Step 1.2. Use the Trace Log

Following is a sample list of problems that can be diagnosed with the trace log. The list is not exhaustive. It is intended as a guide only.

Client connection problems. Use the log to verify if the OPC Server received the client's request to connect. This request may have been blocked by DCOM security.

DCOM security authorization problems. This can occur if a client can connect to the OPC Server but cannot access server objects. For example, the client can connect to the OPC Server but cannot create an OPC group.

Validate the OPC items requested by a client and verify the Item ID syntax.

View the sequence of OPC interface requests to verify the correct operation of a client.

Verify that a client gracefully disconnects.

Troubleshoot subscription problems (i.e. callbacks into the client by the OPC Server when data changes are reported). In this case, the client is able to perform synchronous and asynchronous read and write requests but cannot receive subscription updates. This may be due to a DCOM security authentication problem on the client machine. The client is unable to authenticate the OPC server.

See how a client organizes OPC groups and OPC items within groups.

More information

OPC Connection trace logging.