Tektronix M3000,M4000 Series Computer To Analog Output Interfaces User's Manual 64990A User manual

M3000/M4000 Series

User’s Manual

A GREATER MEASURE OF CONFIDENCE

WARRANTY

Hardware

Keithley Instruments, Inc. warrants that, for a period of one (1) year from the date of shipment (3 years for Models 2000, 2001, 2002, 2010 and 2700), the Keithley Hardware product will be free from defects in materials or workmanship. This warranty will be honored provided the defect has not been caused by use of the Keithley Hardware not in accordance with the instructions for the product. This warranty shall be null and void upon: (1) any modiﬁcation of Keithley Hardware that is made by other than Keithley and not approved in writing by Keithley or (2) operation of the Keithley Hardware outside of the environmental speciﬁcations therefore.

Upon receiving notiﬁcation of a defect in the Keithley Hardware during the warranty period, Keithley will, at its option, either repair or replace such Keithley Hardware. During the ﬁrst ninety days of the warranty period, Keithley will, at its option, supply the necessary on site labor to return the product to the condition prior to the notiﬁcation of a defect. Failure to notify Keithley of a defect during the warranty shall relieve Keithley of its obligations and liabilities under this warranty.

Other Hardware

The portion of the product that is not manufactured by Keithley (Other Hardware) shall not be covered by this warranty, and Keithley shall have no duty of obligation to enforce any manufacturers' warranties on behalf of the customer. On those other manufacturers’ products that Keithley purchases for resale, Keithley shall have no duty of obligation to enforce any manufacturers’ warranties on behalf of the customer.

Software

Keithley warrants that for a period of one (1) year from date of shipment, the Keithley produced portion of the software or ﬁrmware (Keithley Software) will conform in all material respects with the published speciﬁcations provided such Keithley Software is used on the product for which it is intended and otherwise in accordance with the instructions therefore. Keithley does not warrant that operation of the Keithley Software will be uninterrupted or error-free and/ or that the Keithley Software will be adequate for the customer's intended application and/or use. This warranty shall be null and void upon any modiﬁcation of the Keithley Software that is made by other than Keithley and not approved in writing by Keithley.

If Keithley receives notiﬁcation of a Keithley Software nonconformity that is covered by this warranty during the warranty period, Keithley will review the conditions described in such notice. Such notice must state the published speciﬁcation(s) to which the Keithley Software fails to conform and the manner in which the Keithley Software fails to conform to such published speciﬁcation(s) with sufﬁcient speciﬁcity to permit Keithley to correct such nonconformity. If Keithley determines that the Keithley Software does not conform with the published speciﬁcations, Keithley will, at its option, provide either the programming services necessary to correct such nonconformity or develop a program change to bypass such nonconformity in the Keithley Software. Failure to notify Keithley of a nonconformity during the warranty shall relieve Keithley of its obligations and liabilities under this warranty.

Other Software

OEM software that is not produced by Keithley (Other Software) shall not be covered by this warranty, and Keithley shall have no duty or obligation to enforce any OEM's warranties on behalf of the customer.

Other Items

Keithley warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable batteries, diskettes, and documentation.

Items not Covered under Warranty

This warranty does not apply to fuses, non-rechargeable batteries, damage from battery leakage, or problems arising from normal wear or failure to follow instructions.

Limitation of Warranty

This warranty does not apply to defects resulting from product modiﬁcation made by Purchaser without Keithley's express written consent, or by misuse of any product or part.

Disclaimer of Warranties

EXCEPT FOR THE EXPRESS WARRANTIES ABOVE KEITHLEY DISCLAIMS ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION, ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. KEITHLEY DISCLAIMS ALL WARRANTIES WITH RESPECT TO THE OTHER HARDWARE AND OTHER SOFTWARE.

Limitation of Liability

KEITHLEY INSTRUMENTS SHALL IN NO EVENT, REGARDLESS OF CAUSE, ASSUME RESPONSIBILITY FOR OR BE LIABLE FOR: (1) ECONOMICAL, INCIDENTAL, CONSEQUENTIAL, INDIRECT, SPECIAL, PUNITIVE OR EXEMPLARY DAMAGES, WHETHER CLAIMED UNDER CONTRACT, TORT OR ANY OTHER LEGAL THEORY, (2) LOSS OF OR DAMAGE TO THE CUSTOMER'S DATA OR PROGRAMMING, OR (3) PENALTIES OR PENALTY CLAUSES OF ANY DESCRIPTION OR INDEMNIFICATION OF THE CUSTOMER OR OTHERS FOR COSTS, DAMAGES, OR EXPENSES RELATED TO THE GOODS OR SERVICES PROVIDED UNDER THIS WARRANTY.

Keithley Instruments, Inc. 28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • Fax: 440-248-6168

1-888-KEITHLEY (534-8453) • www.keithley.com

Sales Ofﬁces:BELGIUM: Bergensesteenweg 709 • B-1600 Sint-Pieters-Leeuw • 02-363 00 40 • Fax: 02/363 00 64

CHINA: Yuan Chen Xin Building, Room 705 • 12 Yumin Road, Dewai, Madian • Beijing 100029 • 8610-6202-2886 • Fax: 8610-6202-2892 FINLAND: Tietäjäntie 2 • 02130 Espoo • Phone: 09-54 75 08 10 • Fax: 09-25 10 51 00 FRANCE: 3, allée des Garays • 91127 Palaiseau Cédex • 01-64 53 20 20 • Fax: 01-60 11 77 26 GERMANY: Landsberger Strasse 65 • 82110 Germering • 089/84 93 07-40 • Fax: 089/84 93 07-34 GREAT BRITAIN: Unit 2 Commerce Park, Brunel Road • Theale • Berkshire RG7 4AB • 0118 929 7500 • Fax: 0118 929 7519 INDIA: Flat 2B, Willocrissa • 14, Rest House Crescent • Bangalore 560 001 • 91-80-509-1320/21 • Fax: 91-80-509-1322 ITALY: Viale San Gimignano, 38 • 20146 Milano • 02-48 39 16 01 • Fax: 02-48 30 22 74 JAPAN: New Pier Takeshiba North Tower 13F • 11-1, Kaigan 1-chome • Minato-ku, Tokyo 105-0022 • 81-3-5733-7555 • Fax: 81-3-5733-7556 KOREA: 2FL., URI Building • 2-14 Yangjae-Dong • Seocho-Gu, Seoul 137-888 • 82-2-574-7778 • Fax: 82-2-574-7838 NETHERLANDS: Postbus 559 • 4200 AN Gorinchem • 0183-635333 • Fax: 0183-630821 SWEDEN: c/o Regus Business Centre • Frosundaviks Allé 15, 4tr • 169 70 Solna • 08-509 04 679 • Fax: 08-655 26 10 SWITZERLAND: Kriesbachstrasse 4 • 8600 Dübendorf • 01-821 94 44 • Fax: 01-820 30 81 TAIWAN: 1FL., 85 Po Ai Street • Hsinchu, Taiwan, R.O.C. • 886-3-572-9077• Fax: 886-3-572-9031

4/02

M3OOU/M4UUU

SERIES

USER’S

MANUAL

New Contact Information

Keithley Instruments, Inc.

28775 Aurora Road

Cleveland, OH 44139

Technical Support: 1-888-KEITHLEY

Monday – Friday 8:00 a.m. to 5:00 p.m (EST)

Fax: (440) 248-6168

Visit our website at http://www.keithley.com

Part Number: 24809

Revision Level:

First Printing: March

A

1989

Copyright

WARNING

MetraByte Corporation assumes no liability for damages consequent

product. This product is not designed

in life support

All

rights reserved.

transmitted, in any form by any means, electronic. mechanical, photocopying, recording. or

otherwise, without the express

Information furnished by MetraByte Corporation

However,

infringements

granted by implication

No

no

responsibility

of

patents

part

of

this publication may

or

is

other rights of third parties which may result from

or

otherwise under any

with

prior

assumed

or

wriien permission

by

0

1989

to

its

the use

use;

its

components of a level of retiabi[ity suitable for use

critical applications.

be

reproduced. stored in a retrieval system. or

of

MetraByte Corporation.

is

believed

MetraByte Corporation

patent

tights

to

be accurate and reliable.

for

of

MetraByte Corporation.

of

nor for any

use.

No

this

license is

M3000/M4000 modules are not intrinsically safe devices and should not

environment unless enclosed in approved explosion-proof housings.

a

IBMB

PC/XT/AT

MetraBytem is

is

a

registered trademark

trademark

of

MetraByte Corporation.

of

International Business Machines Corporation.

be

used in an explosive

Safety Precautions

The following safety precautions should be observed before using this product and any associated instrumentation. Although some instruments and accessories would normally be used with non-hazardous voltages, there are situations where hazardous conditions may be present.

This product is intended for use by qualiﬁed personnel who recognize shock hazards and are familiar with the safety precautions required to avoid possible injury. Read and follow all installation, operation, and maintenance information carefully before using the product. Refer to the manual for complete product speciﬁcations.

If the product is used in a manner not speciﬁed, the protection provided by the product may be impaired.

The types of product users are:

Responsible body is the individual or group responsible for the use

and maintenance of equipment, for ensuring that the equipment is operated within its speciﬁcations and operating limits, and for ensuring that operators are adequately trained.

Operators use the product for its intended function. They must be

trained in electrical safety procedures and proper use of the instrument. They must be protected from electric shock and contact with hazardous live circuits.

Maintenance personnel perform routine procedures on the product

to keep it operating properly, for example, setting the line voltage or replacing consumable materials. Maintenance procedures are described in the manual. The procedures explicitly state if the operator may perform them. Otherwise, they should be performed only by service personnel.

Service personnel are trained to work on live circuits, and perform

safe installations and repairs of products. Only properly trained service personnel may perform installation and service procedures.

Keithley products are designed for use with electrical signals that are rated Installation Category I and Installation Category II, as described in the International Electrotechnical Commission (IEC) Standard IEC 60664. Most measurement, control, and data I/O signals are Installation Category I and must not be directly connected to mains voltage or to voltage sources with high transient over-voltages. Installation Category II connections require protection for high transient over-voltages often associated with local AC mains connections. Assume all measurement, control, and data I/O connections are for connection to Category I sources unless otherwise marked or described in the Manual.

Exercise extreme caution when a shock hazard is present. Lethal voltage may be present on cable connector jacks or test ﬁxtures. The American National Standards Institute (ANSI) states that a shock hazard exists when voltage levels greater than 30V RMS, 42.4V peak, or 60VDC are present. A good safety practice is to expect

that hazardous voltage is present in any unknown circuit before measuring.

Operators of this product must be protected from electric shock at all times. The responsible body must ensure that operators are prevented access and/or insulated from every connection point. In some cases, connections must be exposed to potential human contact. Product operators in these circumstances must be trained to protect themselves from the risk of electric shock. If the circuit is capable of operating at or above 1000 volts, no conductive part of

the circuit may be exposed.

Do not connect switching cards directly to unlimited power circuits. They are intended to be used with impedance limited sources. NEVER connect switching cards directly to AC mains. When connecting sources to switching cards, install protective devices to limit fault current and voltage to the card.

Before operating an instrument, make sure the line cord is connected to a properly grounded power receptacle. Inspect the connecting cables, test leads, and jumpers for possible wear, cracks, or breaks before each use.

When installing equipment where access to the main power cord is restricted, such as rack mounting, a separate main input power disconnect device must be provided, in close proximity to the equipment and within easy reach of the operator.

For maximum safety, do not touch the product, test cables, or any other instruments while power is applied to the circuit under test. ALWAYS remove power from the entire test system and discharge any capacitors before: connecting or disconnecting cables or jumpers, installing or removing switching cards, or making internal changes, such as installing or removing jumpers.

Do not touch any object that could provide a current path to the common side of the circuit under test or power line (earth) ground. Always make measurements with dry hands while standing on a dry, insulated surface capable of withstanding the voltage being measured.

The instrument and accessories must be used in accordance with its speciﬁcations and operating instructions or the safety of the equipment may be impaired.

Do not exceed the maximum signal levels of the instruments and accessories, as deﬁned in the speciﬁcations and operating information, and as shown on the instrument or test ﬁxture panels, or switching card.

When fuses are used in a product, replace with same type and rating for continued protection against ﬁre hazard.

Chassis connections must only be used as shield connections for measuring circuits, NOT as safety earth ground connections.

If you are using a test ﬁxture, keep the lid closed while power is applied to the device under test. Safe operation requires the use of a lid interlock.

5/02

If or is present, connect it to safety earth ground using the wire recommended in the user documentation.

!

The symbol on an instrument indicates that the user should refer to the operating instructions located in the manual.

The symbol on an instrument shows that it can source or measure 1000 volts or more, including the combined effect of normal and common mode voltages. Use standard safety precautions to avoid personal contact with these voltages.

The WARNING heading in a manual explains dangers that might result in personal injury or death. Always read the associated information very carefully before performing the indicated procedure.

The CAUTION heading in a manual explains hazards that could damage the instrument. Such damage may invalidate the warranty.

Instrumentation and accessories shall not be connected to humans. Before performing any maintenance, disconnect the line cord and

all test cables.

To maintain protection from electric shock and ﬁre, replacement components in mains circuits, including the power transformer, test leads, and input jacks, must be purchased from Keithley Instruments. Standard fuses, with applicable national safety approvals, may be used if the rating and type are the same. Other components that are not safety related may be purchased from other suppliers as long as they are equivalent to the original component. (Note that selected parts should be purchased only through Keithley Instruments to maintain accuracy and functionality of the product.) If you are unsure about the applicability of a replacement component, call a Keithley Instruments ofﬁce for information.

To clean an instrument, use a damp cloth or mild, water based cleaner. Clean the exterior of the instrument only. Do not apply cleaner directly to the instrument or allow liquids to enter or spill on the instrument. Products that consist of a circuit board with no case or chassis (e.g., data acquisition board for installation into a computer) should never require cleaning if handled according to instructions. If the board becomes contaminated and operation is affected, the board should be returned to the factory for proper cleaning/servicing.

TABLE

OF

CONTENTS Warranty CHAPTER

CHAPTER

1

2

CHAPTER 3

CHAPTER

CHAPTER CHAPTER

Appendix Appendix

4

5

6

7

8 9

10

A

B

4

Getting Started

Terminal Designations 1-1

Default

Quick

Mode

Hook-Up

1-2

1-3

Functional Description

Block

Diagram 2-3

Communications

RS-232C 3-2

Multi-party Connection 3-3 Software Considerations 3-4

Changing Baud Rate

RS-485

3-6

3-5

RS-485 Multidrop System 3-7

Command

Table

User

Commands

Error Messages

Set

of

Commands

4-6

4-7

4-20

Setup Information and Command

Command Syntax 5-2 Setup Hints

Digital

110

Manual ModedDigital Controller Input Limit Switches

Power

Supply

5-9

Function

6-4

6-5

Inputs

6-1

Troubleshooting Cali brat

M4000

Slope Control

Input Data Scaling

Watchdog Timer Analog Readback

(ASCII TABLE M3000/4000

ion

Features

10-1

)

Data

10-4

10-6

10-7

Sheet

3

WARRANTY

MetraByte warrants each in materials and workmanship under normal conditions of use and service and will replace any component

tation charges prepaid within one year

no liability, expressed or implied, beyond its obligation to replace any component involved. Such warranty is in lieu of

WARNING

The

circuits and software contained in

proprietary. Purchase of these products does not transfer any rights any license to

the

circuits or software used or decompiling of the software program of the software program by any means

As

explained in the setup section, all setups are performed entirely from the

outside of the

M3000/4000

M3000

found

and M4000 series module to be free from defects

to be defective, on its return

of

its original purchase. MetraByte assumes

all

other warranties expressed or implied.

