Specify the connection priority for PI SDK clients

Use PI Connection Manager to specify default connection preferences, which determine the order that PI SDK connects to servers in a Data Archive collective. You specify this preference with a connection priority value. PI SDK attempts to connect to servers in the order specified by the priority. Beginning with PI Server 2018, when collective members have the same priority value, connections to those servers are established randomly. By default, all Data Archive collective members are assigned a priority value of 1.

You can set different priority values at different workstations to distribute work among the servers in a collective. Give the server with the highest priority a value of 1 and other servers incremental values (2, 3, 4, and so on). Set the priority to -1 to prevent connections to a server. For example, you can force workstations to connect to only local servers by setting the priority value to -1 for remote servers.

Beginning with PI Server 2018, the connection priority you define accommodates failback situations when a client is using PI AF SDK 2018 or later. In earlier releases, when a higher priority server went down, the connection from a client was rerouted to a server with a lower priority. When the higher priority server returned to service, the connection to the lower priority server persisted. Beginning with PI Server 2018, when a higher priority server goes down and then comes back up, the connection from the client automatically detects the change in status and restores the connection to the higher priority server.

1. Open PI Connection Manager. From most clients, choose File > Connections.

2. Double-click the collective name to open the Collective Member Information dialog box.

3. Click a server to view its properties.

4. In Priority, specify the desired connection order for the selected server.

   PI SDK attempts to connect to servers in the order specified. PI SDK never connects to servers with a priority of -1. By default, the primary Data Archive server has a priority of 1.

5. Click Save.

6. Click Close to close the Collective Member Information dialog box.