Rockwell Automation 1771-IR, D17716.5.76 User Manual

RTD Input Module
Cat. No. 1771-IR Series B

User Manual

Important User Information

Because of the variety of uses for this product and because of the differences
between solid state products and electromechanical products, those responsible
for applying and using this product must satisfy themselves as to the
acceptability of each application and use of this product. For more information,
refer to publication SGI–1.1 (Safety Guidelines For The Application,
Installation and Maintenance of Solid State Control).

The illustrations, charts, and layout examples shown in this manual are intended
solely to illustrate the text of this manual. Because of the many variables and
requirements associated with any particular installation, Allen–Bradley
Company cannot assume responsibility or liability for actual use based upon the
illustrative uses and applications.

No patent liability is assumed by Allen–Bradley Company with respect to use of
information, circuits, equipment or software described in this text.

Reproduction of the contents of this manual, in whole or in part, without written
permission of the Allen–Bradley Company is prohibited.

Throughout this manual we make notes to alert you to possible injury to people
or damage to equipment under specific circumstances.

WARNING: Tells readers where people may be hurt if procedures
are not followed properly.

CAUTION: Tells readers where machinery may be damaged or
economic loss can occur if procedures are not followed properly.

Warnings and Cautions:

- Identify a possible trouble spot.

- Tell what causes the trouble.

- Give the result of improper action.

- Tell the reader how to avoid trouble.

Important: We recommend you frequently backup your application programs
on appropriate storage medium to avoid possible data loss.



1991 Allen-Bradley Company

PLC is a registered trademark of Allen-Bradley Company

, Inc.

, Inc.

Table of Contents

Important User Information

. . . . . . . . . . . . . . . . . . . . . . . .

Using This Manual 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Purpose
Audience 11
Vocabulary 11
Manual Organization 11
Warnings and Cautions 12
Related Products 12
Product
Related

of Manual

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Compatibility
Publications

11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Overview of the RTD Input Module 21. . . . . . . . . . . . . . . . . . .

Chapter
Module Description 21
Features
How Analog Modules Communicate with Programmable Controllers 22

Accuracy 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Getting Started 23
Chapter Summary 23

Objectives

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

of the Input Module

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

21. . . . . . . . . . . . . . . . . . . . . . . . . . . .

I

Installing the RTD Input Module 31. . . . . . . . . . . . . . . . . . . . .

Chapter
Before Y
Electrostatic Damage 31
Power Requirements 32
Module
Module Keying 32
Connecting Wiring 33
Grounding
Installing
Interpreting the Indicator Lights 36
Chapter Summary 36

Module

Chapter
Block Transfer Programming 41
PLC-2 Program Example 42
PLC-3 Program Example 44
PLC-5 Program Example 46
Module Scan Time 47

Objectives

ou Install Y

Location in the I/O Chassis

the Input Module

the Input Module

our Input Module 31. . . . . . . . . . . . . . . . . . . . . .

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Programming

Objectives

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31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

32. . . . . . . . . . . . . . . . . . . . . . .

35. . . . . . . . . . . . . . . . . . . . . . . . . . . .

35. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

41. . . . . . . . . . . . . . . . . . . . . . . . . . . .

41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table of Contentsii

Chapter Summary 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Module Configuration 51. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter
Configuring Your RTD Module 51
Data Format 52
RTD Type 52
Units of Measure 52
Real T
Configuring Block for a Block Transfer Write 54
Bit/Word Descriptions 55
Default Configuration for the R
Chapter Summary 56

Objectives

. . . . . . . . . . . . . . . . . . . . . . . . . . .

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ime Sampling

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TD Input Module

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

56. . . . . . . . . . . . . . .

Module Status and Input Data 61. . . . . . . . . . . . . . . . . . . . . .

Chapter
Reading
Chapter Summary 63

Objectives

Data from the R

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TD Module 61. . . . . . . . . . . . . . . . . . . . . . .

Module Calibration 71. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter
Tools and Equipment 71
Calibrating your Input Module 71
About Auto-calibration 71
Performing Auto-calibration 72
Performing
Chapter Summary 78

Objective

Manual Calibration

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

71. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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75. . . . . . . . . . . . . . . . . . . . . . . . . .

Troubleshooting 81. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter
Diagnostics Reported by the Module 81
Chapter Summary 83

Objective

81. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Specifications A-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Programming Examples B1. . . . . . . . . . . . . . . . . . . . . . . . . . .

