Automatic Role Switch - Emerson PACSystems RX3i Application Manual

Application Guide
GFK-2928C
Note:
TO_B
Outputs
OK
BSY
FLT
ST_LO
ST_HI

Automatic Role Switch

Zoom into the DBUS block to display the Automatic Role Switch (AUT_SW) function block.
This function block allows the user to transfer control from the current Active PLC to the
current Backup PLC in the event that a GCG associated with the Active PLC fails.
While the function block is enabled, it will evaluate the Genius combined status bits that are
received from the Active PLC and compare them with the Genius combined status bits in
the Backup PLC. The comparison is performed within the Serial Bus Address range of 01.29.
If any bit in the Backup PLC is ON while it's comparable bit in the Active PLC is OFF, a
corresponding timer will be enabled. If the timer expires, a service request will be issued to
perform a role switch.
PLC Hardware Configuration
connected onto Bus A. This reference may be turned on by selecting
the contact and then right click. The reference maintains its state.
The function will turn ON its fault output if TO_A and TO_B are both ON or both OFF.
This is like TO_A, except that it applies to switching a device to Bus
B.
The function executed successfully.
The function is busy executing a communication request that has
been issued to the associated PROFINET Controller module.
Typically, this will be related to the current Bus Switch event.
The bus switching request was not completed due to an error in the
COMMREQ structure, a fault related to the GCG/PNC/Genius device,
or a timeout because a component is not available.
The value of the low-order word of the COMMREQ. Refer to the GCG
User Manual to interpret the result.
The value of the high-order word of the COMMREQ. Refer to the GCG
User Manual to interpret the result.
Chapter 5
Oct 2019
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