung 2:3
This rung will copy the channel sensor data into registers N7:0 through N7:7, about 2 seconds after the configuration word has been changed to send sensor data.
Timing is important here. Because the channels are multiplexed, it can take the module some amount of time to update the channel input word with sensor data it has been sending channel status information. That amount of time is determined by the module update time and the worst case autocalibration time that could occur based on the filter frequencies and input types selected.
LIM LIMIT TEST Low Lim 200
Test T4:0.ACC
0
High Lim 750
COP COPY FILE Source #I:2.0 Dest #N7:0 Length 8
Rung 2:4
This rung will set the channel configuration words for sending sensor data, each time the timer completes a cycle. It also resets the timer.
T4:0 ] [ DN
FLL FILL FILE Source -32617 Dest #O2:0 Length 8
T4:0 (RES)
Rung 2:5
|END|
62 SLC 500™ Universal Analog Input Module
Chapter 6
Testing Your Module
This chapter describes troubleshooting with channel-status and module­status LEDs. It explains the types of conditions that might cause the module to flag an error, and suggests what corrective action you could take. Topics include:
• module and channel diagnostics
• LED indicators
• Interpreting I/O error codes
• troubleshooting flowchart
Module and Channel Diagnostics
The module operates at two levels:
• module level
• channel level
Module level operation includes functions such as power-up, configuration, and communication with the SLC processor. ON indicates the module is OK. OFF indicates a fault.
Channel level operation includes functions such as data conversion and open-circuit detection. ON indicates the channel is OK. Blinking indicates a fault.
The module performs internal diagnostics at both levels, and immediately indicates detected error conditions with either of its status LEDs. When a status LED is continuously ON, the status is OK.
Module Diagnostics at Power-up
At module power-up, the module performs a series of internal diagnostic tests. If the module detects a failure, its module status LED remains off.
Channel Diagnostics
When a channel is enabled, the module checks for a valid configuration. Then on each scan of its inputs, the module checks for out-of-range and open-circuit fault conditions of its inputs including the CJC input.
When the module detects a failure of any channel diagnostic test, it causes the channel status LED to blink and sets the corresponding channel fault
64 SLC 500™ Universal Analog Input Module
bit (bits 12-15 of the channel status word). Channel fault bits and LEDs are self-clearing when fault conditions are corrected.
Important: If you clear the channel enable bit, channel status bits are reset.
LED Indicators
The module has nine LEDs:
• eight channel-status LEDs, numbered to correspond with each channel
• one module-status LED
INPUT
Status
014
236
5
7
LEDs for Channels 0-7
Channel
LED for Module Status
Module Universal Analog
LED Troubleshooting Tables
Table 6.1 Module-status LED
If Module Status LED is: Then: Take this Corrective Action:
On The module is OK. No action required.
Of f The module is turned off, Cycle power. If the condition persists,
or it detected a module call your local distributor or Spectrum fault. Controls for assistance.
Table 6.2 Module-status and Channel-status LED
If Module Status And Channel Then: Take this Corrective Action: LED is: Status LED is:
On The channel No action required.
is enabled.
Blinking The module Examine error bits in status word
detected: if bit 12=1, the input has an open circuit
On open-circuit condition if bit 13=1, the input value is under range
under-range condition if bit 14=1, the input value is over range over-range condition if bit 15=1, the channel has a diagnostic channel error or channel error
Off The module is in No action is required.
power up, or the channel is disabled.
Chapter 6: Testing Your Module 65
Channel-status LEDs (Green)
The channel-status LED operates with status bits in the channel status word to indicate the following faults detected by the module:
• invalid channel configuration
• an open-circuit input
• out-of-range errors
• selected filter frequency data acquisition or auto-calibration errors
When the module detects any of the following fault conditions, it causes the channel-status LED to blink and sets the corresponding fault bit in the channel status word. Channel fault bits (bits 12-15) and channel-status LEDs are self-clearing when fault conditions are corrected.
Open-circuit Detection (Bit 12)
If open-circuit is enabled for an applicable input channel, the module tests the channel for an open-circuit condition each time it scans its input. Open-circuit detection is always performed for the CJC inputs. Open circuit does not apply to ±2V, 0-5V, 1-5V, ±10V, 0-10V, or 0-20mA ranges. Possible causes of an open circuit include:
• broken thermocouple, RTD or CJC sensor
• thermocouple, RTD or CJC sensor wire cut or disconnected
• millivolt, volt or milliamp input wire cut or disconnected
• less than 3 ohms has been detected on an RTD input.
