The reason for canceling the communication cable is generally caused by incorrect transmission settings. This paper will introduce the troubleshooting method of communication fault between computer and Mitsubishi plc.

Poor contact of communication cable interface

The communication cable interface is not in good contact, which is probably the communication interface you mentioned. Frequent plugging and unplugging will cause this situation.

Communication board problem

I wonder if your industrial computer (computer) is equipped with a communication board. If so, there may be something wrong with the communication board. If not, see if there is a problem with the parameter setting or operation of the monitoring software.

Baud rate setting problem

Has the baud rate in the system block of PLC program been changed, and it can't be connected after downloading? If the baud rates are consistent, connect (in software and PLC). If not, please call Siemens technical support.

Transmission setting problem

Solution: Open the Computer Device Manager → Port Item. Check the com number of the port actually occupied by the usb programming cable. In the transmission settings of programming software, the com number must be set to be consistent with the com number of the actually occupied port, so as to ensure the success of communication.