Sample Programs for the R
PLC-2 Family Processors B1
PLC-3 Family Processors B3
PLC-5 Family Processors B4

TD Input Module

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B1. . . . . . . . . . . . . . . . .

Table of Contents iii

Data Table Formats C1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4-Digit Binary Coded Decimal (BCD) C1. . . . . . . . . . . . . . . . . . . . . .

Signed-magnitude Binary C2
Two's Complement Binary C3

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Block Transfer (Mini-PLC-2 and PLC-2/20 Processors) D1. .

Multiple GET Instructions - Mini-PLC-2 and PLC-2/20 Processors D1

Setting the Block Length (Multiple GET Instructions only) D4. . . . . . . .

2 and 4-Wire RTD Sensors E1. . . . . . . . . . . . . . . . . . . . . . . .

About 2 and 4-Wire Sensors E1. . . . . . . . . . . . . . . . . . . . . . . . . . .

Connecting 4-Wire Sensors E2

. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Differences Between Series A and Series B

RTD Input Modules F1. . . . . . . . . . . . . . . . . . . . . . . . . . .

Major

Dif

ferences between Series F1. . . . . . . . . . . . . . . . . . . . . . . .

Using This Manual

Chapter

Purpose of Manual

Audience

Vocabulary

Manual Organization

This manual shows you how to use your RTD input module with an
Allen–Bradley programmable controller. It helps you install, program,
calibrate, and troubleshoot your module.

You must be able to program and operate an Allen–Bradley programmable
controller (PLC) to make efficient use of your input module. In particular, you
must know how to program block transfer instructions.

We assume that you know how to do this in this manual. If you do not, refer to
the appropriate PLC programming and operations manual before you attempt to
program this module.

In this manual, we refer to:

The RTD input module as the “input module”

The Programmable Controller, as the “controller.”

This manual is divided into eight chapters. The following chart shows each
chapter with its corresponding title and a brief overview of the topics covered in
that chapter.

Chapter Title Topics Covered

2 Overview of the Input Module Description of the module, including general and hardware features

3 Installing the Input Module Module power requirements, keying, chassis location

Wiring of field wiring arm

4 Module Programming How to program your programmable controller for these modules

Sample programs

5 Module Configuration Hardware and software configuration

Module write block format

6 Module Status and Input Data Reading data from your module

Module read block format

7 Module Calibration How to calibrate your module

8 Troubleshooting Diagnostics reported by the module

11

Chapter 1

Using This Manual

Chapter Topics CoveredTitle

Appendix A Specifications Your module's specifications

Appendix B Programming Examples

Appendix C Data Formats Information on BCD, signed magnitude (12-bit) binary, and 2's

complement binary

Appendix D Block Transfer with Mini-PLC-2

Appendix E 2 and 4-wire RTD Sensors Shows wiring connections for 2 and 4-wire sensors

Appendix F Differences Between Series A

Warnings and Cautions

How to use GET-GET instructions for block transfer with Mini-PLC-2

and Mini-PLC-2/20

and B

and Mini-PLC-2/20 processors

Identifies major differences between the series A version and the
series B version of the RTD module.

This manual contains warnings and cautions.

WARNING: A warning indicates where you may be injured if you
use your equipment improperly.

CAUTION: Cautions indicate where equipment may be damaged
from misuse.

You should read and understand cautions and warnings before performing the
procedures they precede.

Related Products

Product Compatibility

12

You can install your input module in any system that uses Allen–Bradley
programmable controllers with block transfer capability and the 1771 I/O
structure.

Contact your nearest Allen–Bradley office for more information about your
programmable controllers.

This input module can be used with any 1771 I/O chassis. Communication
between the discrete analog module and the processor is bidirectional. The
processor block–transfers output data through the output image table to the
module and block–transfers input data from the module through the input image
table. The module also requires an area in the data table to store the read block
and write block data. I/O image table use is an important factor in module
placement and addressing selection. The module’s data table use is listed in the
following table.

