Rockwell Automation 1785 PLC-5 User Manual download pdf (Page 85)

Operating Your PLC-5 Backup System

Chapter 5

5-21

To avoid a control switch from the primary to the secondary processor when

you attempt to edit the ladder program or data table of the primary PLC-5

processor using a programming device:

1. Do not switch the primary PLC-5 processor to REMOTE PROGRAM

mode. Switch the primary PLC-5 processor to REMOTE RUN mode.

Important: If you switch the primary processor to REMOTE PROGRAM

mode, the processor transfers control to the secondary processor. In most

cases, the new primary then switches to Remote Program mode, shutting the

system down.

2. Make edits in the secondary processor first. However, make sure that all

necessary changes are made in both processors.

Important: Using the on-line editing/programming function can cause the

primary and secondary systems to diverge if the system should switch before

you complete the edits in both processors.

This chapter described the basic operation of the 1785-BCM modules and the

PLC-5 backup system, and gave you procedures for operating your module.

Read the next chapter to learn how the backup system operates at switchover,

and how you need to account for this when programming your system.

Editing or Programming

On-line

What to Do Next

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Rockwell Automation 1785 PLC-5 User Manual Page 85