M3000

and

to

M4000

MetraByte, transpor-

series modules are

or

in

these products. Disassembling

is

explicitly prohibited. Reproduction

is

illegal.

module. There

is

no need to open the module

grant

because there are no user-serviceable parts inside. Removing the cover or

tampering with, modifying, or repairing by unauthorized personnel

matically void the warranty. MetraByte

tial

damages.

is

not responsible for any consequen-

will

auto-

RETURNS

When returning products Authorization Number and shipping instructions. Write the Return Authorization

Numberon the outside ofthe shipping box. MetraBytestrongly recommendsthat you insure the product they will not

be

for

accepted.

for

any

reason, contact the factory and request a Return

value prior to shipping. ttems should not

be

returned collect as

4

Chapter

1

Getting

Introduction

The MetraByte

analog output interfaces. They are designed to

computer and communicate with standard ASCII commands are used to control which is scaled to provide commonly used current and voltage ranges. An on-board

microprocessor is used

gent analog output functions.

M3000

sensitive applications where some

M3000

read back.

M4000

enhancements

versions provide a basic computer-to-analog output interface for costunits feature step-function outputs, fixed input scaling, and no analog

versions perform alI

M3000/4000

to

:

is a series of completely self-contained computer-to-

be

mounted remotely from a host

RS-232

a

1

2-bit

provide the communications interface and many intelli-

of

the intelligent enhancements are not required.

of

the

M3000

functions plus many additional intelligent

and

DAC

RS-485

(Digital-to-Analog Converter)

serial ports. Simple

Started

Controlled output slew rates True analog readback

Programmable input data scaling Programmable starting value

Watchdog timer This manual has been written

Basic operating characteristics noted, the information in this manual applies to both versions. Commands and

functions exclusive

Terminal Designations

All

M3000

slight variations between currentholtage and

1

2

Pins 1 and 2 are the connections input data is scaled

Voltage outputs can source or sink current.

and

+I

-I

to

M4000

OUT or

OUT

or

so

the

units have similar terminal designations, although there are

+V

-V OUT

that the voltage at

to

of

M4000

OUT

to

be a guide for both the M3000 and

both models are identical and unless otherwise

are

so

noted in the text.

RS-232/RS-485

the analog output signal. On voltage models, the

+V

OUT

is

positive with respect to -V OUT.

models.

M4000

units.

1-2

M3000/4000 USERS

MANUAL

On current output models, the output current flows from the

-I

OUT

terminal, positive voltage level than the current.

Pins 1 and 2 are electrically isolated from the other pins. Pin

3

Pin 4 Pin

5

Pins 3-5 are digital input pins. They may be used as general-purpose inputs may be set-up to provide special functions that control the analog output. The

standard factory set-up configures the down control

negative true. A full functional description Pin 6

Grounding this pin places the module in Default Mode, described in detail below. Pin

7

8

Pins 7 and 8 are connections to the serial communications lines connecting the module to the host computer or terminal.

so

for a typical resistive load, the

-1

OUT

terminal. Current outputs can only source

D12 DI 1 /UP*

DIO/DN*

UP*

and

of

the analog output. The * designation indicates that the labels are

of

DEFAULT*

TRANSMIT

RECEIVE

or

DATA*

DATA

+I

OUT

DN*

pins to provide manual up and

these pins may be found in Chapter

+I

OUT terminal

terminal will be at a more

to

or

the

they

6.

On RS-232 models, the TRANSMIT pin

module. The RECEIVE pin

On RS-485 versions, communications lines.

respectively.

9

1OGND

Pins 9 and

30V unregulated power.

Default

All

M3000/4000

Read Only Memory)

EEPROM

rate, address, parity, etc.

tion is retained even

necessary to open the module case.

The

EEPROM

parameters may be configured remotely through the communications port without having

drawback in using EEPROM instead

to

V+

10

are the powerconnections. The M3000/4000 modules operate on

Mode

modulescontain an EEPROM (Electrically Erasable Programmable

replaces the usual array

provides tremendous system flexibility since

physically change switch and pot settings. However, there

DATA

is

the serial input into the module.

and

DATA*

DATA

to

and

DATA*

store setup information and calibration constants. The

of

The

memory is nonvolatile which means that the informa-

if

power is removed.

is

the serial output connection from the

are connections to the balanced

are sometimes labeled

switches and pots necessary to specify baud

No

batteries are used

of

switches; there is no visual indication of the

DATA+

so

all

of the module’s setup

RS-485

and

DATA-

it

is never

is

one minor

10-

Getting Started

setup information in the module. It is impossible to tell just by looking at the module

what the baud rate, address, parity and other settings are.

communications with a module whose address and baud rate are unknown.

overcome this, each module has an input pin labeled DEFAULT*. By connecting this

pin to Ground, the module is put in a known communications setup called Default

Mode.

It

is difficult to establish

1-3

To

The Default Mode setup

Grounding the DEFAULT* pin

The setup may

of

the setups stored in the module. In Default Mode, all commands are available.

A

module in Default Mode will respond

included in every command for proper responses. The

address may be read back with the

address character is to deliberately generate an error message. The error message

outputs the module’s address directly after

Setup information

Baud rate and parity setups may be changed without affecting the Default values of

300

baud and no panty. When the DEFAULT* pin is released, the module automati-

cally performs a program reset and configures itself to the baud rate and parity stored

in the setup information.

The Default Mode

orcomputer forthe purpose

a

module

RS-232

Software

that you begin to get familiar with the module by setting

using a dumb terminal or a computer that acts like a dumb terminal. Make the

connectionsshown inthequick hook-updrawings, Figures

in the Default Mode

communications package on yourcornputerto put

this step varies from computer

inst ructions.

in

&

is

be

read back with the Read Setup

in

is

Default Mode may not be used in a string with other modules.

RS-485

not required

Quick

is:

300

baud, no parity, any address is recognized.

does

not change any of the setupsstored in EEPROM.

(RS)

a

module may

intended to

of

identifying and modifying setupvalues. In most cases,

command

to

any address. A dummy address must be

ASCII

RS

command. An easy way to determine the

the

“?”

prompt.

be

changed at will with the Setup

be

used with asingle module connected toaterminal

to

determine

value of the module

(SU)

command.

Hook-Up

to

begin using your

by

grounding the DEFAULT* terminal. Initialize the terminal

to

computer, refer to your computer manual

M3000/4000

it

into the “terminal” mode. Since

module. We recommend

up on the bench. Start by

1.1

or

1.2.

Putthe module

all

far

Connect a suitable voltmeter or ammeter to the output connections

monitor the output signal.

current-output modules, a sense resistor and a voltmeter may be used as shown in

Fig.

1.1.

Turn power on

connector. The output signal should increase in value as the UP* pin

release the UP* pin and ground the DN* (down) pin. The output signal should

decrease in value as the pin

If

an ammeter

to

the module. Momentarily ground the UP* pin on the

is

held

is

not available

low.

to

measure the signals from

of

the module to

is

held

low.

Now

1-4

M3000/4000

USERS

MANUAL

This demonstrates the “Manual Mode” method

quick check to see if the module

Use your terminal to type the command

is

connected and working properly.

$1

RD

of

controlling the output. It is also

and

terminate the command with a

a

carriage return. The module will respond with an * followed by the output data

reading. The data includes sign, seven digits and a decimal point. For example, a

typical reading might be

*+00015.00.

This is an output status reading and it should

closely correspond with the reading on your meter.

Now

type the command:

$1

A0+00010.00

The module should respond with

rnilliamps). This demonstrates the Analog Output

primary method

If

you have a voltage output module,try these commands:

$1

A0+00000.00

$1

AO+OOlOO.OO

$1

A0+01000.00

$1

A0+01234.00

and terminate with a carriage return.

I*’

and the output will change to

of

controlling the analog output.

(terminate with a carriage return)

(AO)

command, which

10

millivolts

is

(or

the

Far current output models these commands are more appropriate:

$1

A0+00004.00

$1

A0+00020.00

$1

A0+00010.00

Remember to terminate each command with a carriage return. Once you have a response from

the

module

you

can turn

to

the Chapter 4 and get

familiar with the command set.

All

modulesareshippedfromthefactory

of

1,

300

baud

delay. Refer

rate,

no

to

the Chapter

linefeeds, no parity, limits off, no echo and two-character

5

to

configure

with asetupthat includesachanneladdress

the

module to your application.

Getting

Started

1-5

-f--l

Current

Output

Ammeter

Figure

voltmeter

1.1

RS-232C

YQkqe

Output

Quick

M

3QQQ

Analog

Output

RS232C

Hook-Up.

Cumnt Output Output

Ammeter

Voltwe

voltmeter

FIGURE

1.2

RS-485

Quick

Hook-UP.

1-6

M3000/4000

USERS MANUAL

RS-485

An

Quick

RS-485

Hook-up

to a RS-232

port

module may be easily interfaced to an RS-232C terminal for evaluation

purposes. This connection is only suitable for benchtop operation and should never be used for a permanent installation. Figure will work provided the RS-232C transmit output and the

and

RS-232C

1489

receive threshold is greater than

style interface

IC’s

will satisfy this requirement. With this connection, characters generated by the terminal characters, the IocaI echo

If

the current limiting capability

1

kQ

resistor in series with the RS-232C output.

Cumnt

Output

on

the terminal should be turned

of

the RS-232C output is uncertain, insert a

Ydtqe

Output

1.3

shows the hook-up.

is

current limited to less than 50mA

OV.

will

be echoed back.

This

connection

All terminals that use

To

avoid double

off.

100

1488

to

-i-b

Ammeter

Vottmeter

FIGURE

1.3

RS-485

Quick

Hook-Up

using

an

RS-232

Port.

Chapter

2

Functional Description

The MetraByte

analog process control signals in response to simple digital commands from a host

computer. The M3000/4000 units are completely self-contained and are designed to

be

operated remotely from the host. Digital commands are transmitted to the M3000/

4000

units using standard RS-232 or RS-485 communications links. Commands and

responses are in the form

The

ASCII

modems as well as intelligent controllers and computers. Figure2.1 shows afunctional blockdiagrarn ofthe M3000/4000. The key block is the

12-bit Digital to Analog Converter (DAC). The DAC converts digital data derived from host commands info the desired analog output. All of the other components provide

a

supporting role for proper operation

An 8-bit the host and the DAC. The microprocessor receives commands and data from the

host computer through a serial communications components are used to interface the microprocessor to either communications standards. Commands received by the microprocessor are thoroughly checked for syntax and data errors. Valid commands are then processed to

complete the desired function. A wide variety the DAC, read status information, and to configure the module to fit the user’s

requirements. Responses to the host commands are then produced by the micropro-

cessor and transmitted back to the host over the RS-232/RS-485 serial link.

CMOS

13000/4000 Computerto Analog Output interfaces provide accurate

of

simple English ASCII character strings for ease of use.

protocol allows the units to be interfaced with dumb terminals and

of

the DAC.

microprocessor is

used

to provide an intelligent interface between

port.

Specialized communications

RS-232

of

commands are available to control

or

RS-485

An Electrically Erasable Programmable Read-only Memory (EEPROM)

retain important data even setup information such as the address, baud rate, and parity as well data.

In response to host commands, the microprocessor produces the appropriate digital

data necessary to control the DAC. Digital data is transmitted

opto-isolators

current that

output current is then processed and amplified by signal conditioning circuits to produce the desired output voltage orcurrent. Output protection circuits are included

which provide electrical isolation. The DAC produces a precise analog

is

directly proportional to the magnitude of the digital data. The DAC

if

the module is powered down. The EEPROM contains

to

the

is

used to

as

calibration

DAC

through

2-2

M3000/4000

to protect the module from potentially damaging output faults.

USERS MANUAL

M4000

to monitor the output signal. The converts the signal level to digital data. The digital data is optically isolated and may be read by the microprocessor. This circuitry allows the M4000 user to directly monitor the output signal and ensure its integrity.

The

the raw 1Oto30voltssupplied

It produces

232 units, the power supply produces

tions standard.

circuitry. The power supplied

input power and communications connections. The transformer along with the optoisoIators provide

circuitry. The isolation barrier is extremely helpful in breaking ground loops and isolating troublesome common-mode voltages that are often found in large systems.

The isolation barrier also provides damage protection for the module and the host in cases where the output lines may accidently contact

The combination sor produces a very powerful system for the generation of process control signals. The power

multidrop capability, data formatting in engineering units, limit checking, digital calibration, and a host of other features not possible with unintelligent analog output systems.

models also feature asimple Analog to Digital Converter (ADC) which is used

ADC

input is tied directly to the analog output and

last

major block in the diagram is the power supply. The power supply converts

bytheuserintoregulatedvoltagesusedinthe

+5V

necessary

It

also produces

to

an

isolation barrier between the output section and the rest

of

an accurate high-resolution DAC and a dedicated rnicroproces-

of

the microprocessor is used

to

operate the microprocessor and

+I5

volts to power the

the DAC and output circuitry

+1

EEPROM.

OV

necessary for the RS-232 communica-

DAC

and associated output

is

transformer isolated from the

AC

power lines.

to

provide software addressing

module.

On

RS-

of

the

for

During normal operation, the microprocessor constantly updates the

rate

of

1000 times per second, even

this characteristic to provide controlled output

are created by incrementally stepping the precisely calculated by the microprocessor. The small output steps created at

millisecond intervals are used to approximate ramp outputs. Slope rates are programmable and may be changed at any time with simple commands. Linear ramps may be initialized with a single command from the host computer. intervention or monitoring

is

required from the host; the M4000 does the rest.

if

the output

is

stable.

slew

rates. Linear output ramp signals

DAC

every millisecond with values

The

DAC

M4000

data at

fully utilizes

No

further

a

Functional

Description

2-3

Chapter

3

Communications

Introduction

The

M3000/4000

all popular computers and terminals. are performed with printable processed with string functions common

BASIC.

ware drivers are necessary for operation. The modules can be connected to autoanswer modems for long-distance operation without the need for a supervisory computer. The

For computers that support

modules have been carefully designed to be easy

All

ASCII

communications

ASCII

format makes system debugging easy with a dumb terminal.

characters. This allows the information

to

most high-level languages such as

RS-232C,

no special machine language

to

and from the modules

to

interface

to

be

soft-

to

The MetraByte system

tions port with a single 4-wire cable. Up togetheron

ten, although a string host on a polling system; that

and must be interrogated by the host. A module can never initiate acommunications sequence. A simple command/response protocol must be

communications collisions and Communications

character

A

complete description of all commands is given in the Chapter

command/response sequence would

one

ASCII

cable;

to

command codes such

Command:

Response:

A

command/response sequence

The host may not initiate a new command until the command

collisions. A valid response can be in one of three forms:

is

complete. Failure to observe this rule will result in communications

1

)

a normal response indicated by a

2)

an error message indicated by a

3)

a

communications time-out error

allows

124

of

124

multiple modules

with repeaters. A practical limit for

units is possible. The modules communicate with the

is,

the

M3000/4000

$1

RD

*+00123.00

to

be connected to a communica-

to

32

RS-485

each module responds

data

errors.

modules

as

RD

look

like this:

is

not complete until a valid response is received.

