User Manual

Alarm management
Alarm response of the function blocks
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CM110664en_07 147 | 353
The subsystem indicates an inadmissible response from a device e.g. in the
case of faulty QAX… room unit. These alarms are indicated by the shared
function block.
Multistate Input and Multistate Value
The alarm handling process is identical for the function blocks Multistate Input
and Multistate Value.
● An OFFNORMAL alarm occurs when [PrVal] assumes one of the values
specified under [RefVals] (list of multistate values) and remains at this
value for a period at least equivalent to the time specified by the variable
[TiMonDvn]. In particular, this applies when [PrVal] changes from one value
in [RefVals] to another value in [RefVals].
● An existing OFFNORMAL alarm condition will disappear either if [PrVal]
reverts to a value not contained in the [RefVals] list, and retains this value
for a period at least equivalent to the period specified in [TiMonDvn], or if
[EnAlm] is changed from TRUE to FALSE (see further below).
● A FAULT alarm is generated when 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.
Multistate output
The alarm handling procedure for the Multistate Output function block is
different from the alarm handling procedure for the Multistate Input and
Multistate Value function blocks, but follows the same principles as for the
Binary Output block:
● An OFFNORMAL alarm occurs when the current values of the variables
[RwVal] and [FbVal] differ from each other for a time period at least
equivalent to the delay time specified in [TiMonDvn].
● An existing OFFNORMAL alarm will disappear when the current [PrVal] und
[FbVal] are again identical and remain so for a period at least equivalent to
the time specified in the variable [TiMonDvn].
● A FAULT alarm is generated when the [Rlb] property of the function block
assumes any value other than NO_FAULT_DETECTED. In particular, this is
the case when the [Rlb] property changes from a value not equal to
NO_FAULT_DETECTED to another value not equal to
NO_FAULT_DETECTED. In the case of the multistate output block, [Rlb]
errors may originate both from the [PrVal] (or associated physical output)
and from [FbVal] (or associated physical input).
● A FAULT alarm will disappear as soon as [Rlb] changes from a value not
equal to NO_FAULT_DETECTED back to the value NO_FAULT_DETECTED.