A communication/PLC recovery occurs where the enabler re-establishes communication over a network path to a running healthy PLC; for example network recovered, PLC powered up or Health bit becomes set.
The action taken by the enabler depends on the ranking of the PLC.
Higher Ranking PLC - the enabler checks the Health and Master bits. It updates the diagnostic points for the PLC. If both mode bits are set, the enabler selects this PLC as the current master.
Lower Ranking PLC - the enabler checks the Health and Master bits and, updates the diagnostic points for the PLC.
Series 90 TCP/IP Redundancy failure conditions and actions.