Out-of-Range Detection (Bit 13 for under range, bit 14 for over range)
The module tests all enabled channels for an out-of-range condition each time it scans its inputs. Possible causes of an out-of-range condition include:
• the temperature is too hot or too cold for the thermocouple or RTD being used
• a type B thermocouple may be registering a °F value in EU x1 beyond the range allowed by the SLC processor (beyond 32,767) for the data word
• a CJC sensor may be damaged or the temperature being detected by the CJC may be outside the CJC sensor range limits
• the millivolt, Volt, or milliamp input is outside of its selected input range
66 SLC 500™ Universal Analog Input Module
Channel Error (Bit 15)
The module sets this fault bit when it detects any of the following:
Configuration erorrs:
- configuration bits Data Format definition, invalid Input Types for channels 0 through 3: 10010 - 11101
- configuration bits Data Format definition of Engineering Units x 1 for Input Types of ±500mV, 0-5V, 1-5V, 0-10V, ±10V, 0-20mA
- configuration bits where Open Circuit is enabled with Input types of 0­5V, 1-5V, 0-10V, ±10V, or 0-20mA
- invalid data acquisition of an input channel
- the filter frequency selected for the valid channel currently fails autocalibration range checks
Module Status LED (Green)
Interpreting I/O Error Codes
The module-status LED indicates when the module detects a nonrecoverable fault at power up or during operation. For this type of fault, the module:
• no longer communicates with the SLC processor
• disables all channels
• clears all data and status words
A module failure is non-recoverable and requires the assistance of your local distributor or Spectrum Controls.
I/O error codes appear in word S:6 of the SLC processor status file. The first two digits of the error code identify the slot (in hexadecimal) with the error. The last two digits identify the I/O error code (in hexadecimal).
The error codes that apply to your module include (in hexadecimal):
• 50–5E
• 71 (watchdog error)
• 90–94
For a description of the error codes, refer to the Allen-Bradley Advanced Programming Software (APS) Reference Manual, Allen-Bradley publication 1746-6.11.
Verifying With Test Instrumentation
Chapter 6: Testing Your Module 67
The 1746sc-NI8u has multiplexed channel inputs which switch in order to read an input channel. The settling time is 3ms. Caution must be used when testing the module with a test instrument, because the instrument may require a settling time much greater than 3 ms. Errors will result in the test instrument sourcing if its settling time requirement is not met. Contact the instrumentation manufacturer for settling time requirements before using the instrument to test your module.
68 SLC 500™ Universal Analog Input Module
Figure 6.1 Troubleshooting Flowchart
Check LEDs
on module.
Module
Status LED(s)
off.
Module fault
condition.
Check to see
that module is
seated properly
in chassis.
Cycle power.
Is problem
corrected?
No
Module
Status LED
on.
Normal module
operation.
End
Ye s
End
Status LED(s)
Fault
condition.
Are
faulted channel(s)
configured for mV or
thermocouple
input?
Thermocouple
Is more than one
LED blinking?
Ye s
CJC fault
has probably
occurred
Check that wiring is secure
at both CJCs and that the
temperature within the enclosure is in the range limits of the CJC sensor.
(Refer to Chapter One.)
Ye s
Is problem corrected?
No
RTD or resistance
Check channel
status word
bits 1215.
Channel
blinking.
mV, mA,
No
Bit 15
set (1)
Bit 14
set (1)
Bit 13
set (1)
Channel
Status LED(s)
off.
Channel is
not enabled.
Enable channel if desired by setting
channel config. word (bit 0 = 1).
Retry.
Channel error. Check
configuration word
for a valid input type
configuration and insure
bit 14 is set to zero.
Retry.
Over-range condition exists.
The input signal is greater
than the high scale limit for
the channel or the CJC
connections. Correct and
Retry.
Under-range condition exists.
The input signal is less than
the low scale limit for the
channel or the CJC
connections. Correct and
Retry.
Channel
Status LED(s)
on.
Channel is
enabled and
working.
End
Ye s
Is problem corrected?
No
Contact you local
distributor or
Spectrum
Controls.
Contact you local
distributor or
Spectrum
Controls.
