Rockwell Automation 1785-CHBM ControlNet PLC-5 Hot Backup System User Manual - Manual (Page 84)

Publication 1785-UM024B-EN-P - January 2003
B-4 Backup States
If there is a valid partner PLC-5 ControlNet backup system, and the
systems are connected on the ControlNet channel, the Qualified LED
is solid yellow. This indicates that the necessary configuration needed
to allow the backup pair to successfully communicate with each other
has been achieved.
You can make any configuration changes you wish to the ControlNet
Backup Configuration and Status file while the PLC-5 processor is in
the No Control backup state. Note that placing an invalid parameter
into the ControlNet Backup Configuration and Status file causes the
processor to switch to the Invalid backup state.
Primary Backup State
When a PLC-5 ControlNet backup system is in Run mode, and is
actively controlling all of the system outputs, it is in the Primary
backup state. The Primary LED is green, either blinking or solid; the
Secondary LED is off. The PLC-5 processor can go out of Primary
backup state if either the PLC-5 system is switched out of Run mode
or the partner PLC-5 becomes the Primary.
If there is a valid partner PLC-5 ControlNet backup system, and the
systems are connected on the ControlNet channel, the Qualified LED
is on. If the Qualified LED is solid yellow, the partner PLC-5 is not a
qualified secondary system, however the two systems are properly
configured to communicate with each other. If the Qualified LED is
solid green, the partner PLC-5 is a qualified secondary and could take
control of the system outputs if necessary. If the Qualified LED is off,
then there is no partner PLC-5 system communicating with this PLC-5
system on the ControlNet channel.
When the PLC-5 is in the Primary backup state, you can no longer
force the backup system to be in the Invalid backup state through
configuration changes. All configuration changes are checked for
validity before being accepted.
TIP
If a newly-entered configuration parameter is invalid,
the backup system uses the previous configuration
values.