OPC Client.NET Runtime

There are multiple Parameter types for each Tag.  Of each of these you will also see Time On and Count items if that feature is enabled for the specific parameter.

Following are the most commonly used parameters.

Value is the actual value of the Tag and can have Read and Write access if the Tag Source is set to Value or OPC Item.  Read only if the Source is set to Calculation or remote Tag.  The data type depends on the Tag’s Data Type.

HighHighAlarmLimit is the High High Alarm Limit of the Tag and can have Read and Write access if the Tag Source is set to Value or OPC Item.  Read only if the Source is set to Calculation or remote Tag.  The data type is a Double or VT_R8.

HighAlarmLimit is the High Alarm Limit of the Tag and can have Read and Write access if the Tag Source is set to Value or OPC Item.  Read only if the Source is set to Calculation or remote Tag.  The data type is a Double or VT_R8.

LowAlarmLimit is the Low Alarm Limit of the Tag and can have Read and Write access if the Tag Source is set to Value or OPC Item.  Read only if the Source is set to Calculation or remote Tag.  The data type is a Double or VT_R8.

LowLowAlarmLimit is the Low Low Alarm Limit of the Tag and can have Read and Write access if the Tag Source is set to Value or OPC Item.  Read only if the Source is set to Calculation or remote Tag.  The data type is a Double or VT_R8.

DigitalAlarmLimit is the Digital Alarm Limit of the Tag and can have Read and Write access if the Tag Source is set to Value or OPC Item.  Read only if the Source is set to Calculation or remote Tag.  The data type is a Boolean or VT_BOOL.

AlarmStatusHighHigh is a read only Boolean indicating the current state of the Tag’s High High alarm condition.

AlarmStatusHigh is a read only Boolean indicating the current state of the Tag’s High alarm condition.

AlarmStatusLow is a read only Boolean indicating the current state of the Tag’s Low alarm condition.

AlarmStatusLowLow is a read only Boolean indicating the current state of the Tag’s Low Low alarm condition.

AlarmStatusDigital is a read only Boolean indicating the current state of the Tag’s Digital alarm condition.