Open Error (Code=10061) Occurs

Winsock error 10061 (Connection refused) occurs when the PLC rejects the connection request during communication setup.
This error is often caused by the PLC’s acceptance conditions or status, rather than issues in the communication path. Therefore, please prioritize checking the PLC settings and connection status first.

Causes

1. The listening port on the PLC is not open, or the settings do not match.
2. PLCs have a limit on the number of concurrent TCP connections. If another tool or system is already connected to the PLC port, new connections may be refused due to exceeding the limit.

Actions / Checks

1. Verify that the port number and protocol (TCP/UDP) match between the PLC and DeviceXPlorer OPC Server
2. Confirm that the PLC is in a connection-ready state (e.g., “always open” mode)
3. Check the PLC’s current connection status:
   • Are there any tools or systems already connected?
   • Are there unnecessary connections remaining?
4. Ensure that the PLC’s Keep Alive / timeout settings are properly configured
5. If necessary, restart the PLC or reset the Ethernet unit