OPC Studio User's Guide and Reference
Alarms - Shelving and Unshelving
In order to set the alarm condition to the Unshelved state, use the IEasyUAAlarmsAndConditionsClient.Unshelve extension method.
In order to set the alarm condition to the TimedShelved state, use the IEasyUAAlarmsAndConditionsClient.TimedShelve extension method.
In order to set the alarm condition to the OneShotShelved state, use the IEasyUAAlarmsAndConditionsClient.OneShotShelve method.