' ? '

to

' * '

prompt

are

Read

prompt

modules may be strung

RS-232C

to

its own unique address

strictly

performed with two

Data

from the analog output.

response

units is about

observed to avoid

4. A

from a previous

or

three-

typical

When a module receives a valid command,

the desired function, and then communicate the response back to the host Each

it

must interpret the command, perform

3-2

M3000/4000

command has an associated delay time in which the module is busy calculating the

response. specified in Table

communications time-out it

error usually results when an improper command prompt or address is transmitted.

The table below lists the timeout specification for each command:

Mnemonic Timeout

DI,

HX,

ID

All other commands

If

the host does not receive a response in an appropriate amount

WE

USERS

3.1, a communications time-out error

MANUAL

is

assumed that no response data is forthcoming. This

3mS

130mS

35

mS

has

occurred. After the

of

time

Table The timeout specification

when the module starts to transmit a response.

Data

All MetraByte modules communicate in standard

This format provides one start bit, seven data bits, one panty bit and each character.

3.1

Response Timeout Specifications.

is

the turn-around time from the receipt

Format

of

a command to

NRZ

asynchronous data format.

one

stop bit for

RS-232C

between computing equipment.

to virtually all popular computers without any additional hardware. Although the

232C

MetraByte system allows for several modules to be connected network structure.The advantages offered by the

1)

2)

3)

4) compatible with dumb terminals

is the most widely used communications standard for information transfer

RS-232C

standard

widely used by all computing equipment

no additional interface hardware in most cases

separate transmit and receive lines ease debugging

is

designed to connect a single piece

versions

of

the

M3000/4000

of

equipment to a computer, the

RS-232C

standard are:

will interface

in

a

daisy-chain

RS-

However,

1)

2)

3)

4)

5)

6)

7)

Single

Figure Default Mode to enter the desired address, baud rate, and other setups (see Setups).

RS-232G

low

noise immunity

short usable distance

maximum baud rate

greater communications delay less re lia ble-daisy-c hai n connection

wiring host software must handle echo characters

is

Module

1.1

shows the connections necessaryto attach one moduleto a host. Use the

suffers from several disadvantages:

-

50

to

200

feet

-

19200

in

multiple-module systems

slightly more complex than

Connection

RS-485

Communications

3-3

The use line.

of

echo is not necessary when using a single module on the communications

Multi-party Connection

RS-232C

4000

single communications port. The wiring necessary to create the daisy-chain isshown in Figure the RECEIVE input of the next module in the daisy chain. This wiring sequence must be followed until the output of the last module in the chain is wired tathe Receive input

of

the host.

echo address to avoid communications collisions

characters transmitted by the host are received

passed

ofthe host. Inthis module. command, it will respond by transmitting the response on the daisy chain network. The response data will be ripple through any other modules in the chain until reaches its final destination, the Receive input

is

not designed to be used in a multiparty system; however the

modules can

3.1.

Notice that starting with the host, each TRANSMIT output is wired

All

all

received data (see Setups). Each module must be setup with its own unique

on to the next station until the information

If a module in the chain is correctly addressed and receives a valid

be

daisy-chained

modules in the chain must be setup

to

allow many modules

(see

by

is

mannerallthecommandsgiven

bythe host areexamined byevery

of

to

be connected to a

to

the same baud rate and must

Setups). In this network, any

each module in the chain and

echoed backto the Receive input

the host.

M3000/

to

it

3-4

M3000/4000

The daisy chain network must be carefully implemented to avoid the pitfalls inherent

in its structure. The daisy-chain

communications link will bring down the whole system. Several rules must be

observed to create a working chain:

1.

All

wiring connections must be secure; any break

power, ground or communications breaks the chain.

2.

All

modules must be plugged into their connectors.

3. All modules must be setup for the same baud rate.

4.

All

modules must

USERS

be

MANUAL

is

aseries-connected structure and any break in the

setup for echo.

in

the wiring,

Software

If

the

messages on its Receive input along with the responses from the module. This can

be

handled by software string functions

begins with

A

properly addressed

characters in the command including the terminating carriage return. Upon receiving the carriage return, the module will immediately calculate and transmit the response to the command. During this time, the module will not echo any characters that

appear on its receive input. However, if a character tation period, it will be stored in the module's internal receive buffer. This character

will be echoed after the response string is transmitted by the module. This situation

will occur

carriage return. In this case the linefeed character will be echoed after the response

string has been transmitted.

The daisy chain

in the chain receives a character the module's internal UART. This method

nications since the UART eliminates any slewing errors caused by the transmission

lines. However, this method creates adelay in propagating the character through the

chain. The delay is equal to the time necessary to retransmit one character using the

baud rate setup in the module:

Considerations

host

device is a computer,

a

' * '

or

' ? '

if

the host computer appends a linefeed character

also

affects the command timeout specifications. When a module

it

must be able to handle the echoed command

by

character and ends

M3000/4000

module in a daisy chain will echo all of the

it

is

echoed by retransmitting the characterthrough

observing that a module response always

with a carriage return.

is

received during this compu-

on

the command

is

used to provide more reliable comrnu-

Baud Rate Delay

300

600

1200

2400

4800

9600

19200

38400

33.30 m

16.70mS

8.33mS

4.17mS

2.08mS

1.04rnS

520pS

260pS

S

Communications

3-5

One delay time is accumulated for each module in the chain. For example, modules are used in a chain operating at 1200 baud, the accumulated delay time is

4

X

8.33

rnS

=

33.3

mS This time must

calculate the correct communications time-out error.

For modules with RS-232C outputs, the programmed communications delay speci-

fied in the setup data (see Chapter

(00)

followed by an idle line condition for one character time. This results in a delay

of two character periods. For longer delay times specified in the setup data, this sequence

an RS-232C daisy chain since each module in the chain adds one character communications delay.

Changing Baud

It

is possible to change the baud rate

must

1. Use the Setup

in the chain. Be careful not to generate a reset during this process. A reset can be

caused by the Remote Reset

2.

the Read Setup same baud rate.

is

repeated. Programmed communications delay

Rate

be

done carefully to avoid breaking the communications link.

(SU)

command

(RR)

Verify that all the modules in the chain contain the new baud rate setup using

(RS)

command. Every module in the chain must be setup for the

be

added to the times listed in Table 3.1 to

5)

is implemented by sending a

is

of

an RS-232Cdaisychain on-line. This process

to

change the baud rate setup

command or power interruptions.

NULL

seldom

on

necessary in

each module

if

four

character

of

3.

Remove power from all the modules for at least 10 seconds. Restore power

to the modules. This generates a power-up reset in each module and loads in the new

baud rate.

4.

Change the host baud rate

5.

Be sure to compensate for a different communications delay as a result

new baud rate.

Using A Daisy-Chain With A Dumb

A

dumb terminal can be used to communicate

terminal is connected

commands typed into the dumb terminal double characters when typing commands,

turn

off

the local echo. The daisy chain will provide the input command echo.

in

the same manner

to

the new value and check communications.

Terminal

to

a

daisy-chained system. The

as

a

computer used as a host. Any

will

be echoed by the daisy chain.

set

the terminal

to

full duplex mode or

To

of

the

avoid

RS-485

rnultidropped systems that can communicate at high data rates over long distances. RS-485 is similar switching from 0 to mode voltages from

transmission over great distances.

is a recently developed communications standard

to

RS-422 in that it uses a balanced differential pair of wires

5Vto

communicate

-7V

to +12V without

data.

RS-485

RS-485 receivers can handle common

loss

of

data, making them ideal for

differs from RS-422 by using one

to

satisfy the need for

3-6

M3000/4000

balanced pair of wires for both transmitting and receiving. Since an RS-485 system

cannot transmit and receive at the same time it is inherently a half-duplex system.

RS-485 offers many advantages over RS-232C:

1)

balanced line gives excellent noise immunity

2)

can communicate with MetraByte modules at 38400 baud

3)

communications distances up to

4)

true multidrop; modules are connected in parallel

5)

can disconnect modules without losing communications

6)

up

to

32 modules on one line;

7)

no communications delay due to multiple modules

8)

simplified wiring using standard telephone cable

USERS

MANUAL

10,000

124

with repeaters

feet.

RS-485 does have disadvantages.

support for this new standard. Interface boards are available for the IBM

compatibles and other

gains popularity. An MetraByte offers interface converters

These converters also include power supplies to power up To

expand an RS-485 system even further, repeater

MetraByte to string up to 124 modules on one communications

RS-485

Figure

that every module has a direct connection to the host system.

modules may be unplugged without affecting the remaining modules. Each module must be setup with a unique address and the addresses can be in any order. All RS-

485

that the connector pins on each module are labelled with notations (B), (R),

(Y).

Multidrop

3.2

illustrates the wiring required for multiple-module

modules must be setup for no This designates the colors used on standard 4-wire telephone cable:

Label Color

(6)

GND

(R)

v+

(G)

DATA* Green

(Y)

DATA Yellow

RS-485

System

system usually requires an interface.

Black Red

Very

few computers or terminals have built-in

PC

and

equipment will become available as the standard

to

convert RS-232C and RS-422 to

to

32

MetraByte modules.

boxes

are available from

RS-485.

port.

echo

to

avoid

RS-485

bus conflicts (see Setup).

system. Notice

Any

number

Also

note

(G),

and

of

This

color convention

cable is used, it guarantee correct installation.

DATA* on the label is the complement

is

used to simplify installation.

only necessary

to

If

standard 4-wire telephone

match the labeled pins with the wire color to

of

DATA (negative true).

Co

rnmunications

3-7

I

3-8

M3000/4000

USERS

MANUAL

To minimize unwanted reflections on the transmission line, the arranged as a line going from one module to the next. ‘Tree’

of the transmission line should be avoided. When using long transmission lines and/

or high baud rates, the data lines should be terminated at each end with resistors. Standard values of

During normal operation, there are periods of time where all and the communications lines are in an ‘idle’ high impedance condition. During this condition, the lines are susceptible to noise pickup which may be interpreted as random characters on the communications line. To prevent noise pickup, all systems should incorporate resistors will maintain the data lines in a ‘mark‘ condition when all drivers are

MetraByte Special care must be taken with very long busses (greaterthan

error-free operation. Long busses must be terminated as described above. The use of twisted cable for the

Use

parity and checksums along with the

transmission errors. In situations where many modules are used on a long line,

voltage drops in the power leads becomes an important consideration. The wire is used both as a power connection and the common reference for the

transmission line receivers

as

acommon-mode voltage

of

-7V.

should be kept below

A1

000

series converter boxes have the

DATA

of common-mode voltage. For reliable operation, the common mode voltage

-5V.

180R

1K

in

the modules. Voltage drops in the

to

or

220Q

ohm bias resistors as shown in Figure

and

DATA*

the receivers. The receivers are rated for a maximum

are acceptable.

1

Ki2

lines will greatly enhance signal fidelity.

‘#

form

of

or

RS-485

resistors built-in.

all commands

bus

should be

random structures

200

ohm

drivers are

RS-485

3.2.

The

off.

1000

feet) to ensure

to

detect

GND

leads appear

off

To avoid problems with voltage drops, modules may be powered locally rather than transmitting the power from the host. Inexpensive ’calculator’ type power supplies are useful in remote locations. When local supplies are used, be sure to provide a ground reference with a third wire to the host or through a good earth ground. With local supplies and an earth ground, only two wires for the data connections are

necessary.

Communications

All

MetraByte modules with

units of communications delay after a command has been received (see Chapter This delay is necessary when using host computers that transmit a carriage return

as a carriage return-linefeed string. Without the delay, the linefeed character may collide with the first transmitted character from the module, resulting

If

the host computertransmits acarriage return as a single character, the delay may

be set

to

zero to improve communications response time.

Delay

RS-485

outputs are setup at the factory to provide two

5).

in

garbled data.

Chapter

4

Command

The M3000/4000 modules operate with a simple command/response protocol to control host computer or terminal before the module will respond with useful data. A module can never initiate a communications sequence. A variety exploit the full functionality sample format

Command

Each command message from the host must begin with a command prompt character to signal to the modules that a command message is to follow. There are

two valid prompt characters; a dollar sign character

response message from the module. A short response data necessary to complete the command. The second prompt character is the pound sign character

The prompt character must be followed by asingle address character identifying the

module to which the command is directed. Each module attached to a common communications port must be setup with its own unique address

may be directed

the Setup (SU) command. Printable ASCII characters such as

(ASCII

all

module functions. A command must be transmitted to the module

of

commands exists

of

the

modules. A list

for

each command is listed in Table

of

available commands and a

4.1.

Structure

($)

is

used to generate a short

is

the minimum amount of

(#)

which generates long responses (will

to

the proper unit. Module addresses are assigned by the user with

$41) are the best choices for address characters.

be

covered later).

so

that commands

‘1

’

(ASCII $31) or

Set

by

the

to

‘A’

The address character is followed by a two or three-character command that

identifies the function to be performed by the module. are listed in Table

transmitted as upper-case characters. Atwo-characterchecksum may be appendedto any command message (except the

ID

command) as a user option. See ‘Checksum’ later in this chapter

All

commands must be terminated by a Carriage Return character

all

command examples in this text the Carriage Return

by the symbol

Data

Structure

Many commands require additional data values to complete the command definition

as shown in the example commands in Table these commands is described in

4.1

‘CR’.)

along with

a

short

full

function definition. Commands must

4.1.

in the complete command descriptions.

All

of the available commands

be

(ASCII

is

either implied or denoted

The particular data necessary for

$OD).

(In

4-2

M3000/4000

USERS

MANUAL

The most common type of data used in commands and responses is analog data.

Analog data is always represented in the same format for all models in the

4000

sign, five digits, decimal point, and

series. Analog data is represented as a nine-character string consisting of a

two

additional digits. The string represents a

M3000/

decimal value in engineering units. Examples:

+I

2345.68

+00100.00

-00072.10

-00000.00

When using commands that require analog data character string must be used, even

this results Analog

in

a SYNTAX

data

responses from the module will always be transmitted in the nine-

ERROR.

if

some digits are not significant. Failure to do

as

an argument, the

full

nine-

character format. This greatly simplifies software parsing routines since all analog data is in the same format for all module types.

In

many cases, some of the digits in the analog data may not be significant. For

instance, in the M3151 0 to 20mA output module, the data is scaled in mitliamps. The full scale output is +00020.00mA. The

left

three digits have no significance. However,

the data format is always adhered to in order to maintain compatibility with other

module types. The maximum computational resolution

the resolution that may be represented by an analog datavariable. This may

round-off errors in some cases. For example, a limit value may

4000

module using the

Command:

Response:

‘HI’

command:

$1

Hl+l2345.67

t

of

the module is 16 bits, which is

be

stored in a

less

than

lead

M3000/

to

The limit value is read back with the Read Hlgh (RHI) command:

Command:

Response:

$1

RHI

*+12345.60

It appears that the data read backdoes not match the value that was originally saved. The error is caused by the fact that the value saved

resolution values saved in the module’s

of

the module. This type of round-off error only appears when large data

EEPROM

are read back. In most practical applications,

exceeds

the computational

the problem is non-existent. The Digital Input, Hex Output and Setup commands use hexadecimal representa-

tions

of

data. The data structures for these commands are detailed in the command

descriptions.

