Rockwell Automation 1785-CHBM ControlNet PLC-5 Hot Backup System User Manual - Manual (Page 53)

Publication 1785-UM024B-EN-P - January 2003
Installing and Configuring Your ControlNet PLC-5 Backup System 3-27
Downloading Editing Changes
Downloading a program saved from one processor to another can
greatly simplify the transfer of editing changes from one processor to
another. If you follow the steps described earlier in this chapter, in the
section entitled “Create and Download the Project for the Second PLC
Processor,” then you can complete this processor-to-processor
download. The steps outlined there ensure that a new, different
project name is created for the program that is downloaded. They also
ensure that the ControlNet configuration information remains unique
for each of the processors, which must be the case.
This means that any edits you make to the I/O map table, you must
manually make on each processor.
Testing Data Table Edits
There may be instances where edits are made to the data table
structure, and these edits need to be tested on a running system.
If this is the case, place one of the processors in your backup system
into Program mode, and make the edits to that processor. Make sure
that the data table structure and the ladder program equivalence
checks are disabled while performing edit switchovers. Ladder
program equivalence checks are dependent on data table structures so
ladder program equivalence checking must also be disabled.
Next, place the edited system into Run mode. A forced switchover can
be performed, which makes the edited processor the primary, and the
unedited processor the secondary. If problems occur within the edited
system, a second forced switchover makes the unedited processor
primary again.
Note: Qualification crossloading and on-demand crossloading are
disabled when the data table structures between the processors are
different.