Allen-Bradley 1771-IXHR User manual

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High Resolution
Thermocouple/Millivolt Input Module
Cat. No. 1771-IXHR
User Manual
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1

1991 Allen-Bradley Company , Inc.
PLC is a registered trademark of Allen-Bradley Company , Inc.
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.
Important User Information
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Important User Information 1. . . . . . . . . . . . . . . . . . . . . . . .
Using This Manual 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Purpose of Manual 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Audience 11
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vocabulary 11
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Manual Organization 11
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Warnings and Cautions 12
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Related Products 12
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Product
Compatibility 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Related
Publications 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overview of the High Resolution Thermocouple/Millivolt
Input Module 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Objectives 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Module Description 21
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Features
of the Input Module 21. . . . . . . . . . . . . . . . . . . . . . . . . . . .
How Analog Modules Communicate with Programmable Controllers 22
Accuracy 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Getting Started 23
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Summary 23
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installing the High Resolution Thermocouple/Millivolt
Input Module 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Objectives 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Before Y
ou Install Y our Input Module 31. . . . . . . . . . . . . . . . . . . . . .
Electrostatic Damage 31
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Requirements 31
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Module
Location in the I/O Chassis 32. . . . . . . . . . . . . . . . . . . . . . .
Module Keying 32
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Connecting Wiring 33
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Grounding
the Input Modules 34. . . . . . . . . . . . . . . . . . . . . . . . . . .
Installing
the Input Module 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interpreting the Indicator Lights 36
. . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Summary 37
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table of Contents
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Table of Contentsii
Module Programming 41. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Objectives 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Block Transfer Programming 41
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
PLC-2
Applications 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PLC-3 Program Example 42
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PLC-5 Program Example 44
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Module Scan Time 45
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Summary 45
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Module Configuration 51. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Objectives 51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring the Module 51
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input Type 52
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Zoom Feature 52
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature Scale 52
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Real T
ime Sampling 52. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Channel Alarms 53
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Calibration 53
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuration Block for a Block Transfer Write 54
. . . . . . . . . . . . . . .
Bit/Word Descriptions 56
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Summary 58
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Module Status and Input Data 61. . . . . . . . . . . . . . . . . . . . . .
Chapter Objectives 61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reading Data from the Module 61
. . . . . . . . . . . . . . . . . . . . . . . . . .
Bit/Word Descriptions 62
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Summary 63
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Module Calibration 71. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Objective 71. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tools and Equipment 71
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Calibrating your Input Module 71
. . . . . . . . . . . . . . . . . . . . . . . . . . .
About Auto-calibration 71
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Performing Auto-calibration 72
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Performing
Manual Calibration 75. . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Summary 79
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Table of Contents iii
Troubleshooting 81. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Objective 81. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostics Reported by the Module 81
. . . . . . . . . . . . . . . . . . . . . .
Troubleshooting
with the Indicators 82. . . . . . . . . . . . . . . . . . . . . . .
Status Reported by the Module 82
. . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Summary 84
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications A-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Resolution Thermocouple/Millivolt Input Module Accuracy A-2. . .
Lead Resistance Compensation A-3
. . . . . . . . . . . . . . . . . . . . . . . . .
Filtering A-3
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Programming Examples B1. . . . . . . . . . . . . . . . . . . . . . . . . . .
Sample Programs for the Input Module B1. . . . . . . . . . . . . . . . . . . .
PLC-3 Family Processors B1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PLC-5 Family Processors B2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermocouple Restrictions
(Extracted from NBS Monograph 125 (IPTS-68)) C1. . . . .
General C1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Chapter
11
Using This Manual
This manual shows you how to use your High Resolution
Thermocouple/Millivolt 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 individual input module as the “input module” or the ”IXHR”
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
2Overview of the Input Module Description of the module, including general and hardware
features
3Installing the Input Module Module power requirements, keying, chassis location
Wiring of field wiring arm
4Module Programming How to program your programmable controller for this module
Sample programs
5Module Configuration Hardware and software configuration
Module write block format
6Module Status and Input Data Reading data from your module
Module read block format
7Module Calibration How to calibrate your module
8 Troubleshooting Diagnostics reported by the module
Purpose of Manual
Audience
Vocabulary
Manual Organization
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Using This Manual
Chapter 1
12
Chapter Topics CoveredTitle
Appendix A Specifications Your module's specifications
Appendix B Programming Examples
Appendix C Thermocouple Characteristics Extractions from NBS Monograph 125 (IPTS-68)
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.
