Rockwell Automation 1785-CHBM ControlNet PLC-5 Hot Backup System User Manual - Manual (Page 17)

Publication 1785-UM024B-EN-P - January 2003
Backup Concepts for the ControlNet PLC-5 Backup System 1-3
Qualification
When bringing the secondary programmable controller of a backup
system online, it is important to ensure that it is in a state that will
enable it to take over the control of the system in the event of a
primary failure. This process of verifying and conditioning the state of
the secondary programmable controller is known as qualification.
Switchover will not occur without a qualified secondary
programmable controller. Additionally, the system is not truly
considered a backup system until the secondary programmable
controller has successfully completed qualification.
The qualification phase includes several tests and verifications
between the primary and secondary programmable controllers, as
well as data table file crossloading. You can tailor these tests,
verifications, and data table file crossloads to ensure the level of
system integrity required for your application. These tests and
verifications may cover:
• configuration file validity and integrity checking
• application program and data file structure equivalence
checking
• I/O map connection comparison
• force table comparison
• status file comparison
Data table file crossloading from the primary to the secondary
programmable controller may include the transfer of integer values,
floating point values, timers, counters, PID values, and others you
select.