Fault:

When using the Modbus TCP driver to a unitronics Vision PLC, socket error 10061 is reported in modbus.txt.

Cause:

The error 10061 means that the socket has been blocked by the PLC. This has been found to be caused by closing a socket and then opening another socket straight after the close operation.

Solution:

The driver was changed (24/10/2008) to have a delay in between closing a socket and opening it again.
This fixed has been tested with a unitronics PLC.

Note: Modbus errors are recorded to modbus.txt in the jobs setup folder. However if the same socket error is reported repeatedly, then only the first error message will be saved. Another message will only be saved if the network error code changes or microscan is restarted.

Ref: JW Seeka Main Road