Bit 12
set (1)
An open-circuit condition is
present. Check channel and
CJC wiring for open or
loose connections. Check
for short circuited RTD
connections. Retry.
Contact you local
distributor or
Spectrum
Controls.
Chapter 7: Maintaining Your Module And Ensuring Safety 69
Chapter 7
Maintaining Your Module And Ensuring Safety
Read this chapter to familiarize yourself with:
• preventive maintenance
• safety considerations
The National Fire Protection Association (NFPA) recommends maintenance procedures for electrical equipment. Refer to article 70B of the NFPA for general safety-related work practices.
Preventive Maintenance
Safety Considerations
The printed circuit boards of your module must be protected from dirt, oil, moisture, and other airborne contaminants. To protect these boards, install the SLC 500 system in an enclosure suitable for its operating environment. Keep the interior of the enclosure clean, and whenever possible, keep the enclosure door closed.
Also, regularly inspect the terminal connections for tightness. Loose connections may cause a malfunctioning of the SLC system or damage to the components.
WARNING
!
POSSIBLE LOOSE CONNECTIONS
Before inspecting connections, always ensure that incoming power is OFF.
Failure to observe this precaution can cause personal injury and equipment damage.
Safety is always the most important consideration. Actively think about the safety of yourself and others, as well as the condition of your equipment. The following are some things to consider:
Indicator Lights – When the module status LED on your module is illuminated, your module is receiving power.
Activating Devices When Troubleshooting – Never reach into a machine to activate a device; the machine may move unexpectedly. Use a wooden stick.
70 SLC 500™ Universal Analog Input Module
Standing Clear Of Machinery – When troubleshooting a problem with any SLC 500 system, have all personnel remain clear of machinery. The problem may be intermittent, and the machine may move unexpectedly. Have someone ready to operate an emergency stop switch.
CAUTION
!
Safety Circuits – Circuits installed on machinery for safety reasons (like over-travel limit switches, stop push-buttons, and interlocks) should always be hard-wired to the master control relay. These circuits should also be wired in series so that when any one circuit opens, the master control relay is de-energized, thereby removing power. Never modify these circuits to defeat their function. Serious injury or equipment damage may result.
POSSIBLE EQUIPMENT OPERATION
Never reach into a machine to actuate a switch. Also, remove all electrical power at the main power disconnect switches before checking electrical connections or inputs/ outputs causing machine motion.
Failure to observe these precautions can cause personal injury or equipment damage.
WARNING
!
EXPLOSION HAZARD
SUBSTITUTION OF COMPONENTS MAY IMPAIR SUITABILITY FOR CLASSI DIVISION2.
WARNING
!
EXPLOSION HAZARD
DO NOT DISCONNECT EQUIPMENT UNLESS POWER HAS BEEN SWITCHED OFF OR THE AREA IS KNOWN TO BE NON-HAZARDOUS.
NONO
TE:TE:
NO
TE: THIS EQUIPMENT IS SUITABLE FOR USE IN
NONO
TE:TE: CLASSI, DIVISION 2, GROUPS A, B, C, AND D OR NON­HAZARDOUS LOCATIONS ONLY.
Chapter 7: Maintaining Your Module And Ensuring Safety 71
WARNING
!
EXPLOSION HAZARD
!
WHEN IN HAZARDOUS LOCATIONS, TURN OFF POWER BEFORE REPLACING OR WIRING MODULES.
WARNING
!
Refer to your system’s Installation & Operation Manual for more information.
THIS DEVICE IS INTENDED TO ONLY BE USED WITH THE ALLEN-BRADLEY SLC500 SYSTEMS.
72 SLC 500™ Universal Analog Input Module
Electrical Specifications
Appendix A
Module Specifications
This appendix lists the specifications for the 1746sc-NI8u Universal analog Input Module.