Chapter 1

Using This Manual

Table 1.A
Compatibility

and Use of Data T

Use of Data Table

Catalog
Number

1771-IR
Series

A

= Compatible with 1771-A1, A2, A4 chassis.
B = Compatible with 1771-A1B, A2B, A3B, A4B chassis.
Y

es = Compatible without restriction
No = Restricted to complementary module placement

Input Output Read Write
Image Image Block Block
Bits Bits Words Words

8 8 8/9 14/15 Ye s Yes Ye s

B

able

Compatibility

Addressing Chassis
1/2 -slot 1-slot 2-slot

Series

A and B

You can place your input module in any I/O module slot of the I/O chassis. You
can put:

two input modules in the same module group

an input and an output module in the same module group.

Do not put the module in the same module group as a discrete high density
module unless you are using 1 or 1/2 slot addressing. Avoid placing this module
close to AC modules or high voltage DC modules.

Related Publications

For a list of publications with information on Allen–Bradley programmable
controller products, consult our publication index SD499.

13

Chapter

Overview of the RTD Input Module

Chapter 2

2

Chapter Objectives

Module Description

Features of the Input Module

This chapter gives you information on:

features of the input module

how an input module communicates with programmable controllers

The RTD input module is an intelligent block transfer module that interfaces
analog input signals with any Allen–Bradley programmable controllers that
have block transfer capability. Block transfer programming moves input data
words from the module’s memory to a designated area in the processor data
table in a single scan. It also moves configuration words from the processor data
table to module memory.

The input module is a single slot module and requires no external power supply.
After scanning the analog inputs, the input data is converted to a specified data
type in a digital format to be transferred to the processor’s data table on request.
The block transfer mode is disabled until this input scan is complete.
Consequently, the minimum interval between block transfer reads (50ms) is the
same as the total input update time for each analog input module.

The RTD input module senses up to 6 RTD signals at its inputs and converts
them to corresponding temperature or resistance in 4–digit BCD or 16–bit
binary format.

Module features include:

Six resistance temperature detector inputs

Reports oC, oF, or ohms for 100 ohm platinum or 10 ohm copper sensors

Reports ohms for other types of sensors

software configurable

0.1 degree/10 milliohm input resolution

auto–calibration

open wire detection
The module can be configured for 100 ohm platinum or 10 ohm copper RTDs,

or other sensor types such as 120 ohm nickel RTDs. Temperature ranges are
available in degrees C or F. Values can also be measured in ohms.

When using 10 ohm copper RTDs, it is necessary to dedicate your module for
exclusive use with 10 ohm copper RTDs. You can configure the module to
accept signals from any combination of 100 ohm platinum and other types of
non–copper RTDs. Both cases are determined by block transfer write (BTW)
selection.

21

Chapter 2

Overview of the RTD Input Module

How Analog Modules Communicate with Programmable Controllers

RTD

2

The processor transfers data to and from the module using block transfer write
(BTW) and block transfer read (BTR) instructions in your ladder diagram
program. These instructions let the processor obtain input values and status
from the module, and let you establish the module’s mode of operation (figure

2.1).

1. The processor transfers your configuration data and calibration values to

the module using a block transfer write instruction.

2. External devices generate analog signals that are transmitted to the

module.

Figure 2.1
Communication

3

18
16
1

4
12
10

8
6
4
2

BTW 1

BTR 4

Between Processor and Module

5

Memory

User Program

To

Output Devices

6

22

RTD Input Module

1771-IR Series B

3. The module converts analog signals into binary or BCD format, and

4. When instructed by your ladder program, the processor performs a read

5. The processor and module determine that the transfer was made without

6. Your ladder program can use and/or move the data (if valid) before it is

PC Processor

(PLC-5/40 Shown)

12933-I

stores theses values until the processor requests their transfer.

block transfer of the values and stores them in a data table.

error, and that input values are within specified range.

written over by the transfer of new data in a subsequent transfer.

Chapter 2

Overview of the RTD Input Module

7. Your ladder program should allow write block transfers to the module only

when enabled by the operator at power–up.

Accuracy

Getting Started

The accuracy of the input module is described in Appendix A.

Your input module package contains the following items. Please check that each
part is included and correct before proceeding.

RTD Input Module
Cat. No. 1771–IR Series B

User’s Manual

Chapter Summary

Input Module Field Wiring Arm User's Manual

1771-IR

Series B Cat. No. 1771-WF

In this chapter you read about the functional aspects of the input module and
how the module communicates with programmable controllers.

