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For alarms (alarms, warnings, information) of the TCD the TCDHelpOffNormalAlarmType as defined in Table 21 shall be used, if the alarm facet is supported. A machine which connects to a TCD via OPC 40082-1 shall subscribe this event.

Table 21 – TCDHelpOffNormalAlarmType Definition

Attribute Value        
BrowseName TCDHelpOffNormalAlarmType        
IsAbstract False        
References Node Class BrowseName DataType TypeDefinition Other
Subtype of 3:HelpOffNormalAlarmType (defined in OPC 40083)          
0:HasProperty Variable DeviceMappingNumber 0:UInt32 0:PropertyType M, RO

The value of DeviceMappingNumber corresponds to the value given in the instance of the OperationType (see 9.1) for assigning the alarm to a device.

For unique identification of the alarm event, the SourceNode (included in BaseEventType) of the device needs to be sent for every alarm message. The SourceNode includes the namespace number and the Identifier from the object instance of TCD_InterfaceType (for general events) or the NodeId of a child element (e.g. a variable of MonitoredParameterType if this is out of tolerance).

For the Severity Property (included in BaseEventType) the following classes shall be used:

Table 22 – Severity Classes

Range of Severity Description
667-1000 Messages of high urgency (error, system alarm): Limit values have been exceeded. The transgression has a direct influence on the operational safety of the unit.
Acknowledgement: compulsory
334-666 Messages of medium urgency (warning, process alarm):
Limit values have been exceeded. The transgression has no influence on the operational safety of the unit.
Acknowledgement: not compulsory
1-333 Messages of low urgency (Information)

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