Select [Comms] from the [Setup] menu.

Enter the modbus address WinModbus should reply to. Your options are:

  • Leave it blank - Winmodbus will reply to ALL valid messages
  • A single address, e.g. 125
  • Multiple addresses separated by commas to limit the addresses to be replied to, e.g. 1, 2, 3.

Select the protocol:

  • ModbusTCP (6 byte header at the front of every message and no CRC on the end)
  • Modbus RTU (No Header, CRC on the end)
  • Modbus ASCII

Select Network or Serial and enter the relevant setup information for the transport you have chosen.

For network, the standard ModbusTCP listen port is 502. For serial, you can set baud, parity and stop bits here as well as serial port. Data bits is automatically set depending on whether you are using Modbus ASCII (7) or not (8).

WinModbus only displays the currently available serial ports.If your serial port isn’t appearing in the list, ensure it is not in use by something else.

Note: You can mix Modbus TCP/RTU with serial/ethernet links which is useful for scenarios where you may be using a network terminal server to talk to a serial device.