To provide asset specific information on failure or maintenance conditions the alarming mechanism of OPC UA is used. The 2:IDeviceHealthType already defines the optional 2:DeviceHealthAlarms folder, where such alarm Objects can be provided. However, it is not required to provide the folder and the alarm Objects in the AddressSpace. Servers should use the AlarmTypes defined in OPC 10000-100 (2:DeviceHealthDiagnosticsAlarmType and subtypes) to expose the asset specific information. The event fields shall be used as defined in OPC 10000-5 and OPC 10000-9. The 0:SourceNode and 0:SourceName shall identify the asset. The 0:Severity should be used as defined in Table 15. Applications may refine those categories to a more detailed categorisation.
Table 15 – Usage of Severity for Alarms containing asset specific information
|
Severity |
Classification |
Description |
|
801-1000 |
Critical Fault |
The asset has permanently failed. |
|
601-800 |
Major Recoverable Fault |
The asset can no longer perform its function. Intervention is required. |
|
401-600 |
Minor Recoverable Fault |
The asset has experienced a problem but is able to continue operation until intervention occurs. |
|
301-400 |
Maintenance Needed |
Service is required to keep the asset operating within its designed tolerances. |
|
201-300 |
Limited Resource Capacity Near Limit |
A limited resource met a threshold beyond which a more serious fault would occur. |
|
1-200 |
- |
Used when the alarm is not active. |