Write Protection

Many

of

the commands listed in Table 4.1 are underthe heading of ‘Write Protected

Commands’. These commands are used to alter setup data in the module’s

Command Set

4-3

EEPROM.

All write-protected commands must be preceded by a Write Enable before the protected command may be executed.

MisceIlaneous

The address character must be transmitted immediately after the command prompt character. After the address character the module will ignore any character below ASCII

the command message for better readability if desired.

The length of acommand message is limited to addressed module receives a command message

module will abort the whole command sequence and no response will result.

If

a properly addressed module receives a second command prompt before it

receives a

Response

Response messages from the module begin with either an asterisk

or

a

question mark ment of a valid command. The messages are terminated with a

to acknowledge that the command has been executed commands send data information following the

all

commands may be found in the detailed command description.

They are write protected to guard against accidental

Protocol

$23

(except, of course,

Notes

CR).

This allows the use

20

printable characters.

of

CR,

the command

Structure

' ? '

(ASCII

will

be aborted and no response will result.

$3F)

prompt. The

'

?

'

prompt precedes an error message.

CR.

Many commands simpIy return

' * '

prompt indicates acknowledg-

' '

prompt. The response format

loss

of

spaces (ASCII

more than

20

by

the module. Other

of setup data.

(WE)

command

$20)

within

If

a properly

characters the

' '

(ASCII

All

a

' * '

$2A)

response

character

of

The maximum response message length

A command/response sequence is not complete until a valid response is received. The host may not initiate a new command until the response from a previous command is complete. Failure to observe this rule will result in communications collisions. A valid response can be in one of three forms:

I)

a normal response indicated by a

2)

an error message indicated by

3)

a communications time-out error

When a module receives avalid command, the desired function, and the communicate the response back to the host. Each

command has an associated delay time in which the module is busy calculating the response.

specified in Table

communications time-out

error usually results when an improper command prompt or address

Long

When the pound sign

form' response. This type

If

Form

the host

does

a communications time-out error has occurred. After the

3.1

Responses

'#I

not receive a response in an appropriate amount of time

it

is assumed that no response

command prompt

of

response will echo the command message, supply the

is

20 characters.

*

'

prompt

a

?

prompt

it

must interpret the command, perform

data

is

forthcoming. This

is

transmitted.

is

used, the module respondswith a'long

4-4

M3000/4000

USERS

MANUAL

necessary response data and will add a two-character checksum to the end message. Long form responses are used when the host wishes

command received by the module. The checksum is included to verify the integrity

of

the response data. The

For example:

Command:

Response: *+00072.10

Command:

Response: *1 RD+00072.1 OA4 (A4=c hec ksu m)

Checksum

It

verifies that the message received is exactly the same as the message sent. The

checksum ensures the integrity

Command Checksum A

two-character checksum may

module as a user option. When a module interprets a command, extra characters and assumes that it is a checksum. the module will perform the command normally. present, the module calculates the checksum for the message. checksum does not agree with the transmitted checksum, the module responds with a

‘BAD

agree, the command is executed.

responds with

is

atwo character hexadecimal value appended to the

CHECKSUM’

‘SYNTAX

‘ # ‘

command prompt may be used with any command.

$1

RD

#I

RD

of

the information communicated.

be

appended to any command (except ‘ID’) to the

error message and the command is aborted.

If

the module receives a single extra character, it

ERROR’

and the command is aborted.

(short

(long

If

the checksum is not present,

If

the two extra characters are

form)

to

end

of

a message.

it

looks

If

the calculated

If

the checksums

For

example:

of

the

verify the

for

the two

Command: Response: *+00072.10

Command: Response: ?1

Response Checksums

If

the long form ’#‘version of acommand istransmitted to a module, achecksum will

be appended

Command:

Response: *+00072.10

Command:

Response: *1 RD+00072.1OA4

to

the end

$1

RD

$1

RDEB

$1

RDAB (incorrect checksum)

BAD

CHECKSUM

$1

RDE

SYNTAX

of

the response. For example:

$1

RD

#1

RD

ERROR

(no checksum)

(with checksum)

(one extra character)

(short form)

(long

(A4zchecksu

form)

m)

Command Set

4-5

Checksum

The checksum is calculated by summing the hexadecimal values characters in the message. The lowest order two hex digits

the checksum. These equivalents and appended to the message. This ensures that the checksum is in the form

of

Example: Append a checksum

Characters: ASCII hexvalues: 23 Sum (hexaddition) 23+

Thechecksum isE7 (hex).Appendthecharacters Eand7totheend ofthe message:

#I

HX07FFE7.

Example: Verify the checksum of a module response

Calculation

of

all

the

ASCII

of

the sum are used as

two

digits are then converted to their

printable characters.

to

the command

#

The checksum is the two characters preceding the Add the remaining character values:

*lRDi00072.10

2A+31+52+44+26+30+30+30+37+32+2E+31

1

31

+

H

48

48+

#I

X

58

58i

HX07FF

0

30 37

30+

7

37+

*1

RD+00072.1 OA4

CR:

ASCII

F

46 46+

A4

+30=2A4

character

F

46

1E7

46=

The two lowest-order hex digits c h ec ksu m

The transmitted checksum is the character string equivalent to the calculated hex integer. The variables must be converted to like types in the host software to determine equivalency.

If

checksums do not agree, a communications error has occurred.

If

a

module is setup

the c hecksu m calcu tat io n

Parity bits are never included in the checksurn calculation.

M3000/4000

Table 4.1 shows all the M3000/4000 commands. For each case, atypical command

and response acknowjedgment. For clarity, Table

commands that are common to both the write protected commands from commands that are not write protected.

Each

commands are listed in alphabetical order according to command nomenclature.

Commands that are exclusive to the M4000 are noted near the right hand margin. For example:

.

User

is

shown. Note that some commands only respond with an * as an

M3000/4000

to

provide Iinefeeds, the linefeed characters are

Commands

usercommand isdescribed indetail following Table 4.1.

of

the sum are

A4

which agrees with the transmitted

not

inctuded in

.

4.1

separates

M3000

and

M4000

M4000.

commands from the

Table

4.1

also separates

AIIof

the

Manual

Slope

(MS)

(M4000)

4-6

M3000/4000

USERS

MANUAL

Table

Command Definition

M3000/4000

ACK Acknowledge

A0

DI Digital Input HX Hex Output RAO Read Analog Output RD Read Data RHI Read High Limit

RID

RLO Read Low Limit RMS Read Manual RMX Read Maximum RMN Read Minimum RS Read Setup

RSU

WE Write Enable

The following HI High Limit

ID Identification

LO

RR

su

TM

X

N

4.1

M3000/4000

Commands

Analog Output

Read Identification

Command

Slope

Read Setup

M3000/4000 commands are Write Protected

Low

Limit

Remote Reset $1 Setup $1 SU310701 CO Trim Maximum $1 TMX+00020.17 Trim Minimum $1 TMN+00000.95

Set

Typical Command Message

$1 ACK $1 A0+00020.00 $1 DI

HXOFFF

$1

RAO

$1 RD

$1

RHI

$1 RID $1

RLO

$1

RMS

$1

RMX

$1

RMN

$1

RS

$1

RSU

$1

WE

$1

H1+00015.00

$1

IDBOILER

$1

LO+00004.00

RR

Typical Response Message

'0007

*+00017.50 'iOOO12.34

'+00020.00

*BOILER

*+ooooo.oo

'+00004.00

'+00020.00

~+00000.00

'31

070140

'31070140

M4000 Commands RAD Read Analog Data $1 RPS Read Present Slope $1 RPS

RSL

RSV

RW

The following M4000 commands are Write Protected

MS Manual Slope $1 MS+00001

MX

MN Minimum

SL

sv

TRX Trim Readback Maximum $lTRX

TR N Trim Readback Minimum $1TRN

WT Watchdog Timer

WSL Write Slope To EEPROM $1 wsL+00100.00

Read Slope $1

Read

Starting Value $1

Read Watchdog Timer

Maximum $1 MX+00100.00

Slope $1sL+oooo1 Starting Value

RAD

RSL

RSV

$1

RW

.OO

$1

MN-00025.00

.oo

$1SV+00004.00

$1wT+00010.00

'+00012.34 '+00001 *+00001 '+00005.00 '+00010.00

.oo .oo

Command Set

Acknowledge (ACK)

The ACKnowledge command is a hand-shaking command used in conjunction with the Analog Output (AO) command.

See the Analog Output (AO) command for examples

It

is

used to confirm the data sent

of

ACK usage.

to

a

4-7

module.

Command: $lACK Response:

Command: #IACK Response:

Analog

The Analog Output analog output, whether it different ways, depending on whether the either case the analog output is specified in the standard MetraByte data format:

If

the analog output is scaled in milliamps, this particular command will direct the

M3000

an analog output immediately after the command

module performs the output function and responds with

acknowledgement that the command has been executed. The

command data before the module will execute the command. The data is acknowledged

command sequence:

Output

Command: $lA0+00010.00 Response:

to

produce 10mA.

'#

form

by

the host with the ACKnowledge (ACK) command. Here is a typical

of

(AO)

the

*

*I

ACKPA

(AO)

command is the primary command used to control the

is

current or voltage. The

'$'

t

In

this example, the '$'command prompt is used

A0

command requires the host to verify and acknowledge the

or the

A0

command can function in two

'#

command prompt

is

received by the module. The

a

'*I

to

provide a simple

is

used. In

to

obtain

Command: #I A0+00010.00 Response: '1 A0+00010.0095

The host command is echoed back along with a checksum as is true with any command when used with the

performed the A0 command. by sending

received by the module and verify that the data

the command

and

perform the A0

At this point the A0 command will be performed by the module.

an

ACK

command. This allows the host to examine the command as

data

and the checksum are correct, it directs the module to go ahead

by

sending the ACK command.

Command: $1 ACK Response:

*

'#I

command prompt. At this point the module has not

It

is

waiting for

the

host to acknowledge the command

is

correct.

If

the host is satisfied that

To

complete the sequence:

4-8

M3000/4000

If

the host determines that the data is not correct, it may

sequence by sending any valid command to the module (except for the ACK

command

of

course). Example:

USERS

MANUAL

abort

the handshaking

Command: Response:

In

this case, the host examines the response data and determines that a communi-

cations error must have occurred since the response data does not match the command data.

A0

command:

Command: Response:

This time the host verifies that the data complete

Only

The

module

ERROR (RMN)

sequence that may be generated with a M3252 0-20mA module:

the

Command: Response:

at this point will a change occur on the analog output.

output data specified in the A0 command must lie within the input range

or

message. The input range may

and Read Maximum (RMX) commands. This is atypical cornmand/response

The

task:

else the command is aborted and the module will respond with a LIMIT

#I A0+00010.00

*I

A0+00030.0097

command sequence may be aborted by simply sending a

#I

A0+00010.00

*I

A0+00010.0095

is

correct and commands the module to

$1 ACK

*

be

checked

using

the Read MiNimum

new

of

the

Command: Response:

Command:

Response:

Command:

Response:

The data in the

by

the

LO

and

ERROR. Any

MANUAL MODE error may

(See

of

the Manual Modes has priority over the A0 command, and in some cases a

A0

HI

commands. Exceeding the user-defined limits will generate a LIMIT

LO

$1

*+ooooo.oo

$1

*+00020.00

$1 ?I

$1

*

command is also checked against user-defined limits specified

and

lit

commands).

RMN

(this

is

the lower range limit)

RMX

(this

is

the upper range

A0+00025.00

LIMIT

A0+00015.00

be

ERROR

generated. See Manual Mode section for details.

(the

input

exceeded)

(data is within range)

range

has

limit)

been

Command Set

4-9

Digital Input

The

DI

command reads the status of the digital inputs and the status of the analog

output. The response to the D1 command is four hex characters representing two bytes

contains the digital input

of

Command:

Response: Command:

Response:

The first response byte gives the status of the analog output on cont rolled-rate out puts

00

01

The second byte displays the hex value of the digital input data.

Digital Inputs D12 DIl/UP* D I O/D Data Bits 2

All

ERROR MESSAGES

All

modules feature extensive errorchecking on input commands to avoid erroneous operation. Any errors detected will result in an error message and be aborted.

the

command will

Command Set

All

error messages begin with

error description. The error messages have the same format for either the ' $ ' or

#

'

prompts. For example:

?1

SYNTAX

There are nine error messages, and each error message begins with a different character. Host computer software can identify an error by the first character; it is not

necessary to read the whole string.

ERROR

"?",

followed by the channel address, a space and

4-21

'

ADDRESS

There are four CR

($OD),

is made attempt to load an address greater than

BAD CHECKSUM

This error is caused by an incorrect checksum included in the command string. The

module recognizes any two hex characters appended to a command string as a checksum. Usually communications line. Often, repeating the command solves the problem. persists, either the checksum communications channel. More reliable transmissions might be obtained by using a

lower baud rate.

COMMAND

This error occurs when acommand

results when the command is sent with lower-case letters. u ppe r-case.

ERROR

$

($24),

to

load

ASCII

ERROR

values that are illegal

and

#

($23).

an illegal address into a module with the Setup

a

BAD

The

ADDRESS

CHECKSUM error is due to noise or interference on

is

calculated incorrectly or there is a problem with the

is

for

use as a module address: NULL

ERROR will occurwhen an attempt

$7F

will also produce an error.

not recognized by the module. Often this error

(SU)

command.

If

the error

All

valid commands are

($OO),

An

the

LIMIT

A

MANUAL MODE

This error may occur when using the Analog Output commands while the output is being controlled by either

or

generated commands.

ERROR

LIMIT

the Controller Input Manual Mode. The Manual Modes have priority overthe host-

ERROR

a) the

(MN)

b)

the (HI)

c) the output is inhibited by a limit switch (see Manual Modes)

may occur when using the Analog Output

A0

data exceeds the input span range defined by the MiNirnum

and Maximum (MX) values

A0

data exceeds a limit set by the LOW Limit (LO) or Hlgh Limit

commands

(AO)

command

(AO)

or Hex Output (HX)

the

Up/Down Manual Mode

if:

4-22

M3000/4000

USERS MANUAL

PARITY

A parity errorcan only occur

a parity error results from a bit error caused by interference on the communications line. Random parity errors are usually overcome

If

too many errors occur, the communications channel may have to be improved

a slower baud rate may be used.

Aconsistent parity errorwill result

In this situation, the easiest solution may be to change the parity in the host to obtain

communication. At this point the parity in the module may be changed to the desired value with the Setup

The parity may be changed

SYNTAX

A SYNTAX caused by having

or in the wrong place. Table

VALUE ERROR

This error results when an incorrect character values can only contain decimal digits

Hex Output (HX) commands can range

ERROR

if

the module

if

the host parity does not match the module parity.

(SU)

command.

or

turned

will result if the structure

too

few or

too

4.1

off

many characters, signs or decimal points missing lists the correct syntax for all commands.

0-9.

is

setup with parity on

by

simply repeating the command.

by using Default Mode.

of

the command is not correct. This

is

used

as

Hex values used in the Setup (SU) and

from

O-F.

(see

Setup). Usually

a

numerical value. Data

or

is

AVALUE ERRORwilI begeneratedbyaM4000 command

A VALUE ERROR is generated by made to calibrate a module beyond the allowed trim range.

WRITE

All commands that write data into nonvolatile memory

accidental erasures. These commands must be preceded with a Write Enable (WE)

command or else a WRITE PROTECTED error

is

attempted while the output is slewing.