1771-6.5.76

23

Chapter

Installing the RTD Input Module

3

Chapter Objectives

Before You Install Your Input Module

Electrostatic Damage

This chapter gives you information on:

calculating the chassis power requirement

choosing the module’s location in the I/O chassis
keying a chassis slot for your module
wiring the input module’s field wiring arm
installing the input module

Before installing your input module in the I/O chassis you must:

Action required: Refer to:

Calculate the power requirements of all modules in each
chassis.

Determine where to place the module in the I/O chassis. Module Location in the I/O Chassis

Key the backplane connector in the I/O chassis. Module Keying

Make connections to the wiring arm. Connecting Wiring and Grounding

Electrostatic discharge can damage semiconductor devices inside this module if
you touch backplane connector pins. Guard against electrostatic damage by
observing the following warning:

Power Requirements

CAUTION: Electrostatic discharge can degrade performance or
cause permanent damage. Handle the module as stated below.

Wear an approved wrist strap grounding device when handling the module.
Touch a grounded object to rid yourself of electrostatic charge before

handling the module.
Handle the module from the front, away from the backplane connector. Do

not touch backplane connector pins.
Keep the module in its static–shield bag when not in use, or during shipment.

31

Chapter 3

Installing the RTD Input Module

Power Requirements

Module Location in the I/O Chassis

Your module receives its power through the 1771 I/O chassis backplane from
the chassis power supply. The maximum drawn by the RTD module from this
supply is 850mA (4.2 Watts).

Add the listed value to the requirements of all other modules in the I/O chassis
to prevent overloading the chassis backplane and/or backplane power supply.

Place your module in any slot of the I/O chassis except for the extreme left slot.
This slot is reserved for processors or adapter modules.

Group your modules to minimize adverse affects from radiated electrical noise
and heat. We recommend the following.

Group analog input and low voltage DC modules away from AC modules or
high voltage DC modules to minimize electrical noise interference.

Do not place this module in the same I/O group with a discrete high–density
I/O module when using 2–slot addressing. This module uses a byte in both
the input and output image tables for block transfer.

After determining the module’s location in the I/O chassis, connect the wiring
arm to the pivot bar at the module’s location.

Module Keying

Use the plastic keying bands, shipped with each I/O chassis, for keying the I/O
slot to accept only this type of module.

The input module is slotted in two places on the rear edge of the circuit board.
The position of the keying bands on the backplane connector must correspond
to these slots to allow insertion of the module. You can key any connector in an
I/O chassis to receive this module except for the leftmost connector reserved for
adapter or processor modules. Place keying bands between the following
numbers labeled on the backplane connector (Figure 3.1):

Between 10 and 12

Between 28 and 30

You can change the position of these bands if subsequent system design and
rewiring makes insertion of a different type of module necessary. Use
needlenose pliers to insert or remove keying bands.

32

Figure 3.1

Positions for the RTD Input Module

Keying

Keying Bands

Chapter 3

Installing the RTD Input Module

2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36

Between 10 and 12
Between 28 and 30

Connecting Wiring

Upper Connector

12934

Connect your I/O devices to the field wiring arm shipped with the module (see
Figure 3.2). Attach the field wiring arm to the pivot bar at the bottom of the I/O
chassis. The field wiring arm pivots upward and connects with the module so
you can install or remove the module without disconnecting the wires.

The wiring arms are specific to the input module. The RTD input module uses
field wiring arm cat. no. 1771–WF.

Use the inputs in numerical sequence from 1 to 6. Unused inputs that are left
open cause the module to report an open input condition. To avoid this, tie all
three terminals of the open channel together. Wiring connections are shown in
Figure 3.2.

The module requires three–conductor shielded cable for signal transmission
from RTD devices. This cable consists of three insulated conductors, covered
along their entire length by a foil shield and encased in plastic. The shield
reduces the effect of induced noise at any point along the cable. In order to do
this, the shield must cover the enclosed wires as completely as possible.

33

Chapter 3

Installing the RTD Input Module

Figure 3.2
Connection

RTD

Diagram for RTDs

Chassis
Ground

18

16

14

12

10

Terminal

Identification

C

Channel 1

B
A
C

Channel 2

B
A
C

Channel 3

B
A

8

6

4

2

C
B
A
C
B
A
C
B
A

Channel 4

Channel 5

Channel 6

34

12935

Most importantly, you must ground the shield at the chassis end only. We
recommend connecting each input cable’s shield to a properly grounded
common bus.