You can install your input module in any system that uses Allen–Bradley
PLC–3 and PLC–5 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.
These input modules can be used with any 1771 I/O chassis. Communication
between the 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.
Warnings and Cautions
Related Products
Product Compatibility
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Using This Manual
Chapter 1
13
Table 1.A
Compatibility
and Use of Data T able
Catalog
Number
Use of Data T able
Input Output Read Write
Image Image Block Block
Bits Bits Words Words
Compatibility
Addressing Chassis
1/2 -slot 1-slot 2-slot Series
1771-IXHR 8 8 12/13 27/28 Yes Yes Yes A and B
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
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.
For a list of publications with information on Allen–Bradley programmable
controller products, consult our publication index SD499.
Related Publications
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Chapter 2
2
Chapter
21
Overview of the High Resolution
Thermocouple/Millivolt Input Module
This chapter gives you information on:
features of the input module
how an input module communicates with programmable controllers
The High Resolution Thermocouple/Millivolt input module is an intelligent
block transfer module that interfaces analog input signals with any
Allen–Bradley programmable controllers that have block transfer capability.
Note: Use with PLC–2 family programmable controllers is not recommended.
The 1771–IXHR module is only available with 2’s complementary binary as its
only data type. The PLC–2 family does not use 2’s complementary binary.
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 which does not require an 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 is
the same as the total input update time for each analog input module (25ms).
The 1771–IXHR module senses up to 8 differential analog inputs and converts
them to values compatible with Allen–Bradley programmable controllers.
This module’s features include:
8 input channels configurable for thermocouple input ranges or millivolt
input ranges: Types B, E, J, K, T, R and S thermocouples and +100 millivolts
two types of inputs allowed: 4 of one input type and 4 of another
cold junction compensation
scaling to selected temperature range in oC or oF
temperature resolution of 0.1oC or 0.1oF, millivolt resolution to 1 microvolt
user selectable high and low temperature alarms
all features selectable through programming
Chapter Objectives
Module Description
Features of the Input Module
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Overview of the High Resolution
Thermocouple/Millivolt Input Module
Chapter 2
22
self–diagnostics and status reporting at power–up
detection of open circuit if thermocouple fails
automatic offset and gain calibration for each channel
software calibration of all channels, eliminating potentiometers
programmable filters for each group of 4 inputs
X10 magnification (zoom) for millivolt mode
The processor transfers data to and from the module using BTW (block transfer
write) and BTR (block transfer read) 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
Between Processor and Module
Memory
User Program
To Output Devices
PC Processor
(PLC-5/40 Shown)
High Resolution
Thermocouple/Millivolt
Input Module
1771-IXHR
BTW
BTR
5
6
2
3
12933-I
1
4
3. The module converts analog signals into binary format, and stores these
values until the processor requests their transfer.
How Analog Modules
Communicate with
Programmable Controllers
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Overview of the High Resolution
Thermocouple/Millivolt Input Module
Chapter 2
23
4. When instructed by your ladder program, the processor performs a read
block transfer of the values and stores them in a data table.
5. The processor and module determine that the transfer was made without
error, and that input values are within specified range.
6. Your ladder program can use and/or move the data (if valid) before it is
written over by the transfer of new data in a subsequent transfer.
7. Your ladder program should allow write block transfers to the module only
when enabled by the operator at power–up.
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.
User’s Manual
Input Module Field Wiring Arm User's Manual
1771-IXHR Cat. No. 1771-WI
1771-6.5.80
High Resolution
Thermocouple/Millivolt
Input Module
(Cat. No. 1771–IXHR)
10526-I
In this chapter you read about the functional aspects of the input module and
how the module communicates with programmable controllers.
Accuracy
Getting Started
Chapter Summary
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Chapter 3
31
Installing the High Resolution
Thermocouple/Millivolt Input Module
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. Power Requirements
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:
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 char ge 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.