TMN

PROTECTED

and TMX commands when an attempt is

moduleifaTMN,TMX,TRN,orTRX

are

write-protected to prevent

will

result.

Chapter

5

Setup

The MetraByte modules feature a wide choice of user configurable options which gives them the flexibility

system. The user options include a choice

other parameters. The particular choice of options for a module is referred to

setup information. The setup information is loaded into the module using the Setup

SU

command stores 4 bytes contained down indefinitely

memory is implemented with

The

EEPROM

for

option selection. The module never has to be opened because all of the options are selected through the communications port. This allows the setup to be changed at any time even though the module may be located thousands of feet away from the

host computer or terminal. The setup information stored in a module

back at any time using the Read Setup command

in

the module. Once the information is stored, the module can

(1

0

has many advantages over

to

operate on virtually any computer or terminal based

(32

bits) of setup information into a nonvolatile memory

years minimum) without losing the setup data. The nonvolatile

EEPROM

Information/SetUp

of

baud rate, parity, address, and many

(SU)

so

there are no batteries to replace. DIP

switches or jumpers normally used

(RS).

Command

as

the

command. The

be

powered

may

be read

The following options can be specified by the Setup command: Channel address

Linefeeds Parity (odd, even, none)

Baud rate

Echo Communication delay Number Limits enable/disable Continuous Input enable/disable (M4000) Manual Mode enable/disable Manual Up/Down Inputs Controller Inputs Limit Switches: Normally Open/Normally Closed

Each

all

options, refer

(300

of

displayed digits

of

these options will be described in detail below. For a quick look-up chart on

(1

to

38,400)

to

Tables

24

values)

(0-6

characters)

5.1-4.

5-2

M3000/4000

USERS

MANUAL

Command

The general format for the Setup

$lSU[bytel][byte 2][byte 3][byte

A typical Setup command would

Notice that each byte is represented by its two-character example, byte 1 is described by the ASCII characters binary

hex (0-F) characters. Any deviation from this format will result in aSYNTAX Appendix A contains a convenient hex-to-binary conversion chart.

Forthe purposesof describing the SetUpcommand, ‘bit 7’ refers to the highest-order bit of a byte of data. ’Bit

The SU command is write protected to guard against erroneous changes in the setup data; therefore each SU command must be preceded by a Write Enable (WE)

command. To abort an SU command in progress, simply send a non-hex character (an

‘X’

Caution:

result in changing communications parameters (address, baud rate, parity) which will result in cases the user may have to resort

The recommended procedure examine the existing setup data before proceeding with the SU command.

Syntax

(SU)

command is:

41

look

like:

001 1 0001

’bit number’: binary data:

for

example) to generate a SYNTAX

Care must be exercised in using the

a

(31 hex). The operand

0’

refers to lowest-order bit:

7

6

5 4

0

1

loss

of

communications between the host and the module. In some

is

3210

0 0

to

using Default

to first use the Read Setup

$1

SU31070180.

of

a

SU

command must contain exactly

0

1

ERROR,

SU

Mode

ASCII

‘31’

which is the equivalent of

=$31

(hex)

and try again.

command. Improper use may

to restore the proper setups.

equivalent. In this

ERROR.

(RS)

command to to

8

Byte

1

Byte 1 contains the module (channel) address. The address code for the string character used to address the module. In our example command

$?SU31070180

sample command

‘1

’,

which in this particularcase remains unchanged. To change the module address

to

‘2’

,

byte

character command is sent, the module address

The module will no longer respond to address When using the

the new address in a place that is easily retrievable. The only way with a module with an unknown address is with the Default Mode.

The most significant bit of byte 1 (bit ASCII codes that are illegal for use as an address. These codes are

‘2’.

,

the first byte

is

sent

to

1

of

the Setup command becomes

Now the command will

SU

command to change the address

‘31’

is

a

module, the EEPROM will be loaded with the address

7)

the

ASCII

‘32’,

look

like this: $lSU32070180. When this

is

changed from

‘1’.

must be set

code for the character

which

of

to

‘0’.

is

stored as the ASCII

‘1’.

If

is

the

ASCII

‘1’

to

‘2’.

a

module,

In addition, there are four

code for the

be

sure to record

to

communicate

$00,

$OD,

our

$24,

Setup lnformation/SetUp Command

$23

which are ASCII codes for the characters

for an address will cause an

unchanged. This leaves a totaI

the SU command. It

characters be used dumb terminal. Refer to Appendix A for a list

printable

ASCII

codes that may be used as addresses.

is

($21

ADDRESS

of

124

highly recommended that only ASCII codes for printable

to

$7E)

which greatly simplifies system debugging with a

ERROR

possible addresses that can

NUL,

CR,

$,

and

and the setup data will remain

of

ASCII codes. Table

#.

Using these codes

be

loaded with

5.1

lists the

5-3

Table

5.1 Byte 1 ASCII HEX

21

22

25

26

27

28

29 2A

2B 2c

2D

ASCII

L6

Yo

'

1

*

-

2E

2F

30 31 32

33

34 355

36 37 7

38 39

I

3 4

!

&

(

+

Y

.

0

1

2

6

8 9

HEX

3A

38

3c 3D

3E

3F

40

41 A

42 43

44

45 E

46

47 48 H

49

4A

4B

4c

4D

4E

4F 50

ASCII

:

;

<

=

>

?

@

B

c

D

F

G

I

J

K

L

M N

0

P

Printable Characters.

HEX

51

52

53

54

55

56

57 58

59

5A 5B

5c 5D

5E

5F 60

61

62

63

64 65

66

67

ASCII

Q

R

s

T

u

V

w

X

Y Z

\

1

A

-

'

a

b

c

d

e

f

g

HEX

68

69

6A

6B

6C

6D

6E 6F

70

71

72 73

74 75 76 77

78

79 7A

7B

7c

7D

7E

ASCII

h

i

j

k

I

m

n

o P

9

r

s

t

u

v

w

x

Y

z

{

I

1

-

5-4

M3000/4000

Byte

2

Byte 2 is used

channel; linefeeds, parity,

Linefeeds

The most significant bit This option can be useful when using the modulewith adumb terminal. from the modules are terminated with a carriage return will generate a automatic linefeed when a carriage return is detected. However, for terminals that do not have this capability, the modules can generate the linefeed

desired. By setting after each response.

USERS

to

configure some of the characteristics

bit

of

byte 2 (bit

7

to

‘1

If

bit

MANUAL

and

baud rate.

7)

controls linefeed generation by the module.

’the module will send a linefeed

7

is

cleared

(0),

no linefeeds are transmitted.

of

(ASCII

the communications

All

responses

$OD).

Most terminals

if

$OA)

before and

When using the

ch ecksu

Parity

Bits

off.

characters transmitted by the module is set to

If

bit

output by the module is calculated as specified by bit

If

bit

If

a parity error

message. This is usually caused by noise

If

parity setup values are changed with the command will be transmitted with the old panty setup. The new parity setup becomes effective immediately after the response message from the

Baud

Bits eight values between

5

and

If

bit 5 is

5

is

6

is

Rate

0-2

rn

‘l’,

‘O’,

specify

‘#I

command prompt, the linefeed characters are not included in the

calculation.

6

select the parity

‘0l3

the panty

the parity of command strings is checked and the parity

parity is even;

is

detected by the module,

the communications baud rate.

300

to

be used by the module. Bit 5 turns the parity on and

of

the command string is ignored and the parity bit

‘1’.

6.

if

bit

6

is

‘A’,

and

38400

parity

baud. Referto Table

is

odd.

it

will respond with

on

the communications line.

SU

command, the response to the

The

baud rate can be setected from

a

SU

5.2

for the desired code.

of

characters

PARITY

command.

of

ERROR

SU

The baud rate selection is the an

SU

command.

must occur. A reset is performed by sending a Remote Reset

powering down. This extra level of write protection is necessary to ensure that communications to the module is not accidently changing the baud rate

Let’s run through an example of changing the baud rate. Assume oursample module contains the setup data value

In

order

of

only

setup

for the baud rate to be actually changed, a module reset

an

RS-232C

of

‘31 0701

data

string.

80‘.

that

lost.

Byte

is

not

implemented directly after

(FIR)

command or

This is very important when

2

is

‘07’.

By referring to the

SU

Setup Information/SetUp Command

5-5

command chart we can determine that the module and baud rate

would get:

Command: Response: ‘31

Let’s

say

‘01

0

(from Table

we must first send a Write Enable command because

Command: $1

we

300.

wish

If

we perform the Read Setup command with this module we

$1

RS

0701

80

to

change the baud rate to 9600 baud. The code for 9600 baud

5.2).

This

would change byte 2 to

WE

is

‘02’.

set for

Response: Command: $1 SU31020180

Response:

This sequence

rate of the module. The module remains in

the Read Setup

Command: $1 Response:

Notice that although the module is communicating

indicates a baud rate of 9600 (byte

send a Remote Reset

*

of

messages

(RS)

command to check the setup data:

31020180

is

done in

300

baud because that was the original baud

300

baud afterthis sequence. We can use

RS

2

=

‘02’).

To

actuallychange the baud rate to 9600,

(RR)

command (RR is write protected):

in

no

linefeeds, no panty,

To

perform the

SU

is write protected:

300

baud, the setup data

SU

command

is

Command: $1WE Response:

Command:

Response:

Up

to

this point all communications

respond to any further communications at 9600 baud. continue ope ration.

If

the module does

At

this point the host computer or terminal

*

$1

*

not

RR

respond

have

been sent at

to

the new baud rate, most likely the setup data is

300

baud because

300

baud. The module will not

it

is now running

must

be set to

9600

at

baud to

56

M3000/4000

incorrect. Try various baud rates from the host until the module responds. The last resort is to set the module to Default Mode where the baud rate

USERS

MANUAL

is

always

300.

Setting a string

tion. Refer to Chapter 3 for instructions.

Bits 3 and

These two bits of byte 2 are not used and should be set to

Table

BYTE

5.2

2

4

Byte

of

RS-232C

2:

Linefeed,

modules

Parity

to a new baud rate requires special considera-

and

Baud

Rate.

‘0’

Byte

3

This byte contains the setup information

default value for this byte is

Continuous Input

Bit 5 enables the continuous input option available set to

for more information on the continuous input option.

Limit

Bit 4 may be used to disable any limit checking

commands. Bit

‘0’.

Setting Bit

Disable

510

4

is

normally set to

‘01’.

‘1

’

enables the continuous input. Refer

for

additional communications options. The

‘0’;

Bit 4 is set to

on

limits set

M4000

‘1’

units

and

it

is

to

the

M4000

by

the

LO

and

to inhibit limit checking.

Wm

normaliy

section

HI

limit

Setup Information/SetUp Command

5-7

Echo

When bit 2 is set the communications line. This option is necessaryto ‘daisy-chain’ multiple

modules. Echo is optional cleared

to

‘0’

to

on

RS-485

‘1

’,

the module will retransmit any characters

for

systems with a single

models. See Chapter 3 for a more complete description.

RS-232C

it

has received on

RS-232C

module. Bit 2 must be

Delay

Bits 0 and 1 specify a minimum turn-around delay between a command and the module response. This delay time tocapture data from quick-responding commands such as Dt. This is particularly true for systems that use software command delays listed in the Software Considerations section unit

of

delay specified by bits 0 and

transmit one character with the baud rate specified in byte

of

delay at 300 baud is 33.3

of

delay units is selectable from

mS;

is

useful

UART’s.

1

for

38.4

0

to

6

on

host systems that are not fast enough

The specified delay is added

of

Chapter 3. Each

is

equal to the amount

kilobaud the delay is

as shown in Table 5.3.

of

time required to

2.

For example, one unit

0.26

mS. The number

to

the typical

In some systems, such as

a

linefeed

by

a

the linefeed and the module response, the module should be setup to delay by

units.

Table

(LF).

The modules will respond immediately after a command terminated

CR

and will ignore the linefeed. To avoid a communications collision between

5.3

Byte

3

Options.

IBM

BASIC,

a

carriage return

(CR)

is always followed by

2

5-8

M3000/4000

Byte

4

This setup byte specifies the number of displayed digits and the Manual Mode configuration.

Nu

m

ber

of

displayed digits

For ease common 7-digit configuration consisting of sign, 5digits, decimal point, andtwo more digits. Typical data

(digital-to-analog converter) is

resolution of the output format cases, the low-order digits

used to insert trailing zeros into the data format to limit the output resolution and mask

off

mean i ng less digits.

of

use, the data format of all MetraByte modules is standardized to a

USERS

looks

like:

MANUAL

+00100.00.

12

bits or about

is

much greaterthan the resolution

would

display meaningless information. Bits 6 and 7 are

However, best-case resolution

3

1/2

of

the

DAC

digits. In some cases, the

of

the

DAC.

In such

Bit 7 Bit

0

1 1

Manual Mode Disable

Bit 2 is normally set to output. Setting bit

Manual Mode Select

Bits 0 and 1 allow

Modes allow the analog output to

module connector. Details on Manual Modes are given in the Manual Mode section.

Table

BYTE

6

0

1

0

1

5.4

4

XXXXO.00

XXXXX.00

XXXXX.XO XXXXX.XX

‘0’

which allows the Manual Mode inputs to affect the analog

2

to

‘1

’

disables the Manual Modes.

the user to select among four different Manual Modes. Manual

Byte 4 Displayed Digits

(4

displayed digits)

(5

displayed digits)

(6

disptayed digits)

(7

displayed digits)

be

controlled

and

Manual

by

the UP* and

Mode

Select

DN*

pins

on

the

Setup InformatioiVSetUp Command

5-9

Setup Hints

Until you become completely familiar with the Setup command, the best method of

changing setups is to change one parameter at a time

has been made correctly. Attempting to modify all the setups at once can to confusion. factory setup as shown in Table

Use the Read Setup module

If

you reach’a state

(RS)

command to examine the setup information currently in the

as

a

basis for creating a new setup. For example:

of

total confusion, the best recourse is to reload the

5.5

and

try again, changing one parameter at a time.

and

to verify that the change

often

lead

Assume

be used

Read Setup command:

By referring to Table

the

representation in binary

command, use the data read

Verify

By

problems associated with incorrect setups may be identified immediately. Once a

satisfactory setup has been developed, recordthe setupvalue and use itto configure

similar modules.

you

have

a

M3000

in

adaisy-chain (See Communications). Read out the current setup with the

Command: Response:

RS

command we see that byte 3 is currently set to

0000

Command:

Response:

Command:

Response:

that

the module

using the

RS

$1

310701

5.3,

of

binary

01

01.

The new hexadecimal value of byte 3 is

$iWE

*

$fSU310705CO

*

command and changing one setup parameter at a time, any

unit

and

you wish

RS

CO

we find that the echo

0000

is

0001.

out

(SU

echoing characters and the setup

To

with the

is

write-protected)

to

set echo, bit 2 must be set to

RS

setup the unit to

is

controlled by bit

01.

command, changing only byte

echo

so

2

of

byte

This

is

the hexadecimal

‘1

’.

05.

To perform the SU

is

correct.

that it may

3.

This results

From

3:

If

you commit an error in using the Setup command, it is possible to lose communications with the module. to re-establish communications.