Refer to Appendix E for 2–wire and 4–wire RTD connections.
Cable impedance –– Since the operating principle of the RTD module is based

on the measurement of resistance, you must take special care in selecting your
input cables. Select a cable that has a consistent impedance throughout its entire
length. We recommend Belden 9533 or equivalent. As cable length is directly
related to overall cable impedance, keep input cables as short as possible by
locating your I/O chassis as near the RTD sensors as I/O module considerations
permit. Keep the cable free of kinks and nicks to the shielding material.

Maximum cable length is limited by an overall cable impedance of 10 ohms on
a single wire. This recommendation is based on considerations of signal
degradation due to resistance mismatch between the three conductors within the
cable.

Chapter 3

Installing the RTD Input Module

Grounding the Input Module

When using shielded cable, ground the foil shield and drain wire only at one
end of the cable. We recommend that you wrap the foil shield and drain wire
together and connect them to a chassis mounting bolt (Figure 3.3). At the
opposite end of the cable, tape exposed shield and drain wire with electrical tape
to insulate it from electrical contact.

Figure 3.3

Grounding

Cable

Ground Shield at

I/O chassis

mounting bolt

Installing the Input Module

Shield and drain

twisted into

single strand

Field Wiring Arm

Refer to Wiring and Grounding Guidelines, publication 1770-4.1 for additional information.

17798

When installing your module in an I/O chassis:

1. First, turn off power to the I/O chassis:

WARNING: Remove power from the 1771 I/O chassis backplane

and wiring arm before removing or installing an I/O module.

Failure to remove power from the backplane could cause injury or
equipment damage due to possible unexpected operation.

Failure to remove power from the backplane or wiring arm could
cause module damage, degradation of performance, or injury.

35

Chapter 3

Installing the RTD Input Module

2. Place the module in the plastic tracks on the top and bottom of the slot that

guides the module into position.

3. Do not force the module into its backplane connector. Apply firm even

pressure on the module to seat it properly.

4. Snap the chassis latch over the top of the module to secure it.

5. Connect the wiring arm to the module.

Interpreting the Indicator Lights

The front panel of the input module contains a green RUN and a red FLT (fault)
indicator (Figure 3.4). At power–up, the green and red indicators are on. An
initial module self–check occurs. If there is no fault, the red indicator turns off.
The green indicator will blink until the processor completes a successful write
block transfer to the module. If a fault is found initially or occurs later, the red
FLT indicator lights. Possible module fault causes and corrective action are
discussed in Chapter 8, Troubleshooting.

Figure 3.4
Diagnostic

Indicators

RTD

INPUT

RUN

FLT

Chapter Summary

36

In this chapter you learned how to install your input module in an existing
programmable controller system and how to wire to the field wiring arm.

Module Programming

Chapter

Chapter Objectives

Block Transfer Programming

In this chapter, we describe

Block Transfer programming

Sample programs in the PLC–2, PLC–3 and PLC–5 processors

Module scan time issues

Your module communicates with the processor through bidirectional block
transfers. This is the sequential operation of both read and write block transfer
instructions.

The block transfer write (BTW) instruction is initiated when the analog module
is first powered up, and subsequently only when the programmer wants to write
a new configuration to the module. At all other times the module is basically in
a repetitive block transfer read (BTR) mode.

The following example programs accomplish this handshaking routine. These
are minimum programs; all rungs and conditioning must be included in your
application program. You can disable BTRs, or add interlocks to prevent writes
if desired. Do not eliminate any storage bits or interlocks included in the sample
programs. If interlocks are removed, the program may not work properly.

Your analog input module will work with a default configuration of all zeroes
entered in the configuration block. See the configuration default section to
understand what this configuration looks like. Also, refer to Appendix B for
example configuration blocks and instruction addresses to get started.

Your program should monitor status bits (such as overrange, underrange) and
block transfer read (BTR) activity.

The following example programs illustrate the minimum programming required
for communication to take place.

41

Chapter 4

e

e

Module Programming

PLC-2 Program Example

Note that PLC–2 processors that do not have the block transfer instruction must
use the GET–GET block transfer format which is outlined in Appendix D.