Backplane Current Consumption 120 mA at 5 VDC
100 mA at 24 VDC
Backplane Power Consumption 3.00W maximum (0.6W @ 5 VDC, 2.4W @ 24 VDC)
Number of Channels 8 (backplane and channel-to-channel isolated)
I/O Chassis Location Any I/O module slot except 0
A/D Conversion Method Sigma-Delta Modulation
Input Filtering Low pass digital filter with programmable notch (filter)
frequencies
Normal Mode Rejection (between 100 dB at 50 Hz [+] input and [-] input) 100 dB at 60 Hz
Common Mode Rejection (between 100 dB at 50/60 Hz inputs and chassis ground)
Input Filter Cut-Off Frequencies
2.6 Hz at 10 Hz filter frequency
13.1 Hz at 50 Hz filter frequency
15.72 Hz at 60 Hz filter frequency
65.5 Hz at 250 Hz filter frequency
Calibration Module autocalibrates at power-up and
approximately every two minutes afterwards*
Input Overvoltage Protection ±14.5 VDC continuous
250W pulsed for 1 msec.
Input Overcurrent Protection 28 mA continuous
40 mA, 1mS pulsed, 10% duty cycle maximum
Isolation 500 VDC continuous between inputs and chassis
ground and between inputs and backplane.
12.5 VDC continuous between channels of TC / V / i 0 VDC between channels of RTD
* = See page 28 for detailed explanation of auto-calibration.
74 SLC 500™ Universal Analog Input Module
Physical Specifications
LED Indicators 9 green status indicators, one for each of 8
Module ID Code 3500
Recommended Cable: for thermocouple inputs... Shielded twisted pair thermocouple extension wiren
for mV, V or mA inputs Belden 8761 or equivalent
for RTD inputs shielded Belden #9501, #9533, #83503o
Maximum Wire Size One 16 AWG wire or two 22 AWG wires per terminal
n
Refer to the thermocouple manufacturer for the correct extension wire.
o
Refer to the RTD manufacturer and Chapter 1 of this user’s manual.
EnvironmentalSpecifications
Operating Temperature 0°C to 60°C (32°F to 140°F)
channels and one for module status
Input Specifications
Storage Temperature -40°C to 85°C (-40°F to 185°F)
Relative Humidity 5% to 95% (without condensation)
Certification UL & CUL approved
Hazardous Environment Class1 Division 2 Hazardous Environment Classification Groups A, B, C, D
EMC CE compliant
Thermocouple Type J -210°C to 760°C (-346°F to 1400°F) Thermocouple Type K -270°C to 1370°C (-454°F to 2498°F) Thermocouple Type T -270°C to 400°C (-454°F to 752°F) Thermocouple Type E -270°C to 1000°C (-454°F to 1832°F)
Type of Input (Selectable) Thermocouple Type R 0°C to 1768°C (32°F to 3214°F)
Thermocouple Type S 0°C to 1768°C (32°F to 3214°F) Thermocouple Type B 300°C to 1820°C (572°F to 3308°F) Thermocouple Type N 0°C to 1300°C (32°F to 2372°F) Thermocouple Type C 0°C to 2315°C (32°F to 4199°F)
Millivolt (-50 mVdc to +50 mVdc) Millivolt (-100 mVdc to +100 mVdc) Millivolt (±500mV, ±2V, 0-5V, 1-5V, 0-10V, ±10V)
Current (4 to 20mA) Current ( 0 to 20mA)
RTD Pt 385 -200°C to 850°C -328°F to 1562°F
(100, 500Ω, 1000Ω)
RTD Pt 385 -200°C to 750°C -328°F to 1382°F
(200Ω)
RTD Pt 3916 -200°C to 630°C -328°F to 1166°F
(100Ω, 200, 500Ω, 1000Ω) RTD 10Cu 426 -100°C to 260°C -148°F to 500°F RTD 120Ni 618 -100°C to 260°C -148°F to 500°F RTD 120Ni 672 -80°C to 260°C -112°F to 500°F Resistance (0 to 3000Ω)
Appendix A: Module Specifications 75
RTD Conversion JIS C 1602-1997 for Pt 385
JIS C 1604-1989 for Pt 3916
SAMA RC21-4-1966 for the 10Cu 426 RTD DIN 43760 Sept. 1987 for the 120 Ni 618 RTD MINCO Application Aid #18 May 1990 for the 120Ω Ni 672 RTD
Thermocouple NIST ITS-90 standard Linearization
Channel Multiplexing 3 mS Settling Time
RTD Current Source 200µA, one for each RTD channel
Cold Junction Accuracy ±1.72°C, -25°C to +105° Compensation On board CJC Sensor Required, Analog Devices AD592CN
Input Impedence Greater than 10M > Ohm Voltage / Thermocouple / RTD
< 250 Ω current
Temperature Scale °C of °F and 0.1°C or 0.1°F (Selectable)
DC Millivolt Scale 0.1 mV, 0.01 mV, or 0.001 mV (Selectable) Depending on input type
Milliamp Scale .01 mA or .001mA (Selectable)
Open Circuit Detection Upscale, Downscale, Zero, or Disabled (Selectable) Does not apply to 5 or 10V range, or 0-20mA input type
Time to Detect One module update time Open Circuit
Input Step Response 0 to 95% in 300 msec (10 Hz)
Display Resolution See Channel Data Word Resolution table in Chapter 4
Overall Module Accuracy See Module Accuracy Tables below @ 25°C (77°F)
Overall Module Accuracy See Module Accuracy Tables below (0°C to 60°C, 32°F to 140°F)
Overall Module Drift See Module Accuracy Tables below
Module Update Time Dependent upon enabled channels (see Update Time, Chap 3)
Channel Turn-Off Time Up to one module update time
Overall Accuracy
The accuracy of the module is determined by many aspects of the hardware and software functionality of the module. The following attempts to explain what the user can expect in terms of accuracy based on the thermocouple, RTD, resistance, and millivolt, volt, and milliamp inputs for the NI8u module.
