Rockwell Automation 1785-CHBM ControlNet PLC-5 Hot Backup System User Manual - Manual (Page 130)

Publication 1785-UM024B-EN-P - January 2003
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Q
qualification A phase of operation each PLC-5 goes through before being
considered ready, or qualified, to take control of the system
outputs. The qualification phase begins when the PLC-5 is
switched into Run mode. During qualification, various checks
are made to ensure that the PLC-5 is properly configured.
If the secondary PLC-5 is the one going through qualification,
various data is read from the primary. If all required checks and
transactions are completed successfully, the PLC-5 will be
qualified to take over control from the primary system, should
conditions warrant.
R
requalification of dual primaries A configuration option that allows you to requalify a hot backup
PLC-5 if dual primary PLC-5s exist. Increases the availability of a
qualified backup system if communication is broken between
the two PLC-5s.
Run mode For a standalone PC, this is the mode of operation where the
program scan is being executed and outputs are actively being
controlled.
S
secondary PLC-5 The PLC-5 in the hot backup system that is actively backing up
the primary PLC-5. This PLC-5 is not in control of the system
outputs at the present time. A second PLC-5 does not truly
become a secondary until it is switched into Run mode and
successfully completes qualification.
secondary qualification time delay A parameter you configure that specifies the amount of time a
secondary PLC-5 will execute in Run mode before becoming
qualified. This delay time is in addition to the time required for
the secondary to successfully complete all other requirements
and transactions necessary to become a qualified secondary.
You can configure this parameter by writing into word 13 of the
backup configuration and status file. You can modify it at any
time, however it is only applicable while a secondary is
becoming qualified. If the configured value on the primary and
secondary is different, the secondary will assume the value on
the primary. The allowable times are 0 to 65,535 milliseconds,
with the default set to 0.