How to simulate a Modbus RTU slave on Windows 10 to communicate with a real Modbus master via USB to RS485?

[Khang14777]

Hi everyone,

I’m currently working on a project where I need to test communication with a real Modbus RTU master device (such as a PLC or an industrial controller). However, I don’t have a real Modbus slave device available at the moment.

Instead, I want to use my Windows 10 PC to simulate a Modbus RTU slave, and connect to the master device using a USB to RS485 converter.

My question is:

Are there any reliable Modbus RTU slave simulator tools for Windows 10 that can work over a USB-to-RS485 connection to communicate with a real hardware master?

I've seen tools like ModRSsim2, Modbus Slave by ModbusTools, and ModbusPal (Java-based), but I’m not sure if they support actual RS485 hardware communication and not just virtual COM port testing.

If anyone has experience simulating a Modbus slave this way, I’d appreciate your recommendations (especially free or open-source tools if possible).

Thanks in advance!