PLCTalk Pick of the Week: Modbus Simulation Software

The PLCTalk forum pick of the week this week  is  about Modbus simulator software.
Capture from a Modbus Network
Capture from a Modbus Network


The question

  1. What software out there scans Modbus registers from a PC and provides confirmation of a good connection?
  2. Do any of the software options scan registers on a slave/node? ( automatic scanning inferred)

In a typical setup, the PLC would be connected to a computer with a USB -RS232 adapter or a USB-RS485 adapter.

4 Modbus Simulation Software options



This site seems to offer Modbus simulator and OPC tools. With the Modbus tool, there is an indication of a succesful connection. There is an evaluation version of the software downloadable. The full version is not free.


There seem to be several Modbus simulators and polling tools  offered here. This software is also not free. There seems to be a trial version that works for 10 minutes at a time for the first 30 days. This software includes options to log data to Excel and  text files. It is unclear if there is confirmation of ‘good connection’ provided per the original question.

There is also an option create a custom frame which might be useful for testing and debugging purposes.


This is a free, open -source project built on a framework called qt. New to me, interesting concept.  There is a bus monitor to see live frames. The latest update was in February 2016.  Seems promising mostly 4 and 5 star ratings from its 9 reviews.


Finally, the software I have used for Modbus TCP testing.  Schneider Electric has a free serial and Modbus TCP tester software. Unlike ModScan and some of the other options out there, this tool doesn’t include a live frame by frame view of communications.


In all cases, the option to automatically scan ‘live/open’ registers on a network didn’t seem to be something common on the market ( keyword:automatic). For Modbus networks with communications already up and running, the best bet would be to use a a communication viewer screen. This would show the frames on the network with addresses, commands and responses.

Link to the actual thread on PLCTalk.


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