User Manual

Alarm management
Alarm response of the function blocks
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In the case of the binary output, [Rlb] errors may originate both from the
[PrVal] (or associated physical output) and from the [FbVal] (or associated
physical input).
● A FAULT alarm will disappear as soon as the variable [Rlb] changes from a
value not equal to NO_FAULT_DETECTED back to the value
NO_FAULT_DETECTED.
An OFFNORMAL alarm is generated:
● A monitored, referenced object is not enabled
● A referenced object cannot be enabled
A FAULT alarm is generated when:
● A referenced object is not found
● A referenced object is not a commandable object (output object or value
object)
● Invalid priorities are used for the referenced object (valid priorities are
Priority 2, 5, 14 and 16)
● ProgramValue or ExceptionValue are outside the permissible range
● The referenced objects have a different number of operating modes
● The function table is empty
Discipline I/Os and Group
Alarm handling is identical for Discipline I/O and Group blocks. These function
blocks only support FAULT alarms.
● A FAULT alarm is generated as soon as the [Rlb] property of the function
block assumes any value other than NO_FAULT_DETECTED. In particular,
this is the case when [Rlb] changes from a value not equal to
NO_FAULT_DETECTED to another value not equal to
NO_FAULT_DETECTED.
● A FAULT alarm will disappear as soon as the [Rlb] property of the function
block changes from a value not equal to NO_FAULT_DETECTED back to the
value NO_FAULT_DETECTED.
The following conditions cause a FAULT alarm to be initiated:
● Address conflict:
The subsystem fails to recognize the device defined in the [IOAddress]
parameter. This alarm is issued by the associated function block.
● Communications error:
The subsystem indicates a communications failure. This can be due to a
bus open circuit or a faulty device, or, very rarely, to a communications
overload on the bus. These alarms are indicated by the shared function
block.
Command Control
Alarm response