A Windows Modbus Slave Simulator

Over the years, we’ve worked with many devices and systems that need to talk Modbus and having a good, flexible simulator to test against is an absolute must. We developed Winmodbus to make this process as simple and efficient as possible. As well as being able to simulate all the common modbus messages and number formats, Winmodbus breaks down the cryptic modbus message format into plain language allowing you to work out what’s going on and making troubleshooting problems much easier. We’ve also built in some failure simulation so you can code your application to cope with common failure situations.

  • Understand what’s going on with Message Explanations, Field Breakdowns and Custom Register Naming.
  • Ethernet TCP and Serial RS-232 / RS-485 support.
  • Protocol Simulator for Modbus RTU, TCP and ASCII.
  • Slave Failure Testing Functions – CRC Fails and Link Breaks
  • Link data to Excel or other packages that support DDE
  • Highly compact. Quick Windows Install/Uninstall.
  • Designed, written and tested in-house by Windows Programmers  with years of Modbus experience.
  • “Simple, Elegant, Efficient & Reliable”

Winmodbus is a Windows Desktop application with a simple installer/uninstaller. It will run on Windows XP, Vista, 7, 8, 8.1 and 10.

Customer Quotes

“I’ve been browsing around for a good ModBus slave simulator for a while and tested several. Yours is by far the best I’ve tried, it’s very user friendly, easy to connect, professional looking, lots of information right in the main window and it works. “

“very powerful; way cool”

“WinModbus is really saving me some time doing some testing for an upcoming integration, thanks for your hard work!”

“a very useful tool”


Trial Version here

The evaluation version is fully functional for 14 days. After this, please buy a copy to support more development.


Price: £62.50 (approx $99)

Includes lifetime upgrade to all future versions and e-mail support.


3 thoughts on “WinModbus

  1. I downloaded the evaluation copy and installed.
    Clicking setup/communication the software waiting more than 1 minute before displaying the communication windows. It is quite confusing. My OS is Win7Pro.
    Any suggestion?

  2. My previous experince was gained with PC not connected to the company network.
    If my PC is connected to my company network it takes about 50 minutes!!! to get the communication window displayed.
    Please note I have about 40 virtual serial port installed on my PC (I have DigiOne IAP serial to Ethernet converters to communicate with devices having only serial port through the Ethernet network).
    My suspition is that the long waiting time somehow related to the virtual ports.
    Please not also the WinModbus did not recognise all my virtual serial ports. In the dropdown list I can see only 11 of them.

    1. Thank you for the bug report. WinModbus currently detects serial ports just by trying to open them. I guess with some virtual serial ports, a long delay may be possible if the ports are not present or in use. We are looking at other ways to detect serial ports and a new version should be available in a day or two.

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