Rockwell Automation 1785-BCM_BEM, D17856.5.4 PLC-5 Backup Communication Module User Manual - Manual (Page 5)

Preface
ii
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
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
and is used to pass I/O, status, and data table information.
Primary System is the PLC-5 processor that controls the I/O and the other
equipment associated with that processor.
Secondary System is the PLC-5 processor that is ready to assume control of
the I/O and the equipment associated with that processor.
Backup System is the primary and secondary systems.
PLC-5 Processor Reference
Terms and Conventions