Table

(All

Model Setup Message

M312X1 M316X, M412X, M416X 31 0701 80 M313X1 M314X, M317X, M318X 31 0701 40

M413X, M414X, M417X, M418X 31 M325X, M425X

5.5

Factory

modules from the factory are set for address

Setups

In

this

by

case,

Model.

it may be necessary

‘l’, 300

0701

40

31

0701

CO

to

use the Default

baud, no parity)

Mode

5-10

M3000/4000

USERS

MANUAL

Setup

S3000

module setup. Contact

Software

setup

software

for

the

factory

IBM

for

PC

details.

and

compatibles

is

available to facilitate

Chapter

6

Digital

MANUAL

Each

DN*,

control inputs which influence the analog output or they may be used as general-

purpose digital inputs. The function (SU)

The inputs

logic (DI)

command. Voltage inputs less than

3.5V are read Switch closures can be read by the digital input by simply connecting the switch

between

parts

The pull-ups supply only current operation should be used. For other types

to

provide extra pull-up current with an external resistor. The resistor should be tied

between the switch and

MODES/DIGITAL

M3000/4000

DI1

/UP*,

command.

are

“1”

condition (see Figure

GND

are unnecessary.

module has three digital input connections designated as

and

012.

protected to voltages up to +30V and are normally pulled up

as

‘1

’.

terminal and a digital input. Internal pull-ups are used

INPUTS

These inputs have a dual function; they may be used

0.5mA

+V.

UO

of

6.1).

;therefore, self-wiping switches designed for

Funcions

the input pins is programmable with the Setup

Digital inputs can be read with the Digital Input

1

V

are read back as

and

of

switches, it may be necessary

Manual

‘0’.

Signals greater than

so

Mode

DIO/

as

to

the

additional

low

Digital inputs may be used offered by many manufacturers.

to

sense

AC

voltages

by

using isofated sensing modules

6-2

M3000/4000

USERS

MANUAL

Figure

MANUAL

The M3000/4000 modules may be configured to use the digital inputs to control the analog output. These functions are called Manual Modes. Four different Manual Modes may be specified:

Up/Down Controller Input

Limit Switch Limit Switch

These modes are selected by Bits 0 and section). Also, the Manual Mode Disable bit (Bit Manual Modes.

UP/DOWN

Manual Up/Down control is the standard configuration when the module is shipped

from the factory. This configuration provides a local operator interface to control the analog output value independent

moved up or down by manipulating the come from simple

Figure 6.2 shows the simplest connection. With the two switches, four different input

combinations are possible:

MODES

NO

NC

switches

or

may

6.1

Digital Inputs

1

of

Byte 4 in the Setup data. (See Setup

2,

Byte 4) must be cleared to enable

of

the host computer.

UP*

and

DN*

inputs. The control inputs

be

logicsignals originating

The

analog output

from

may

be

may

otherequipment.

UP*DN*

0 0

1 1

0

1

0

1

Hold Slope Up Slope Down

No

Action

Digital

D

I1

IU

P’

D

IWDN’

GND

I/O

Functions and Manual Mode

6-3

Figure

6.2

Manual Up/Down Control.

Since the digital inputs are pulled up internally, no connection or an open pushbutton generates a logic

generates a logic

‘1’.

Shorting the input line to ground or closing the pushbutton

‘0’.

The

‘*’

in the terminal labels indicate that the inputs are negative

true.

If

both switchesareopen, a logic

If

the

UP*

signal input is grounded

will slope up to + Full Scale. A smooth slope in the output

incrernenting the DAC approximately

grounded, the analog output will slope towards

1,l

isgeneratedand no manual action

by

closing the

1000

UP

pushbutton, the analog output

times a second.

-

Full

Scale. The analog output will

If

is

generated by

only the

is

performed.

DN*

input is

stop moving when the switches are released. The slope

on M3000 units is scaled complete. The manual slope rate value with the Manual Slope

The Manual Modes have priority over host-generated output commands. both ofthe

rate

on M3000 modules is fixed and cannot be changed. The manual slope

so

that a full-scale output change requires 5 seconds

on

M4000 units may be programmedto any desired

(MS)

command.

If

UP*

and

DN*

inputs is held low, an Analog Output

(AO)

or Hex output

to

either or

(HX)

command generated by the host will result in a MANUAL MODE error message and the host command

both input switchesare output

will

hold its present value. Any attempts by the host computer to change the

output will result

is

aborted. This brings

on.

If

both

in a

MANUAL

MODE

UP*

and

error.

us

to the fourth switch combination, when

DN*

signalsare held

at

Iogic‘O’, the analog

6-4

M3000/4000

USERS

MANUAL

Another useful switch configuration isshown in Figure the module is on-line with a host which is actively sending output commands

6.3.

This circuit is useful when

to

the

module. This circuit will lock out the host while manual operations are being

performed. Under normal host control, the ManuaVHost switch

manual operation, the toggle switch

is

closed, grounding both UP* and

is

left open.

DN*

for

inputs. This will prevent the host from controlling the analog output. The output may be controlled manually by depressing the normally-closed pushbuttons. Note that the

'UP'

button is connected to the DN* input.

NORM4LLY

PUSHBUTrONS

CLOSED

MNUAL

TOGGLE

Figure

CONTROLLER

INPUT

This Manual Mode is a variation operation with ON-OFF controllers. With this mode, a

to add an analog control output to an truth table for this mode

--

UP*

0

1 1 1

DN*

0

1

0

With this setup, the

open,

no

Manual Mode action takes place. If the signal is grounded, the controller

input is enabled and the analog output will

controlled by the UP* input. In this mode

integral

an

of

the

UP*

signal input. In orderto keep the analog output in the linear region,

external signal must be used to manipulate the UP* input. This is usually done

SWITCH

6.3

Manual Up/Down Control with Host Lock-Out.

of

the manual up/down control specifically setup for

M3000/4000

ON-OFF

or time-proportional controller. The

is:

Slope Up

No

Action

Slope Down No

Action

DN'

input

acts

as an enable signal.

slope

of

operation, the analog output value is the

up

If

the

or down. The slope direction is

unit may be used

DN*

input

is

through feedback.

high or

Digital

The slope rate used at the analog output in controller mode is the value specified for

manual slope. The slope rate programmable with the Manual Slope (MS) command.

is

fixed

on

I/O

M3000

Functions and Manual Mode

units; on M4000 units the slope is

6-5

LIMIT

Two signals to limit the analog output that may be obtained with the Analog Output command. The limit switch mode may be programmed to accommodate either

normally-open

section

Figure remain open, module operation is not affected.

attempt to decrease the analog output signal with the

LIMIT increase the analog output will be performed normally.

switch is closed, the analog output cannot be decreased from its present value with an

Conversely, attempt to increase the analog output with the A0 command will result in a LIMIT

ERROR.

If

a

SWITCHES

of

the Manual Modes allow the use of limit switches or other external digital

(NO)

for

mode selection details.

6.4

shows a typical module with normally-open limit switches.

ERROR

A0

command.

if

the Down Limit switch

The output may be decreased with no error.

both limit switches are closed, any attempt

LIMIT

ERROR.

switches or normally-closed

message and the command will be aborted. An

is

open and the

(NC)

switches.

If

the Down Limit switch is closed, an

A0

command will result in a

As

long as the Down Limit

UP

Limit switch is closed, an

to

use the

A0

command will result in

See

the Setup

If

the switches

A0

command to

(AO)

D

IllU

44-44

P+

DIWDN'

S4l

I=;a

DOWN L IMlT

I1

NQRM4LLY

TOGGLE

Figure 6.4 Using Switches to Limit Analog Output.

OPEN

SWITCHES

GND

6-6

M3000/4000

On

M4000 units with controlled output ramps, the limit switches will stop the output

even after a successful A0 command. Figure example a M4181 voltage-output module is programmed with an output slope

S.

Assume that the output voltage value is initially

$1A0+10000.00

activated before the output reaches is terminated. The limit switch condition may be read by the analog output may be read with the

USERS

will ramp the output to +1OV. However,

MANUAL

6.5

illustrates this action.

1

OV,

the output will stop and the A0 command

RD

or

RAD

commands.

OV.

The command:

if

the

UP*

limit switch

DI

command and the

In

of

this

1

V/

is

+1

OY

a-

LlMlTSW

CLOSED

OPEN

Figure

The Manual Mode setup may be configured to allow either Normally Open or Normatly

Closed

1

6.5

Using Limit Switches to Stop an Analog Output

(NC)

5

switches. The truth table for either mode is:

r---l----

/

ITCH

10

NORMAL

t

OUTPUT

Ramp.

(NO)

Inputs Action

DN*

0 0

0

1

=

Open Switch

UP*

1

0

1

NO Hold

Down Limit Up Limit

No

Limit

NC No

Limit

Up

Limit

Down

Hold

Limit

Chapter

7

Power

M3000/4000 modules may be powered with an unregulated Power-supply ripple must be limited to

ripple voltage must be maintained between the power supply specifications are referred voltage drops must be considered when the module is powered remotely.

All

M3000/4000 modules employ an on-board switching regulator to maintain

efficiency over the

inversely proportional to the line voltage. consume a maximum

1

.O

watts maximum. The power consumption figures should

the power supply current requirement. will

be

used

to

4

X

0.75

=

3 watts. The power supply must be able to provide

In somecases, asmall numberof modules may be operated by"stealing"powerfrom a host computer

232C D25 connector.

10

to

30

volt input range; therefore the actual current draw is

of

0.75

watts and M3Q00/4000 current output models consume

power four voltage output modules. The total power requirement is

or

terminal. Many computers provide

5V

peak-to-peak, and the instantaneous

10

and

to

the module connector; the effects of line

M3000/4000

For

example, assume a 24 volt power supply

a

+10

to +30Vdc supply.

30

volt limits at all times.

voltage output modules

be

used in determining

3

+

24

+15

volt output on the

Supply

=

0.1

25

All

good

amps.

RS-

Small systems may be powered by using wall-mounted calculator-type modular power supplies. These units are inexpensive and may be obtained from many retail elect ro n ics outlets.

For best reliability, modules operated on long communications lines should be powered locally using small calculator-type power units. This eliminates

the voltage drops on the Ground lead which may interfere with communications signals. In this

Ground terminal must be connected back to the host to provide a ground return for the communications

All

M3000/4000 modules are protected against power supply reversals.

case

the

loop.

V+

terminal is connected only to the local power supply.

(9500

feet)

The

Chapter

8

Troubleshooting

No

module

Assuming that the module is in a system, complete the following steps before

removing it from the system. These steps will check the obvious things before removing.

1.

Using a voltmeter, measure the power supply voltage at the module +Vs and

Ground terminals to ensure that the power supplied is between

2.

Check to see that the communications lines are connected properly and that

there are no breaks in the lines.

3.

If

you are using the RS-232C

switch

If

the above steps do not correct the problem, remove the module from the system

and return to the bench. Complete the following steps.

1.

Connect a working power supply (between

Ground terminals

is

set

response.

to

the correct position.

on

the module.

to

RS-485

+10

and +30Vdc.

converter, make sure the baud rate

+10

and +30Vdc)

to

the

Vs

and

2.

Connect the module to a dumb terminal as

Your terminal should be set the

RS-485

3.

Connect a jumper wire from the Ground terminal to the Default* terminal.

4.

Turn the power supply on, type

key.

If

the module still does not respond, call the factory for assistance.

responds, send a message

1.

Check that the baud rate is correct.

2.

If

daisy-chaining RS-232C modules, be sure that the echo bit

3.

ff

using byte time delay make sure that the proper delay procedure basically makes sure that the module and the system are speaking the same language. Reinstall

converter, make sure its baud rate

$1

RS

is

correct.

to

300

command

module

baud rate and

$1

RD on the terminal and press the Return

to

see if the information in the module's setup

in the system and try again.

in

the Quick Hook Up procedure.

no

parity. Also if you are us i n g

is

set

to

300

baud.

If

the module

is

set to

is

set. The above

1.

Chapter

9

Cali

M3000/4000 units feature state-of-the art digital trimming techniques to eliminate the need for calibration pots

commands through the communications port. The on-board microprocessor is used

to calculate calibration constants which are then stored in the nonvolatile EEPROM.

Fieldcalibration

the device.

Digital calibration is made possible by reserving a small portion trim purposes. The DAC hardware is capable of producing outputs full scale range normally accessed by the Analog Output

be demonstrated by using the Hex Output directly without trims. For example, a M3181 module has a nominal output

IOV.

The absolute maximum output of the

corn m an d

:

Command:

of

the units may be performed without the need to physically access

or

other hardware trims. Calibration

(HX)

command, which controls the DAC

$1

HXOFFF

DAC

may be obtained with the HX

is

performed with trim

of

the DAC scale for

(AO)

command. This may

bration

in

excess

of

the

0

to

Response:

A measurement

shows that

2%

of the DAC range is reserved for trim purposes.

0.2

of

the output signal would typically read about

volts is the excess DAC range available fortrimming. Typically about

+10.2

volts. This

The only equipment necessary for calibration

(0.02%

communicate to the device. Calibration is performed by comparing the ideal desired output to the actual

measured output. The ideal output is set by using the Analog Output (AO) command.

After the actual output value is measured with a calibrated meter, the actual value

is

communicated to the module with the Trim MiNimum (TMN) or Trim Maximum

(TMX) commands. The TMN command trims the

scale. After receiving a TMN or TMX command, the module compares the A0 data

to the actual output value and computes a new calibration factor to reduce the error to zero.

The actual data specified by the standard MetraByte format, in units

accurate) to monitor the output signal and a terminal or computer to

TMN

and TMX command must be presented in

of

millivolts

is

a

suitable voltmeter

-

full

scale

or

rnilliamps:

output;

or

TMX

ammeter

trims +full

9-2

M3000/4000

$1

TMX+10012.00

$1

TMX+00020.05

$1

TMN-04990.00 (-4.99V)

$1

TMN+00000.02

USERS

(10.01

(20.05mA)

(+.02mA)

MANUAL

2v)

Trim resolution is 1 LSB

Calibration Procedure-Voltage units

1)

Connect voltmeter to analog output

2)

Set the output to -full scale with Analog Output

3)

Measure the output voltage.

4)

Report the actual output value to the module with the Trim MiNimum (TMN)

command. The module will adjust the output to a new value.

5)

Check the output value

4.

6)

Set the output

7)

Measure the output voltage.

8)

Report the actual output voltage

command. The module will adjust the output value.

9>

Check the output value with the meter.

8.

To further illustrate the calibration procedure, here calibration a

to

M3181

of the DAC which

with

the meter.

+

full

scale with the Analog Output (AO) command.

to

which has an output of

is

full

scale

If

the output is not within 1 LSB,

the module with the Trim

If

the output

0

to

(AO)

1

OV:

+

4096.

command.

is

not within

is

a

typical sequence used

repeat step

Maximum

1

LSB,

repeat step

(TMX)

to

Set the output

Command:

Response:

Measure the output voltage. Inthiscase,the measuredoutput

the actual value

Command:

to

-

full

scale:

$1

A0

t

to

the module with the TMN command:

$I

+OOOOO.OO

WE

Response:

Command:

Response:

Measure the output value with the meter. The output measures

1 LSB

Now

(2.5mV).

set

the

output

Command:

to

$1

TMN-00012.00

*

+

full

scale:

$1

A0+10000.00

Response:

is

-1

2

millivolts. Report

+1

mV,

which is within

Calibration

9-3

The measured output

the Trim Maximum (TMX) command:

Command:

is

+10.123V. Report the measured output to the module with

$1

WE

Response: Command:

$lTMX+lOf23.00

Response:

The output now measures

the TMX command with the new value:

Command:

$I

+1

O.O05V,

WE

which

is

still not within specification. Repeat

Response: Command:

Response:

The output now measures 9.999V, which is within 1

Current

Modules with current outputs are trimmed in exactly the same manner as voltage

outputs with one exception. Since the current outputs are unipolar and cannot sink

current, errors will result

OmA. On 0-20mA units, - full scale trim should be performed at some small positive

value such as 0.5mA. This is done by simply using the

desired trim point:

Output Calibration

$1

TMX+10005.O0

*

LSB

(2.5mV).

if

an attempt is made to calibrate the - full scale output at

A0

command

to

output the

Command: Response:

Assume that in this case the actual output

command to report the actual output to the module:

Command: Response:

Command:

Response:

The microprocessor will calculate a trim value to force the output to the

of

0.5mA.

