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The following actions are taken when a link has timed out.
1.Link Timeout fault is logged in the PLC Fault Table.
2.The OK and Local LEDs on the Redundancy Communications Module in the RCM to BTM link that failed continue to be maintained (that is, they will stay ON and the Local LEDs reflect the state of the Local unit) but the Remote LEDS are turned OFF. The LEDs on the other RCM continue to be updated as long as that RCM is OK.
3.The module fault contact is set. If the failed link is through the Redundancy Communications Module in the local main rack, then the SLOT_0X fault contact is set (X is the slot number for the Redundancy Communications Module). If the failed link is through the Redundancy Communications Module in the other unit's main rack, then the SLOT_71 fault contact is set.
4.The corresponding communications link is no longer used. If the other link is still operating, then that link will be used for all further data transfer and units can remain in synchronization.
5.If no other communications link is available, then the unit functions as a
A power cycle or storing a hardware configuration to either unit is required to restore the link to service. In this case, if the RCM is at fault, it will need to be replaced before power is restored.
Fault Actions in a CPU Redundancy System
Fault actions in the Hot Standby CPU Redundancy System are handled differently than fault actions in a
When the two CPUs are synchronized the following faults are considered FATAL and will cause the affected unit to transition to STOP/FAULT mode.
Tany fault that degrades performance
any fault that causes loss of control of I/O
The configurable fault actions are applied whenever the system is running in
Note
In a CPU redundancy system a Fatal fault from a Genius Bus Controller causes the active unit to transition to STOP/FAULT mode. All Diagnostic faults allow the CPU to continue to operate.
Chapter 5 Fault Detection |
