The enabler responds to fault condition as follows.
Failure conditions and actions using Triplex enabler include the following.
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Server failure. |
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Server recovery. |
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Communication path failure detected by the slave enabler. |
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Communication path recovery detected by the slave enabler. |
Server Failure
A Server failure occurs when the Secondary Server can no longer communicate to the Primary Server; for example; the project on Primary Server stopped.
The enabler on the slave node becomes the active master and begins collecting data from the highest ranking running Healthy PLC with the Health and master mode bits set.
The enabler updates the diagnostic points to reflect the status of connections on the new active master node. .
Server Recovery
A Server recovery occurs when the Configured Primary server becomes active and a transition takes place. .
The enabler on the new slave node suspends polling the devices, and returns to heartbeat processing.
The enabler on the recovered node becomes the active master and begins collecting data from the highest ranking running Healthy PLC with the Health and master mode bits set.
Communication Path Failure detected by the Slave Enabler
A communication path failure occurs when the enabler on the Secondary Server can no longer communicate over a configured communication path to a PLC. .
The enabler generates a $DEVICE alarm to indicate the communication path in error. After all paths to the device are tested, a "summary" alarm is generated, if necessary. The text of the alarm message contains an error code, which is an integer that indicates the connection status of each path. If you turn the error code into a bit string, the bits can be interpreted as follows:
bit 0: primary PLC primary cable
bit 1: primary PLC secondary cable
bit 2: secondary PLC primary cable
bit 3: secondary PLC secondary cable
bit 4: third PLC primary cable
bit 5: third PLC secondary cable
If the bit is equal to 1, then the enabler cannot communicate over that path. As an example, if both cables to the Primary PLC are disconnected, but all other paths are operational, bits 0 and 1 would equal 1, so the error code would equal 3 (000011 = 3).
Communication Path Recovery detected by the Slave Enabler
A communication path recovery occurs where the enabler re-establishes communication over a network path to a PLC..
If all communication paths are now operational to the device, a $DEVICE alarm is generated to indicate full recovery. If a different communication path still is in error, a $DEVICE alarm is generated as described above.
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Other Series 90 TCP/IP Triplex topics. |