76 SLC 500™ Universal Analog Input Module
The accuracies specified as follows include errors due to the cold junction compensation for thermocouples, current source errors for RTDs, and hardware and software errors associated with the system, which depends upon input path. RTD accuracies do not include errors due to lead resistance. The hardware and software errors include calibration of the system, and non-linearity of the ADC. For the sake of the calculations the resolution of the ADC was assumed to be at least 16 bits (use of the 10Hz, 50Hz, and 60Hz filter frequencies). Note: The 250Hz frequency should not be applied to thermocouple or RTD inputs if accuracy is a concern.
Thermocouple
The following table provides the maximum error for each thermocouple type when the 10Hz, 50Hz, or 60Hz filters are used and the module is operating at 25°C and was calibrated at 25°C. Inaccuracies in the cold junction compensation sensors are not included.
Thermocouple Max. Error
Type 25°C
J ±0.6°C K -225°C to 1370°C ±1.0°C K -270°C to -225°C ±7.5°C T -230°C to +400°C ±1.0°C T -270°C to -230°C ±5.4°C E -210°C to +1000°C ±0.5°C E -270°C to -210°C ±4.2°C R ±1.7°C S ±1.7°C B ±3.0°C N ±0.4°C C ±1.8°C
The following table provides the maximum error for each thermocouple type when the 10Hz, 50Hz, or 60Hz filters are used and the module is operating at 0°C to 60°C and was calibrated at that temperature. Inaccuracies in the cold junction compensation sensors are not included.
Thermocouple Max. Error
Type 0°C to 60°C
J ±0.9°C K -225°C to 1370°C ±1.5°C K -270°C to -225°C ±10.0°C T -230°C to +400°C ±1.5°C T -270°C to -230°C ±7.0°C E -210°C to +1000°C ±0.8°C E -270°C to -210°C ±6.3°C R ±2.6°C S ±2.6°C B ±4.5°C N ±0.6°C C ±3.5°C
The diagrams that follow for each thermocouple type, give data for a sample module over the input range of the thermocouple, over temperature. Thermocouples are usually parabolic in their µV to degrees C curves. Normally, at the ends of any given thermocouple range, the ratio of change in temperature increases as a result of a change in voltage. In other words, at the ends, a smaller change in voltage results in a larger change in degrees.
