Rockwell Automation 1785-CHBM ControlNet PLC-5 Hot Backup System User Manual - Manual (Page 105)

Publication 1785-UM024B-EN-P - January 2003
Data Table Crossloading C-7
Qualification Data Table Crossload
The Qualification data table crossload occurs when a processor in the
No Control state transitions from Program mode to Run mode, and the
other processor is the primary processor. This complete data table
crossload is performed while the qualifying PLC-5 system is still in
Program mode. It is necessary to remain in Program mode until the
complete data table crossload is finished in order to prevent the
qualifying system from major faulting or going off into an odd state
due to uninitialized data table values.
All elements of all data table files are crossloaded in the Qualification
data table crossload with the exception of the following files. These
files cannot be crossloaded because they contain processor-specific
configuration and status information.
• System Status File (S2)
• ControlNet Backup Integer File
• ControlNet Configuration File
• ControlNet I/O Status File
• ControlNet Diagnostic File
• ControlNet Data Output File (DOF)
• ControlNet Data Input File (DIF)
Although the System Status File is not crossloaded, the real time clock
(6 words) in the System Status File is crossloaded from the primary
processor to the partner processor.
Qualification State Data Table Crossload
Even though a Qualification data table crossload has occurred during
qualification, some of the crossloaded data may have become stale.
This is because the Qualification data table crossload occurs while the
processor is in Program mode. For example, if the Qualification data
table crossload takes 10 seconds, the data in the original data table file
that was transferred is 10 seconds old. In order to bring certain state
information in the data table up to date, a Qualification State data
table crossload is performed.
The Qualification State data table crossload occurs when the
qualifying processor has transitioned into Run mode, but before the
qualifying processor has become qualified.