A communication/PLC failure occurs where the enabler can no longer communicate over any network path to a running healthy PLC; for example network down, PLC powered down, PLC stopped or Health bit clear.
Master PLC - the
enabler updates the diagnostic points then performs a failover to
the next highest ranking running Healthy PLC with the Health and
master mode bits set.
Standby PLC - the
enabler updates the diagnostic points for the PLC.
The enabler then retries communications to the failed PLC at the configured heartbeat rate.
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Series 90 TCP/IP Redundancy failure conditions and actions. |