0.1
0.05
0
-0.05
-0.1
-0.15
-0.2
Degrees C Deviation
-0.25
Appendix A: Module Specifications 77
Thermocouple Type J, Exa mple Deviations
Ch 2 Delta, 25C
Ch 2 Delta, 0C
Ch 2 Delta, 60C
-0.3
-0.35
-210 -110 - 10 90 190 290 390 490 590 690 790
Degrees C TC Input
Thermocouple Type K, Example Deviations (Low Range )
3
2.5
2
1.5
1
0.5
Degrees C Deviation
0
-0.5
-270 -260 -250 -240 -230 -220 -210 -200
Degrees C TC Input
Ch 2 Delta, 25C
Ch 2 Delta, 0C
Ch 2 Delta, 60C
78 SLC 500™ Universal Analog Input Module
Thermocouple Type K, Example Deviations (High Range)
0.3
0.2
0.1
0
-0.1
Degrees C Deviation
-0.2
-0.3
-200 0 200 400 600 800 1000 1200 1400
Degrees C TC Input
Ch 2 Delta, 25C
Ch 2 Delta, 0C
Ch 2 Delta, 60C
Thermocouple Type T, Example Deviations (Low Range)
0.5
0
-0.5
-1
Degrees C Deviation
-1.5
-2
-270 -260 -250 -240 -230 -220 -210 -200
Degrees C TC Input
Ch 2, Delta, 25 C
Ch 2 Delta, 0C
Ch 2 Delta, 60C
0.05
-0.05
Appendix A: Module Specifications 79
Thermocouple Type T, Example Deviations (High Range)
0
-0.1
-0.15
-0.2
Degrees C Deviation
-0.25
-0.3
-200 -100 0 100 200 300 400
Degrees C TC Input
Thermocouple Type E, Example Deviations
0.2
Ch 2, Delta, 25 C
Ch 2 Delta, 0C
Ch 2 Delta, 60C
0
-0.2
-0.4
-0.6
-0.8
Degrees C Deviation
-1
-270 -170 -70 30 130 230 330 430 530 630 730 830 930 1030
Degrees C TC Input
Ch 2 Delta, 25C
Ch 2 Delta, 0C
Ch 2 Delta, 60C
80 SLC 500™ Universal Analog Input Module
Thermocouple Type R, Example Deviations
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
-0.7
Degrees C Deviation
-0.8
-0.9
-1
-1.1
0 200 400 600 800 1000 1200 1400 1600 1800
Degrees C TC Input
Ch 2 Delta, 25C
Ch 2 Delta, 0C
Ch 2 Delta, 60C
Ther mocouple Type S, Exa mple Deviations
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
-0.7
-0.8
Degrees C Deviation
-0.9
-1
-1.1
0 200 400 600 800 1000 1200 1400 1600 1800
Degrees C TC Input
Ch 2 De lta , 25 C
Ch 2 De lta , 0C
Ch 2 De lta , 60 C
0.5
Appendix A: Module Specifications 81
Thermocouple Type B, Example Deviations
0
-0.5
-1
Degrees C Deviation
-1.5
-2
300 500 700 900 1100 1300 1500 1700 1900
Degrees C TC Input
Thermocouple Type N, Exa mple Deviations
0.1
Ch 2 Delta, 25C
Ch 2 Delta, 0C
Ch 2 Delta, 60C
0
-0.1
-0.2
Degrees C Deviation
-0.3
-0.4
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300
Degr ee s C TC Input
Ch 2 De lt a, 2 5C
Ch 2 De lt a, 0 C
Ch 2 De lt a, 6 0C
82 SLC 500™ Universal Analog Input Module
Thermocouple C Type, Example Varia tions
0.5
0.4
0.3
0.2
0.1
0
-0.1
-0.2
Degrees C Variation
-0.3
-0.4
-0.5
0 463 926 1389 1852 2315
Degrees C TC Input
Ch 2 Delta, 25C
Ch 2 Delta, 0C
CH 2 De lt a, 60C
RTD and Resistance
The following table provides the maximum error for each RTD and resistance type when the 10 Hz, 50 Hz, and 60 Hz filters are used and the module is operating at 25°C and was calibrated at 25°C. Errors due to lead wire resistance mismatches are not included.
Input Max. Error Type 25°C
100 Pt 385 ±1.0°C 200 Pt 385 ±0.7°C
500 Pt 385 ±0.6°C 1000 Pt 385 ±0.5°C 100 Pt 3916 ±0.9°C 200 Pt 3916 ±0.6°C 500 Pt 3916 ±0.5°C
1000 Pt 3916 ±0.4°C
10Ω Cu 426 ±3.0°C 120 Ni 618 ±0.4°C 120 Ni 672 ±0.4°C
3000 Resistance ±2.0
Appendix A: Module Specifications 83
The following table provides the maximum error for each RTD and resistance type when the 10 Hz, 50 Hz, and 60 Hz filters are used and the module is operating at 0°C to 60°C and was at that temperature. Errors due to lead wire resistance mismatches are not included.
