Rockwell Automation 1785-CHBM ControlNet PLC-5 Hot Backup System User Manual - Manual (Page 128)

Publication 1785-UM024B-EN-P - January 2003
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Note: When performing editing on either PLC-5, we
recommend that you disable this feature first. This will avoid a
situation where the secondary PLC-5 cannot be qualified
because there are memory section differences between it and
the primary.
F
forced switchover A configuration option that allows you to on demand, force
transfer of control from the primary PLC-5 to the secondary and
vice versa.
I
invalid backup state When an improper backup configuration exists, the PLC-5
ControlNet backup system goes into the invalid backup state.
Both the Primary and Secondary LEDs on the 1785-CHBM
cartridge are solid red when the system is in this state, and the
Qualified and Synchronous LEDs are off.
L
lonely primary backup state When there are no valid scheduled connections on the
ControlNet channel and the primary PLC-5 is not controlling the
system outputs on the ControlNet channel, the ControlNet
backup system goes into the lonely primary backup state.
M
maximum program scan time A parameter you configure that is applicable only in
Synchronous mode. The allowable values are between 1 and
127 Network Update Times (NUTs) in milliseconds. The
maximum program scan time is used internally to create the
adjusted maximum program scan time, which is the constant
time value for synchronous program scans.
You can configure the Maximum Program Scan time value via
the RSLogix 5 Backup Configuration dialog. You can modify this
value at any time, including when the ControlNet hot backup
system is operating in Run mode, by changing the configuration
value in the primary PLC-5. The secondary PLC-5 always
assumes the configuration setting in the primary.