Server status and OPC watchdog points

To enable the interface to track the availability of OPC servers, use PI ICU to configure watchdog PI points that are mapped to OPC items that reliably reflect the state of the OPC server.

The OPC items must contain a positive integer if the OPC server is running or 0 if the OPC server is unavailable, and OPC watchdog points must have an integer data type.

When choosing the OPC items that you map to the OPC watchdog points, consider which ones are most reliable and representative of the state of the OPC server. For example, in a manufacturing context, an item that counts number of units manufactured might make sense. To ensure that the primary and backup OPC servers report status consistently, choose an OPC item based on the data source itself (as opposed to an item that originates in the OPC server).

To ensure that the values in OPC watchdog points are valid (0 or positive integer), use scaling and transformation for PI points as required.

To reduce system workload, configure the OPC watchdog points as advise points if the OPC server supports advise points. If not, assign them to a scan class with a short scan period.

If more than one instance of the interface is running, either on the same or different nodes, you must create separate OPC watchdog points for each instance of the interface. When the instance ID is not used, each instance scans only those PI points with pointsource attributes that matches the interface instance ps parameter. When the instance ID is used, the pointsource attribute must match the interface ps parameter and the location1 attribute must match the interface id parameter.