A-BPLC-5 Backup Communication Module

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.

ATTENTION: Identifies information about practices or

circumstances that can lead to personal injury or death, property

damage or economic loss.

Attention helps you:

- Identify a hazard

- Avoid the hazard

- recognize the consequences

Important: Identifies information that is critical for successful application and

understanding of the product.

I

Summary of Changes

This release of the publication contains new updated information.

To help you find updated information in this release of the manual, we

have included change bars as shown to the left of this paragraph.

Using This Manual

This manual shows you how to use 1785-BCM series B backup communication

modules with a PLC-5 programmable controller (PLC-5/15 series B, -5/20,

-5/25, -5/30, -5/40, and -5/60 processors). These modules enable high-speed

communication transfer between two PLC-5 processors and provide system

backup should the processor or other equipment in the system fail.

In this manual we describe:

 backup system concepts

 procedures for installing and operating your modules

 various programming techniques

Before you read this manual or attempt to use 1785-BCM modules, you should

be familiar with PLC-5 programmable controllers. In addition, you need to be

familiar with:

 6200 Series Software

 remote I/O system

 Data Highway Plus network

 block-transfer instructions

The following table lists each chapter of this manual and describes the contents

of each.

If you want to read about: Refer to chapter:

an overview of backup concepts; description of backup

system that uses 1785-BCM module.

1 – Backup Concepts for the PLC-5 System

a description of 1785-BCM module hardware. 2 – Understanding the 1785-BCM Module Hardware Components

procedures for installing the1785-BCM module; procedures

for connecting the backup system.

3 – Installing Your 1785-BCM Series B Backup System

description of 1785-BEM backup expansion module and

procedures for installing

4 – Installing Your 1785-BEM Module

an overview of how the 1785-BCM module and the backup

system operate; procedures for starting, powering-up,

disconnecting, and restarting a repaired system.

5 – Operating Your PLC-5 Backup System

considerations for timing, divergence, I/O forces, Data

Highway Plus switching, Remote I/O switching, special

sections of the data table, and data integrity.

6 – Switchover Considerations

If you want to read about: Refer to chapter:

two methods you can use to program your backup system;

considerations for using instructions that can cause

problems in your backup system.

7 – Programming Techniques

1785-BCM module faults (as indicated by the module’s

status indicators and bits of the system status word) and

procedures for correcting faults.

8 – Diagnosing Faults

specifications for the 1785-BCM module. 9 – Specifications

sample Programs for method 1 (transferring one block of

data at a time) and method 2 ( transferring multiple blocks

of data at a time); data table transfer times for both

programming methods.

Appendix A – Sample Programs

answers to common PLC-5 backup system questions;

delay times between the primary and the secondary

processor for both programming methods and formulas for

determining delay times.

Appendix B – Reference Information

describes differences between a 1785-BCM series A

backup module and a 1785-BCM series B backup module

Appendix C – Using a Series A 1785-BCM Module

PLC-5 Processor Reference

In this manual, the term PLC-5 processor refers to the following processors:

 PLC-5/11

 PLC-5/15

 PLC-5/20

 PLC-5/25

 PLC-5/30

 PLC-5/40

 PLC-5/60

 PLC-5/80

Contact your Allen-Bradley Sales Office or your Allen-Bradley distributor for

additional PLC-5 processors that can be configured with the 1785-BCM

modules.

Some terms used in this manual may be unfamiliar to you. We list these terms

with a brief definition of each.

HSSL is the 1785-BCM module’s High-Speed Serial Link. It is a dedicated

communication link between the primary and secondary 1785-BCM modules