Configure a single watchdog PI point

If you can determine the availability of the OPC server based on a single OPC item, create a single watchdog PI point. When the value of the OPC item is 0, PI Interface for OPC DA attempts to connect to the other server. If it cannot connect successfully to the other server within the specified connection timeout period, it attempts to reconnect to the first OPC server again.

To create and configure an OPC watchdog point:

1. Create a PI point. Map the point to an OPC item that you consider a reliable indicator of server status.

   The OPC item to which the point is mapped must be defined identically in both the primary and backup OPC servers, while possibly having different values on the two servers.

2. Indicate the watchdog point for the primary and backup OPC servers: Using PI ICU, go to the OPCInt > Failover > Server Level page and configure the Primary Server Watchdog Tag and Backup Server Watchdog Tag fields.

3. Verify that the OPC item triggers failover:

   1. Start the OPC servers and verify that the watchdog item is non-zero on at least one of the servers. Start the interface.

   2. Manually set the OPC item to 0 on the currently-connected server.

   3. Examine the AF SDK log or check the Active Server point to determine whether the interface failed over to the other OPC server.