PyModbus Error: 'ModbusIOException' - Troubleshooting Guide

This error occurs when the Modbus server is unable to decode the request message sent by the Modbus client. It could be due to a communication issue between the client and server, or an incorrect message format or syntax.

To troubleshoot this error, you can try the following:

1. Check the connection between the client and server to ensure they are properly connected and configured.

2. Verify that the message format and syntax are correct. You can refer to the Modbus specification to ensure that the message format and syntax are correct.

3. Check the Modbus server logs for any error messages or warnings that may provide more information about the issue.

4. Try restarting the Modbus server and/or client to see if the issue resolves itself.

5. If all else fails, contact the Modbus vendor or developer for further assistance.