Your module receives its power through the 1771 I/O chassis backplane from
the chassis power supply. The maximum current drawn by the
thermocouple/millivolt input module from this supply is 750mA (3.75 Watts).
Chapter Objectives
Before You Install Your Input
Module
Electrostatic Damage
Power Requirements
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Installing the High Resolution
Thermocouple/Millivolt Input Module
Chapter 3
32
Add this 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 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.
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 modules are 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 these modules 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 20 and 22
Between 24 and 26
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.
Figure 3.1
Keying
Positions
Module Location in the
I/O Chassis
Module Keying
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Installing the High Resolution
Thermocouple/Millivolt Input Module
Chapter 3
33
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
14288
Keying Bands
Upper Connector
CAUTION: The High Resolution Thermocouple/Millivolt Input
Module uses the same keying slots as the 1771–IXE
Thermocouple/Millivolt Input Module. If you are replacing a
1771–IXE with a 1771–IXHR, the ladder program must be modified
to accept the new block transfer format.
Connect your I/O devices to the 1771–WI 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.
Connect inputs in successive order starting with channel 1: positive leads to
even–numbered terminals, negative leads to odd–numbered terminals of the
wiring arm. Make connections to channel 1 at wiring arm terminals 18 (+) and
17(–). Follow the connection label on the side of the module for connecting
the remaining inputs (Figure 3.2).
Connecting Wiring
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Installing the High Resolution
Thermocouple/Millivolt Input Module
Chapter 3
34
Figure 3.2
Connection
Diagram for the 1771-IXHR Inputs
+
+
–
–
1
Do not use
Short circuit
unused pins
Channel 1
Channel 2
18 Input 1 (+ lead)
17 Input 1 (- lead)
16 Input 2 (+ lead)
15 Input 2 (- lead)
14 Input 3 (+ lead)
13 Input 3 (- lead)
12 Input 4 (+ lead)
11Input 4 (- lead)
10 Not Used
9 Not used
8 Input 5 (+ lead)
7 Input 5 (- lead)
6 Input 6 (+ lead)
5 Input 6 (- lead)
4 Input 7 (+ lead)
3 Input 7 (- lead)
2 Input 8 (+ lead)
1 Input 8 (- lead)
Terminal Identification
Terminal Function
Wiring Arm
Cat. No. 1771-WI
Connect positive thermocouple leads
to even-numbered terminals, negative
leads to odd-numbered terminals.
Ground cable shield to I/O chassis mounting bolt.
18
17
16
1
15
14
13
12
11
10
9
8
7
6
5
4
3
2
10527-I
Do not connect an input to terminals 9 and 10. They are reserved for the cold
junction temperature sensor inside the wiring arm. Short circuit unused input
terminals by connecting a jumper wire between the positive and negative input
terminals of each unused channel. Refer to appendix A to determine maximum
cable length.
When using shielded cable or shielded thermocouple extension wire, 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.
Grounding the Input Modules
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Installing the High Resolution
Thermocouple/Millivolt Input Module
Chapter 3
35
Figure 3.3
Cable
Grounding
Ground Shield at
I/O chassis
mounting bolt
Shield and drain
twisted into
single strand
Field Wiring Arm
17798
Refer to Wiring and Grounding Guidelines, publication 1770-4.1 for additional information.
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Installing the High Resolution
Thermocouple/Millivolt Input Module
Chapter 3
36
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.
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.
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
RUN
FLT
TC/MV
Module
10528-I
Installing the Input Module
Interpreting the Indicator
Lights
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Installing the High Resolution
Thermocouple/Millivolt Input Module
Chapter 3
37
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.
Chapter Summary
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Chapter
41
Module Programming
In this chapter, we describe
Block Transfer programming
Sample programs in the 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. Refer to chapter 5 to see the 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,
alarms, etc.) and block transfer read activity.
The following example programs illustrate the minimum programming required
for communication to take place.
Due to the number of digits required for high resolution readings, the
1771–IXHR module only reads input values in 2’s complement binary. Since
the PLC–2 family PLCs do not naturally read this data format, the IXHR
module is not recommended for use with PLC–2 family programmable
controllers.
Chapter Objectives
Block Transfer Programming
PLC-2 Applications
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