Figure 4.1

Family Sample Program Structure

PLC-2

XXX
XXX
XXX

XXX

Enable

EN

17

Done

DN

15

Storag

Bit A

L

Storag

Bit A

U

Storage

Bit B

L

Block Transfer
Read Done Bit

1

Pushbutton

2

Block Transfer Write

Done Bit

3

Block Transfer Write

Done Bit

4

FILE TO FILE MOVE
COUNTER ADDR:
POSITION:
FILE LENGTH:
FILE A:
FILE R:
RATE PER SCAN:

1

Pushbutton

YYYY-XXXX

XXX-XXX

Block Transfer Read

Done Bit

5

Storage

Power-up Bit

6

Storage

Bit B

Power-up

Bit

7

Storage

Bit A

1

Y

ou can replace the pushbutton with a timer "done" bit to initiate the block transfer

write on a timed basis. You can also use any storage bit in memory

Bit A

Storage

Bit B

Power-up Bit

BTR Done Bit

BLOCK XFER READ
DATA ADDR:
MODULE ADDR:
BLOCK LENGTH:
FILE:

BLOCK XFER WRITE
DATA ADDR:
MODULE ADDR:
BLOCK LENGTH:
FILE:

XXX

RGS

XX

XXXX:XXXX

XXX

RGS

XX

XXXX:XXXX

.

Storage

Bit B

U

Enable

EN

Done

DN

Enable

EN

Done

DN

X7

X7

X6

X6

42

Chapter 4

Module Programming

Program Action

Rung 1 - Block transfer read buffer: the file–to–file move instruction

holds the block transfer read (BTR) data (file A) until the processor
checks the data integrity.

1. If the data was successfully transferred, the processor energizes the BTR

done bit, initiating a data transfer to the buffer (file R) for use in the
program.

2. If the data is corrupted during the BTR operation, the BTR done bit is not

energized and data is not transferred to the buffer file. In this case, the data
in the BTR file will be overwritten by data from the next BTR.

Rungs 2 and 3 - These rungs provide for a user–initiated block transfer
write (BTW) after the module is initialized at power–up. Pressing the
pushbutton locks out BTR operation and initiates a BTW that configures
the module. Block transfer writes will continue for as long as the
pushbutton remains closed.

Rungs 4 and 5 - These rungs provide a ”read–write–read” sequence to the
module at power–up. They also insure that only one block transfer (read
or write) is enabled during a particular program scan.

Rungs 6 and 7 - These rungs are the conditioning block transfer rungs.
Include all the input conditioning shown in the example program.

43

Chapter 4

Module Programming

PLC-3 Program Example

Block transfer instructions with the PLC–3 processor use one binary file in a
data table section for module location and other related data. This is the block
transfer control file. The block transfer data file stores data that you want
transferred to the module (when programming a block transfer write) or from
the module (when programming a block transfer read). The address of the block
transfer data files are stored in the block transfer control file.

The industrial terminal prompts you to create a control file when a block
transfer instruction is being programmed. The same block transfer control file
is used for both the read and write instructions for your module. A different
block transfer control file is required for every module.

A sample program segment with block transfer instructions is shown in
Figure 4.2, and described below.

Figure 4.2

Family Sample Program Structure

PLC-3

1

Pushbutton

2

Block T

ransfer

Read Done Bit

Power-up

Bit

Block T

ransfer

rite Done Bit

W

BTR
BLOCK XFER READ
RACK:
GROUP:
MODULE:
DATA:
LENGTH:
CNTL:

BTW
BLOCK XFER WRITE
RACK:
GROUP:
,MODULE:
DATA:
LENGTH:
CNTL:

X = XXXX

XXXX:XXXX

XXXX:XXXX

X = XXXX

XXXX:XXXX

XXXX:XXXX

XXX

XXX

X

X

X

X

ENABLE

EN

12

DONE

DN

15

ERROR

ER

13

ENABLE

EN

02

DONE

DN

05

ERROR

ER

03

44

Program Action

At power–up, the user program examines the BTR done bit in the block transfer
read file, initiates a write block transfer to configure the module, and then does
consecutive read block transfers continuously. The power–up bit can be
examined and used anywhere in the program.

Rungs 1 and 2 - Rungs 1 and 2 are the block transfer read and write
instructions. The BTR enable bit in rung 1, being false, initiates the first
read block transfer. After the first read block transfer, the module
performs a block transfer write and then does continuous block transfer
reads until the pushbutton is used to request another block transfer write.