GE GFK-0787B Manuel D’Utilisation
3
3-10
Genius
tModular Redundancy Flexible Triple Modular Redundant (TMR) System
User’s Manual – March 1995
GFK-0787B
Hot Standby Mode
Individual blocks can be included in the output subsystem as GMR blocks, Hot Standby
blocks, or non-GMR blocks. There are significant differences in block operation between
these three operating modes.
blocks, or non-GMR blocks. There are significant differences in block operation between
these three operating modes.
Operation of GMR output blocks and non-GMR blocks is explained elsewhere in this
chapter. Hot Standby mode is a type of Genius redundancy that can be used with or
without GMR.
chapter. Hot Standby mode is a type of Genius redundancy that can be used with or
without GMR.
Basic Hot Standby Mode Operation
In basic Hot Standby mode (without GMR), blocks receive outputs from two PLCs, but
they are normally controlled directly by the PLC at serial bus address 31. If no output
data is available from bus address 31 for a period of three bus scans, the outputs are
immediately controlled by the PLC at bus address 30. If output data is not available
from either 30 or 31, outputs go to their configured default or hold their last state. The
PLC at bus address 31 always has priority, so that when 31 is online, it always has control
of the outputs.
they are normally controlled directly by the PLC at serial bus address 31. If no output
data is available from bus address 31 for a period of three bus scans, the outputs are
immediately controlled by the PLC at bus address 30. If output data is not available
from either 30 or 31, outputs go to their configured default or hold their last state. The
PLC at bus address 31 always has priority, so that when 31 is online, it always has control
of the outputs.
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Bus Controller
31
Bus Controller
30
outputs
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Selection of Hot Standby mode is made during block configuration.
Hot Standby Mode in a GMR System
If a block is set up for Hot Standby mode in the GMR configuration, its Hot Standby
operation is automatically expanded to include three PLCs: 31, 30, and 29.
operation is automatically expanded to include three PLCs: 31, 30, and 29.
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PLC 31
PLC 30
outputs
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PLC 29
The manner of operation is the same. The block uses outputs from PLC 31 if they are
available. If not, it uses outputs from PLC 30. If outputs from both PLC 31 and PLC 30
are not available, the block uses outputs from PLC 29. If output data is not available
from any of the three PLCs, outputs go to their configured default or hold their last state.
The PLC at bus address 31 always has priority, so that when 31 is on–line, it always has
control of the outputs.
available. If not, it uses outputs from PLC 30. If outputs from both PLC 31 and PLC 30
are not available, the block uses outputs from PLC 29. If output data is not available
from any of the three PLCs, outputs go to their configured default or hold their last state.
The PLC at bus address 31 always has priority, so that when 31 is on–line, it always has
control of the outputs.
As mentioned, this assignment of an additional Hot Standby PLC happens automatically
for a Hot Standby block that is included in the GMR configuration.
for a Hot Standby block that is included in the GMR configuration.