M4000

M4000 modules offer the ability to re-scale the input data to any desired engineering

units. This may cause problems in calibration since it may be difficult

input scaling to the output signals. In thiscase it may be easierto re-scale the M4000

to standard voltage and current ranges that may be compared directly with measured

output values. Calibration is then performed with the same procedure as described

above. After calibration, the module may

ing units with the

CALIBRATION

MN

$1

A0+00000.50(0.5mA)

*

is

measured

$1

WE

*

$1

TMN+00000.63 (actuakO.63mA)

*

be

re-scaled back

and

MX

commands.

to

be +0.63mA. Use the TMN

ideal

output

to

correlate the

to

any desired engineer-

9-4

M3000/4000

USERS

MANUAL

Analog Readback Calibration

The analog-to-digital converter

(ADC)

used for readback is trimmed independently

of the DAC. The trim commands used to calibrate the ADC are Trim Readback

MiNimum

(TRN)

and Trim Readback Maximum

(TRX).

Unipolar Ouput:

the output to - full

To Trim the

scale

with the Analog Output

ADC,

be

sure the

DAC

(AO)

output

has

been calibrated. Set

command. Then perform the

Trim Readback MiNimum command:

Command: Response:

Command:

$1

*

$1

WE

TRN

(TRN is write protected)

Response:

The microprocessor will calculate calibration values scale. The calibration factors are automatically stored in

to

fix that point on the ADC

EEPROM.

Now set the output to + full scale with the Analog Output (AO) command. Perform

the Trim Readback Maximum command:

Command:

Response:

Command:

Response:

This command fixes the maximum point

EEPROM.

$1

*

$1

*

WE

TRX

(TRX is write protected)

on

the

ADC

scale and stores the data in

For

proper ADC calibration, the analog output

must

be set exactly to the -full scale and +full scale values before using the TRN and TRX commands. unknown, they

Bipolar Ouput:

the -full scale value by using the Read MiNimum

Command:

Response:

Record the Rescale the -full scale data to

Command: Response:

Set the analog output data to

Command:

Response

may

be read back using the

RMN

To Trim the ADC, be sure the DAC output

$1

RMN

*10000.00

-full

scale data for later use.

‘0’

$1

using

WE

the

MiNimum

*

$1

MN+00000.00

*

‘0’:

$1

A0+00000.00

:

*

and

RMX

commands.

has

been calibrated. Read

(RMN)

command:

(typical data)

(MN)

command:

If

these valuesare

Perform the TRN command:

Calibration

9-5

Command: Response:

Now rescale

the

RMN

command:

Command: Response:

The

ADC

is now trimmed at -full

Trimming the

the

ADC

$1

WE

*

$1TRN

*

-full

scale value back

$1

WE

*

$1

MN-10000.00

t

at

+full

scale

to the original data

(typical

scale.

is

done in a normal fashion.

previously

data)

accessed

by

Chapter

10

M4000

The M4000 series of computer-to-analog output modules contain many intelligent enhancements not found in the

commands and contains several additional commands which take full advantage of the computational power

are

:

Programmable output slew rates Programmable data scaling

Programmable start-up values Watchdog timer True analog readback

Continuous Input

Slope

The operation of most digital to analog converters (including the only for a step function when a new output value change applications this characteristic

rate is more appropriate. In a typical system where controlled output rates are desired, precious host computer time must be

the digital

Controt

is

instantaneous subject only

to

analog converter

of

the on-board microprocessor. These additional features

M3000.

is

undesirable and a gradual controlled output slew

(DAC)

The

M4000

is

desired. That is, the analog output

to

the settling time of the device. In many

used

until the desired output

accepts all

to

continually monitor and step

is

obtained.

Features

of

the M3000

M3000)

provides

The M4000 allows the system designer to obtain controlled output slew rates automatically without host computer intervention. Programmable output slope rates

may be specified bythe userand stored in nonvolatile memory. to the

new value

each time the module is powered up. The slope rate

slope commands in units of volts per second on voltage output models and milliamps

per second on current models. Slopes may

(step output) down to of

20mA! The microprocessor in the M4000 controls the output slew rate by updating the

of

M4000

.01

rnNsecond requires more than 33 minutes

a rate

to change the output value, the output will automatically slope to the

at

the specified rate.

+00000.01

of

1000

conversions per second

The

slope value is nonvolatile and will be restored

volts or mA per second in

is

specified with write-protected

be

specified from a range

to

perform an output change

at

precise

1

ms.

If

acornmand isgiven

of

+99999.99

.01

increments. A

intervals. Slope data is

slope

of

DAC

10-2

represented in the microprocessor with high-resolution floating point numbers. Before each D-to-A conversion the slope increment

value. The new output data is then rounded

represented by the 12-bit D-to-A converter and a new output is obtained. In this

manner the DAC specified by the Analog Output (AO) command. The incremental steps obtainable from the 12-bit converter and the 1 ms conversion rate combine change appear

M3000/4000 USERS MANUAL

is

smoothly stepped until the

to

be a linear ramp.

is

added to the present output

off

to the nearest value that can be

final

output value is reached as

to

make the output

Slope

The M4000 commands that are

RPS

RSL Read Slope

SL

WSL

These commands are described in detail

manual. However, a few clarifications are necessary to fully understand the function of these commands. In the M4000 , slope data

EEPROM and RAM. The RAM (Random Access Memory) contains the working copy of

obtains the slope value used to modify the output data. RAM data may be read or written any number of times; however, RAM data is lost when the down.

The EEPROM (Electrically Erasable Programmable Read Only Memory) also stores the slope value. The EEPROM is nonvolatile and is used to store the

well as other data) when power to the module to the unit, transferred from the EEPROM to RAM where it is used by the microprocessor. The

EEPROM data may be read an unlimited number

is

Commands

Read Present Slope Slope (RAM)

Write Slope (EEPROM)

the slope data used

or

a

Remote

limited to

10,000

write cycles,

directly

by

the microprocessor.

Reset

(RR)

after

command

which

related to the slope functions are:

in

the commands section (Chapter4)

is

held in two memory areas:

It

is in

RAM

that the microprocessor

M4000

is

slope

is

data

turned

reliability

off.

When power is applied

is

performed, the slope data is

of

times; however the EEPROM

is

not guaranteed.

of

this

powered

value

(as

The Write Slope (WSL) command writes the desired slope rate into both EEPROM

and RAM. This command will satisfy most applications where the desired slope is fixed and

The Slope data in EEPROM. The

to change the slope frequently under control

slope data into RAM only, the vented. For example, a

a

motor speed controller, Under control

cycled up and down once every minute. Using the slope Commands, the host computer may specify different rates to accelerate and decelerate the motor.

Write Slope (WSL) command

does

(SL)

not change during normal operation.

command writes the slope data into RAM only and does not affect

St

command

voltage

is

used in special situations where

of

the host computer. By writing the

10,000

output M4000 may be used to provide the input to

is

cycle write limit of the

of

the host computer, the motor speed is

used twice a minute to control acceleration and

EEPROM

it

is

desirable

is

circum-

If

the

M4000 Features

10-3

deceleration, the days of operation. To overcome this limitation, the Slope (SL)command may be used

to dynamically change the slew rate. Since the SLcommand writes only to

slope data may be changed an unlimited number

The Read Present Slope This data might not match the data held in EEPROM

by the

contained in EEPROM. It may differ from the value held in RAM.

SL

command. The Read Slope

10,000

cycle write limit of the EEPROM will be exceeded within

(RPS)

RAM,

of

times.

command reads the slope datacontained

if

the slope has been altered

(RSL)

command reads the slope data

in

the

RAM.

4

Other Commands

The

M4000

be

performedwithoutaffecting

are

:

Analog Output (AO) command.

output has not reached the final value specified by a previous

command may be performed “on the fly”at any time. The output will simply ramp to the new value specified. In some cases the slope direction may change

new value.

Write Slope

be performed “on the

to the final value with the new slope specified by the

controls the

(WSL)

and Slope

fly”

DAC

output as a background function; most commands may

an outputwhich is ramping toanewvalue. Exceptions

The A0 command may be performed even

A0

command. The

to

(SL)

even

commands.

if

the output is changing. The output will simply ramp

The

WSL

and or

SL

commands may

command.

if

the

A0

reach the

Remote Reset

current condition.

Watchdog Timer

the output even description

Digital Inputs:

command and

(RR).

if

of

Watchdog Timer below.

The digital

will

The

RR

command will immediately freeze the output to its

(WT).

the output is still slewing as the result of an

affect the outputs

If

a

watchdog timeout occurs, the timer will take control

UP/DN

A0

command. See

and limit switch inputs have priority over the

if

activated. See section

on

digital inputs.

of

A0

Status Commands

The

RD

command may be used at any time to read the data being fed to the

This

is

useful when using slow slew rates to monitor the present output data.

The Digital Input (DI) command may be used output signal has reached its final value. Refer to

Manual

The

controlled by the manual to write the rate data in EEPROM. The manual slope rate is totally independent the slew rates used with the computercontrolled output (AOcommand). The manual

slope rate may

Slopes

M4000

allows

be

read back with the Read Manual Slope (RMS) command.

the user

UP/DN

fo

specify the output slew rate when the output is

inputs. The Manual Slope (MS) command

as

a

quick status check to see

DI

command in chapter 4.

DAC.

if

is

used

the

of

10-4

M3000/4000

USERS

MANUAL

INPUT

All

or milliamps. For example, the command

$1

sent to a voltage output module will tell the output to go to 20mV.

The M4000 allows the user applicationsachange in input scaling may makethedataeasierto readandinterpret.

For example, a M4000 used to control a valve actuator may be easier to

data is scaled with a range The input scaling may be changed by using the Maximum (MX) and Minimum (MN)

commands. These commands are used to assign input data values with the maximum and minimum output values obtainable from the module.

The MiNimum of the module. The actual -full

command only changes the ASCII

For

factory in units

MN command may

DATA

M3000

A0+00020.00

to a current output module tells the module to output 20mA. This command sent

example, a M4141 has a -full scale output of -1

SCALING

and M4000 modules are factory set with datavalues set in units of millivolts

to

scale the input data to any desired units. In many

use

if

of

0-1

00%

rather than 4-20mA.

to

correspond

(MN)

command assigns an input data value to the

of

millivolts

be

scale

so

that a data value

used

to change the data value corresponding to -lOV:

analog output signal is not

data

value that represents the -full scale output.

OV.

of

-1

0000.00

The module is scaled at the

-full

scale output

affected;

represents -1 OV. The

the MN

the

Command:

$IWE

Response: Command:

$1

MN+00000.00

Response:

Now, the output command:

Command: Response:

will

produce an output

The Maximum

Example:

motor speed controller. The full scale range of the M4181 is voltage input the motor speed varies from 100 to

to

turn at a specified RPM requiressome computation

data. command:

For instance, to command the motor to run at 1500 RPM requires the

(MX)

A

M4181 voltage output module is used to supply the control signal

Command: Response:

$1

A0+00000.00

*

of

-1

OV.

command assigns the data value corresponding to +full scale.

3000

RPM. To command the motor

to

obtain the correct command

$1

A0+04666.00

*

0

to

+1 OV. With this

to

a

The data

is

difficult to read and interpret.

M4000

Features

10-5

A solution

The -full scale output

The +full scale output

(MX) command:

to

this problem is to scale the input data directly in units of

Command: Response:

Command:

of

OV

is assigned the value

$1

MN+000100.00

*

of

+1

OV

is

$1

MX+03000.00

assigned the value

100

RPM with the command:

of

3000

RPM with the Maximum

RPM.

Response:

Once the endpoint values are assigned, all other data values are interpolated

linearly. Now

Command:

to

set the motor

to

1500

RPM requires the command:

$1A0+01500.00

Response:

The data is much easier

actual output voltage resulting from this command

Example:

and

at

accept data of

A valve actuator accepts a 4-20mA signal: at 4mA the valve is

20mA

the valve is fully open.

0%

open

to

interpret since

to

100%

open.

We

the

scaling is directly in units

is

+4.666 volts.

wish

to

rescale a M4251 0-20mA module to

of

fully

RPM.

closed

The

The Minimum (MN) command assigns

of

the module, which in this case is OmA.

Using the two scaling points (4mA,

we

find that OmA interpolates

of

the MN command:

Command:

Response:

The maximum scaling point

value of

100%:

Command:

Response:

The module

opening:

is

now scaled in percentage of valve opening.

Command:

Response:

In this case the M4000 module produces an output

halfway.

to

a value

$1

MN-00025.00

*

of

20mA

$1

MX+00100.00

*

$1

A0+00050.00

*

an

input data value to the - full scale output

0%)

and (ZOmA, 100%) and a bit

of

-25%.

is

straight forward

This value is used in the argument

of

computation,

and

is

assigned the input

To

set the valve to

of

12mA, opening the valve

50%

If

a

M4000

Data (RD) and Read Analog Data (RAD) commands are automatically rescaled to the new units.

module has been rescaled, the readback data obtained from the Read

10-6

The

be individually reassigned to values appropriate to the new scaling.

The starting value not affected.

Slope rate data is not affected by changes in scaling and are always in units of volts per second or milliamps per second.

The Maximum and MiNimum scaling points may be assigned to any values within

the limitations of the standard data format. Negative scalings and inverse scalings

are acceptable.

It

in the module. The output range

the output range

In

as the

unwanted lower-order digits. The number of digits displayed affects only the

RAD commands.

M3000/4000

HI

and

LO

is important

some applications, it may be necessary

described in the Setup Chapter. The number of digits should be chosen to allow

full

resolution

to

USERS

limitvalues

understand that rescaling

or

resolution.

of

the DAC

MANUAL

(if

used) are not affected

is

not affected.

(4096

counts)

by

rescaling the

only

modifies the way datais represented

It

is not possible for

to

adjust the ‘number

to

be

represented while suppressing

M4000,

the

userto alter

of

displayed digits’

and must

RD

and

STARTING

When a automatically forced with the Starting Value systems in a controlled manner. Usually the starting value is specified as a “safe” condition to protect equipment and material from damage.

The Starting Value may The SV and

WATCHDOG TIMER

M4000

of

the output signal in the event of host computer or communications failure. The

timer is preset using the Watchdog Timer

in minutes. The timer module receives a valid command, the timer

If

the timer count reaches the preset value, the output will automatically

the starting value (see SVcommand). The output the present output slope rate.

The purpose failure. The Starting Value should be programmed to provide a ‘safe’ output value

minimize damage and disruption to the system under control.

