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Kepware Knowledge Base: Solution

Communication Diagnostics for a Channel Using a Serial Driver Shows TX But Not RX

Last Update: 11/7/2018

The Communication Diagnostics for a channel using a serial driver shows TX (transmit) but not RX (receive).

When this occurs, the problem could be with one or more of the following:

1. The RS485 converter.
2. Cabling.
3. The serial communication parameters (such as baud rate).
4. The Device ID or unit address.
5. An error in the request (such as, invalid memory address or a request for too much data) has caused the device to not respond.
6. The wrong protocol is being used (such as, using the Modbus ASCII Driver to communicate to a Modbus RTU device).
7. The device's communications port is turned off.

1. In the Communications tab of Channel Properties, try setting the server's Flow Control parameter to RTS Always.
2. Ensure that the cabling has been properly configured.
3. Ensure that the serial communication parameters have been set correctly.
4. Verify the Device ID or unit address.
5. Resolve any errors that occurred in the request.
6. Ensure that the right protocol is being used.
7. Ensure that the device's communications port is turned on.

The suggestions described above still apply when Kepware's serial drivers are in Ethernet Encapsulation mode. For more information, refer to Communications Diagnostics.

See Also:
Troubleshooting KEPServerEX

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