Input Max. Error
Type 0°C to 60°C
100 Pt 385 ±3.3°C 200 Pt 385 ±2.8°C 500 Pt 385 ±3.0°C
1000 Pt 385 ±2.9°C 100 Pt 3916 ±2.7°C 200 Pt 3916 ±2.4°C 500 Pt 3916 ±2.3°C
1000 Pt 3916 ±2.2°C
10Ω Cu 426 ±4.5°C 120 Ni 618 ±0.8°C 120 Ni 672 ±0.8°C
3000 Resistance ±7.0
The diagrams that follow provide data from a sample module for a given RTD type over a range of inputs, over temperature.
100Ω Pt 385 RTD, Example Deviations
0.1 0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
-0.7
-0.8
-0.9
-1
Degrees C Deviation
-1.1
-1.2
-1.3
-1.4
-200 -100 0 100 200 300 400 500 600 700 800 900
Degrees C RTD Input
Ch 7 Delta, 25C
Ch 7 Delta, 0C
Ch 7 Delta, 60C
84 SLC 500™ Universal Analog Input Module
200Ω Pt 385 RTD, Example Deviations
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
Degrees C Deviation
-0.6
-0.7
-0.8
-200 -100 0 100 200 300 400 500 600 700 800
Degrees C RTD Input
Ch 7 Delta, 25C
Ch 7 Delta, 0C
Ch 7 Delta, 60C
500Ω Pt 385 RTD, Example Deviations
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
Degrees C Deviation
-0.7
-0.8
-0.9
-200 -100 0 100 200 300 400 500 600 700 800 900
Degrees C RTD Input
Ch 7 Delta, 25C
Ch 7 Delta, 0C
Ch 7 Delta, 60C
Appendix A: Module Specifications 85
1000Ω Pt 385 RTD, Example Deviations
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
-0.7
Degrees C Deviation
-0.8
-0.9
-1
-1.1
-200 - 100 0 100 200 300 400 500 600 700 800 900
Degrees C RTD Input
Ch 7 Delta, 25C
Ch 7 Delta, 0C
CH 7 De lt a, 60C
100Ω Pt 3916 RTD, Example Deviations
0.4
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
Degrees C Deviation
-0.7
-0.8
-0.9
-1
-200 -100 0 100 200 300 400 500 600 700
Degrees C RTD Input
Ch 7 Delta, 25C
Ch 7 Delta, 0C
Ch 7 Delta, 60C
86 SLC 500™ Universal Analog Input Module
200Ω Pt 3916 RTD, Example Deviations
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
Degrees C Deviation
-0.6
-0.7
-0.8
-200 -100 0 100 200 300 400 500 600 700
Degrees C RTD Input
Ch 7 Delta, 25C
Ch 7 Delta, 0C
Ch 7 Delta, 60C
500Ω Pt 3916 RTD, Example Deviations
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
Degrees C Deviation
-0.6
-0.7
-0.8
-200 -100 0 100 200 300 400 500 600 700
Degrees C RTD Input
Ch 7 Delta, 25C
Ch 7 Delta, 0C
Ch 7 Delta, 60C
Appendix A: Module Specifications 87
1000Ω Pt 3916 RTD, Example Deviations
0.25
0
-0.25
Degrees C Deviation
-0.5
-0.75
-200 -100 0 100 200 300 400 500 600 700
Degrees C RTD Input
Ch 7 Delta, 25C
Ch 7 Delta, 60C
Ch 7 Delta, 0C
10Ω Cu 426 RTD, Example Deviations
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
-0.7
-0.8
Degrees C Deviation
-0.9
-1
-1.1
-1.2
-100 -50 0 50 100 150 200 250 300
Degrees C RTD Input
Ch 7 Delta, 25C
Ch 7 Delta, 60C
Ch 7 Delta, 0C
88 SLC 500™ Universal Analog Input Module
120Ω Ni 618 RTD, Example Deviations
0.1
0
-0.1
Degrees C Deviation
-0.2
-0.3
-100 0 100 200 300
Degrees C RTD Input
Ch 7 Delta, 25C
Ch 7 Delta, 60C
CH 7 De lt a, 0C
120Ω Ni 672 RTD, Example Deviations
0.1
0
-0.1
-0.2
Degrees C Deviation
-0.3
-0.4
-80 -40 0 40 80 120 160 200 240 280
Degrees C RTD Input
Ch 7 Delta, 25C
Ch 7 Delta, 60C
Ch 7 Delta, 0C
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