139
 Alarm Processing 
AO Function Block
Alarm Processing
When a condition shown inTable 40 is met, the AO block changes the bit statuses of 
BLOCK_ERROR accordingly and generates a block alarm.
Table 40 BLOCK_ERROR in AO Block
Bit Name of Error
Represented
Condition
3 Simulate Active SIMULATE is active.
4 Local Override Fault state is on, and Propagate Fault Backward is false.
7
Input Failure / process 
variable has BAD status
Propagate Fault Backward in STATUS_OPTS is false, and the 
sub-status component of the status of READBACK is sensor 
failure or device failure.
15 Out-of-Service The target mode is O/S.