VALUE

M4000

units contain a programmable software timer to provide an orderly shutdown

module is powered up from a cold start, the analog output is

to

a

pre-determined starting value. This value may be specified

(SV)

command. This feature is useful for cold-starting

be

read back with the

RSV

commands are detailed in the command section of chapter 4.

is

continually incremented in software. Each time the M4000

Read

(WT)

command to specify a timer interval

is

cleared to zero

Starting Value (RSV) command.

and

restarted again.

be

will

slew to the starting value using

of

the Watchdog Timer is to safeguard against host

or

communications

forced to

to

During normal operation,

update the module to prevent the watchdog from reaching the timeout value. Under these conditions, the watchdog has no effect on the module output. However,

the

host system should periodically read the status or

if

the

M4000

Features

10-7

timer reaches

communications channel is inoperative and will force the output

The preset value may be read back with the Read Watchdog Timer (RWT)

command.

The WT and RWT commands are detailed in the command section.

ANALOG READBACK

The Read Data (RD) command

a

status report

module,the RDdata returnsaveryaccurate readbackoftheoutput signal. However,

the data obtained with the RD command only indicates the digital data that is being

transferred from the on-board microprocessor

as

to

whether the analog signal being produced by the DAC is correct. Fault

conditions such as shorts on voltage output modules

output models cannot

To provide a true readback of the analog output signal, the

a simple analog to digital converter (ADC) which is totally independent

The

ADC

the microprocessor. The analog data may be read back with the Read Analog Data

(RAD) command. The RAD data provides true analog readback scaled in the same units as provided with the RD command.

the

of

the

is

tied directly

preset value, the

is

contained in all

output

be

of

a

module. For a properly functioning and calibrated

detected by the RD command.

to

the analog output signal and provides readback data

M4000

assumes that the host system or

to

a

safe value.

M3000

to

the DAC. It provides no indication

and

M4000

or

open circuits on current

M4000

units

to

provide

models contain

of

the

DAC.

to

The ADC is not intended

Typical accuracy

properly,the RADcommandcan greatlyenhance the user’sconfidence level that the analog output is being produced as intended. Output fault conditions from improper

wiring or loads can

to ensure that all the circuits in the

To

utilize the

Slewing outputs decrease accuracy. First obtain a status reading with the

command. This reading gives the data value being fed to the DAC.

readback with the RAD command. This data represents the actual analog output

signal. The two data readings are scaled identically. Compare the two readings; they

should differ by

specifications,

indicate improper output loading or module

is

be

ADC

most effectively, the output should be in a steady-state condition.

less

it

is a very positive indication that the output

to

be a highly accurate measurement

about 1 %of

easily

than

detected. The A DC

1

%

of

the output signal.

full scale (see specifications). However, when used

M4000

also provides aform

module are working properly.

of

redundancy

RD

Now

obtain a

full

scale (refer to specifications).

If

the error is within

is

correct. Large errors

failure.

Appendix

A

Table decimal (Hex), and Binary. Claret

AD

"43

"A

"B

"C

"D

"E

"F

"G

"H

"I

"J

"K

"L

"M

"N

"0

"P "Q

"R

"S "T

"U

"V

"W

"X

"'t

"Z

"[

"\

0

1

2

3

4

5 6

7

8

9

10

11 12

13 14

15

16 17

18 19 20

21

22

23 24

25 26

27

28

of

ASCII

Hex

00

01

02

03

04 05

06

07

08

09

OA

OB

oc

OD

OE

OF

10 11 12 13

14 15 16 17 18 19 1A 1B

1c

00001

00001 101 00001 11 00001 11 1 0001

0001 0001 001 0

0001001 1 0001 01 0001 01 01 0001 01 10

0001 01 1 1 0001 1000

0001 1001 0001 101

0001 101 0001 1 100

characters

Binary 00000000

00000001 0000001 0 0000001

000001

000001 01 000001

000001 I1 00001001

0000101 0000101 00001 100

1

00

10

000

0

1

0

0000

0001

00

0

1

(A)

and

D

128

129 81 10000001 130 82 10000010 131 132 133 134

135 136 137 138

139 8B 10001011 140

141 142

143 8F 10001111 144

145 91 10010001 146 147 93 10010011

148

149 150 96 10010110

151 97 10010111 152 98 10011000

153

154 155

156 9C 10011100

ASCII

their equivalent values in Decimal (D), Hexa-

(")

represents Control function.

Hex Binary

80 10000000

83

10000011

84

10000100

85

10000101

86

10000110

87

10000111

88

10001000

89

10001001

8A

10001010

8C

10001100

8D

10001101

8E

10001110

90

10010000

92

10010010

94 10010100

95

10010101

99

10011001

9A

10011010

9B

10011011

Tables

AD

"1

29

30

"

-

31

32

!

33

c'

34

#

35

$

36

%

37

&

38

'

39

(

40

1

41

*

42

+

43

I

44

-

45

.

46

I

47

0

48

1 49

2

50

3

51

4

52

5

53

6 54

7

55

8

56

9

57

:

58

;

59

<

60

=

61

>

62

?

63

@

64

A 65

B 66

C

67

D

68

E

69

F

70

G

71

Hex

Binary

1D 00011101

1E 00011110 1F 00011111

20 00100000 21 00100001 22 00100010 23 00100011

24 00100100

25

00100101

26 00100110

27

00100111

28

00101000

29

00101001

2A 00101010 2B 00101011

2c 00101100

2D

00101101 2E 00101110 2F 00f01111 30 00110000 31 00110001 32 00110010

33

00110011

34 00110100

35

00110101 36 00110110 37

00110111

38

00111000

39 00111001

3A

00111010

36

00111011

3c 00111100

3D 00111101

3E 00111110

3F 00111111 40 01000000

41 01000001 42 01000010

43 01000011 44 01000100

45 01000101 46 01000110

47 01000111

D

157 158 159 160 161 162 163 164

165 166

167 168

169

170 171

172 173 174 175 176 177 178

179 180

181

182 183

184

185

186

187 188

189 190 191

192

193 194 195 196 197 198 199

Hex

Binary

9D

10011101 9E 10011110 9F 10011111 A0 10100000 A1 10100001 A2 10100010

A3

10100011 A4 10100100

A5 10100101 A6 10100110

A7 10100111 A8 10101000

A9 10101001 AA f0101010

AB 10101011 AC 10101100

AD

10101101

AE

10101110 AF 10101111 BO 10110000 B1 10110001

62

10110010

B3 10110011

B4

10110100

65

10110101

B6 10110110 B7 10110111 88 10111000

69

10111001

BA

10111010

BB

10111011

BC 10111100 8D 10111101

BE

10111110

BF 10711111

co

11000000 c1 11000001 c2 11000010

c3

11000011 c4 11000100

c5 11000101 C6 11000110

c7 11000111

AD

H

72

I

73

J

74

K

75

L

76

M

77

N

78

0

79

P

80

Q

81

R

82

S

83

T

84

u

85

V

86

W

87

x

a8

Y

89

z

90

[

91

\

92

1

93

94

-

95

'

96

a

97

b

98

c

99

d

100

e

101

f

102

g

103

h

104

i

105

j

106

k

107

I

108

rn

109

n

110

0

111

p

112

q

113

r

114

Hex

Binary

48 01001000 49 01001001

4A 01001010 4B

01001011

4c

01001100

4D 01001101

4E

01001110 4F 01001111 50

01010000 51 01010001

52

01010010 53

01010011

54

01010100

55

01010101

56

01010110 57

01010111

58 01011000

59

01011001 5A

01011010

58

01011011

5c

01011100

50

01011101

5E 01011110

5F

01011111

60

01100000 61 01100001

62

01100010

63

01100011

64

01100100

65

01100101 66

01100110

67

01100111

68

01101000

69

01101001

6A

01101010

6B

01101011

6C

01101100

6D

01101101

6E 01101110 6F

01101111

70

01110000

71 01110001 72

01110010

D

200 20

1 202 203 204

205 206 207

208

209

21

0

21 1

21

2

21 3 21

4

21

5

21

6

21

7

21 8 21

9

220 22

1

222 223 224 225

226 227

228 229

230

23

1

232

233 234 235 236

237

238 239

240

241

242

Hex

C8

c9

CA

CB

cc

CD CE

CF

DO D1

D2 03

D4

D5

D6 D7 D8 D9

DA

DB

DC

DD DE

DF

EO El

E2

E3 E4

€5

E6

E7

€8

E9

EA

EB

EC ED

EE EF FO

F1

F2

Binary 1 1001

11 001

1

11 001 100 11 001 11 001 11 11 001 11 1 101

1 101 0001 11010010

1101001 1

1

11010101 11010110

1

1101 1 101 1 001 11011010 1101 101 1 1101 1100 1101 1101 1101 11 10

1101

1 1 100000 1 11 00001 11100010 11 10001 1 11 100100 11 100101

1

11 101000 11 101001 11 101010 11 10101

11101100 11 101 101

1 1 101 1 10 11 101 11 1

11 110000

11

11 11001 0

000

001

1

001 01 0

1

001 01

101

101 01 11

1 1001 10 1

1001 1 1

110001

1

101

0

1

0000

01

00

1000

11

1

A4

M3000/4000

A

D

s

115 73 01110011

t

116 74 01110100

u

117 75 01110101

v

118

w

119

x

120

y

121 79 01111001

z

122

{

123

I

124 7C 01111100

}

125

-

126 127

Hex

76

77 78

7A

78

7D

7E

7F

Binary

01110110 01110111 01111000

01111010' 01111011

01111101 01111110

01111111

USERS

MANUAL

D

243 244

245

246 247 248

249

250

251 252 253 254

255

Hex

F3

F4 11110100

F5

F6 11110110 F7 11110111

F8

F9 11111001

FA

FB 11111011 FC 11111100

FD

FE

FF

Binary

11110011 11110101

11111000 111t1010

11111101 11111110

11111111

Appendix

B

Specifications Analog Output

Single channel analog output. Voltage:

Current: Output isolation

12-bit output resolution. Accuracy (Integral Zero drift: *3OpV/OC (Voltage Output), Span tempco: *50ppmPC

1000

Settling Time to Output Slewing Manual Mode

Programmable Output Slew Rate: Current Output Voltage Compliance: 12V.

Voltage Output Drive Current:

conversions per second.

Output Protection:

(@

0-1

V,

fl

0-20mA,

+25%

V,

4-20mA.

to

and nominal power supply voltage).

0-5V,

500V

&

EN,

0-1

OV,

rms.

Differential Nonlinearity):

ma.

0.1

%FS

300pS

typ

(-FS

to

O.OlV/S

5mA

24OVAC

(current output), k30V (voltage outputs).

min,

M3000/4000

fl

OV.

0.1

21

.OclA/”C

(1

mS

max).

+FS):

5s.

(mA/S)

1

OmA

ma.

Specifications

%FSR

(Current Output).

to

(max).

lO,OOOV/S

(mA/S).

Analog

8-bit Analog Accuracy over Temperature

Digital

8-bit CMOS microcomputer.

Digital scaling and calibration.

Nonvolatile memory eliminates pots and switches.

Programmable data scaling (M4000).

Programmable High/Low output limits.

Programmable initial value

Programmable watchdog timer provides orderly shut-down in the event

host failure

Output

to

(M4000)-

Readback

Digital Converter.

(-25

(M4000).

to

+70°C):

-

2.0%FS

max.

of

B-2

M3000/4000

USERS

MANUAL

Digital

Communications

-

*

Power

Requirements: Unregulated +1 OV to +30Vdc, Internal switching regulator.

Protected against power supply reversals.

inputs

Voltage levels: +30V without damage.

Switching levels: High, 3.5V min., Low, 1 .OVmax.

InternaI pull up resistors for direct switch input.

RS-232C, Up to

User selectable channel address.

Selectable baud rates:

ASCII

Can be used with "dumb" terminal.

Parity: odd, even, none.

All

communications setups (address, baud rate, parity) stored in nonvolatile

memory using

Checksum

Communications distance up to 10,000 feet.

RS-485.

124

multidrop modules per host communications

300,

600, 1200,2400, 4800,9600,19200,38400.

format commandhesponse protocol.

EEPROM.

can

be

added

max

(Current Output).

to

any command

or

response.

0.75W

port.

ma

(Voltage Output), 1

.OW

Environmental

Temperature Range: Operating -25OC to

Storage -25°C to

Relative Humidity:

Mechanical & Dimensions

Case: Connectors: Screw terminal barrier plug (supplied).

ABS

with captive mounting hardware.

0

to

95%

noncondensing.

+70°C.

+85OC.

Specifications are subject to change without notice. All Keithley trademarks and trade names are the property of Keithley Instruments, Inc. All other

trademarks and trade names are the property of their respective companies.

Keithley Instruments, Inc. 28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • Fax: 440-248-6168

1-888-KEITHLEY (534-8453) • www.keithley.com

Sales Offices: BELGIUM: Bergensesteenweg 709 • B-1600 Sint-Pieters-Leeuw • 02-363 00 40 • Fax: 02/363 00 64

CHINA: Yuan Chen Xin Building, Room 705 • 12 Yumin Road, Dewai, Madian • Beijing 100029 • 8610-6202-2886 • Fax: 8610-6202-2892 FINLAND: Tietäjäntie 2 • 02130 Espoo • Phone: 09-54 75 08 10 • Fax: 09-25 10 51 00 FRANCE: 3, allée des Garays • 91127 Palaiseau Cédex • 01-64 53 20 20 • Fax: 01-60 11 77 26 GERMANY: Landsberger Strasse 65 • 82110 Germering • 089/84 93 07-40 • Fax: 089/84 93 07-34 GREAT BRITAIN: Unit 2 Commerce Park, Brunel Road • Theale • Berkshire RG7 4AB • 0118 929 7500 • Fax: 0118 929 7519 INDIA: Flat 2B, Willocrissa • 14, Rest House Crescent • Bangalore 560 001 • 91-80-509-1320/21 • Fax: 91-80-509-1322 ITALY: Viale San Gimignano, 38 • 20146 Milano • 02-48 39 16 01 • Fax: 02-48 30 22 74 JAPAN: New Pier Takeshiba North Tower 13F • 11-1, Kaigan 1-chome • Minato-ku, Tokyo 105-0022 • 81-3-5733-7555 • Fax: 81-3-5733-7556 KOREA: 2FL., URI Building • 2-14 Yangjae-Dong • Seocho-Gu, Seoul 137-888 • 82-2-574-7778 • Fax: 82-2-574-7838 NETHERLANDS: Postbus 559 • 4200 AN Gorinchem • 0183-635333 • Fax: 0183-630821 SWEDEN: c/o Regus Business Centre • Frosundaviks Allé 15, 4tr • 169 70 Solna • 08-509 04 679 • Fax: 08-655 26 10 SWITZERLAND: Kriesbachstrasse 4 • 8600 Dübendorf • 01-821 94 44 • Fax: 01-820 30 81 TAIWAN: 1FL., 85 Po Ai Street • Hsinchu, Taiwan, R.O.C. • 886-3-572-9077• Fax: 886-3-572-9031

Printed in the U.S.A.

4/02

Tektronix M3000,M4000 Series Computer To Analog Output Interfaces User's Manual 64990A User manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Safety Precautions

Terminal Designations

RS-232C

Multi-party Connection

RS-485

ERROR MESSAGES

Setup Hints

WATCHDOG TIMER

ANALOG READBACK