State Industries FANUC GFK-0827 - Manual (Page 94)

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83 GFK-0827 Chapter 4 Operation
Genius Bus
Genius bus faults are not fatal to the PLC. However, if a bus fault exists, it exists for both
systems. There may be situations where one controller can communicate to more blocks
than the other controller can. Since both controllers are running with the same outputs
and shared inputs, and both controllers are still synchronized, the blocks will choose
which controller to respond to, if either can be heard.
The Genius bus can be repaired without disturbing power to either system and thus
without disturbing which PLC is in control of the process. Replacement of a bus can be
done on line but is not recommended because all devices on that bus will be lost until
the bus is repaired.
Genius Blocks
The failure of a single block is not fatal to the PLC.