Modbus Simulator Software

A useful Modbus master simulator designed primarily to help developers of Modbus slave devices Modbus Poll is a Modbus master simulator designed primarily to help developers of Modbus slave devices or others that want to test and simulate the Modbus protocol. With the multiple document interface you can monitor several Modbus slaves and/or data. Witte Software products. Modbus Poll is the very popular Modbus master simulator for test and debug of your slave devices. Supports Modbus RTU/ASCII and Modbus TCP/IP. New version 9 with Real time Charting. Requests from 2 slaves ID's. Quick start guide.

Data Communication Test Software

Simply Modbus TCP Client

Modbus TCP Client Software

Free downloadruns indemo modewith full functionality.

Demo mode allows sending and receiving six request messages.

The demo can be restarted to send and receive more messages.


Functions as a Modbus TCP Client (Master) or Modbus RTU-over-TCP Master

Connects to TCP Server (Slave) devices using Modibus TCP or Modbus RTU protocol

All information is entered and displayed in one window.

Supported Register Function codes:

Function CodeActionTable Name
04 (04 hex)ReadAnalog Input Registers
03 (03 hex)ReadAnalog Output Holding Registers
06 (06 hex)Write singleAnalog Output Holding Register
16 (10 hex)Write multipleAnalog Output Holding Registers

Supported Coil Function codes:

Function CodeActionTable Name
02 (02 hex)ReadDiscrete Input Contacts
01 (01 hex)ReadDiscrete Output Coils
05 (05 hex)Write singleDiscrete Output Coil
15 (0F hex)Write multipleDiscrete Output Coils

Change the reply data types and byte and word ordering with a click
to determine the format of a reply string without having to send another message.

Supports multiple data types in the same message.

Supports Standard Modbus and Enron Modbus

Supports 2 byte slave IDs

A notes column allows labeling the results

Allows saving and restoring settings in Configuration Files.

Write window allows writing single and multiple values

Save the Byte History Log to a text file

Log Data to a tabbed text file

and more...

See the online manual

See the tutorial to Learn about Modbus and How it Works


Modbus Simulator Software

Free Download

All unlicensed programs run indemo mode

with full functionality.

Demo mode allows sending and receiving six messages.

The programs can always be restarted to reset the demo
and send and receive more messages.


Compiler 14
70.7 MB - click to download



Compiler 7
8.62 MB - click to download


Compiler 5 - For windows XP

No Install Program. Just download, unzip and double click the exe file.
1.65 MB - click to download

Known Issue: Some users experience version 1.4 quitting by itself
or requiring an 'end task' to close properly.



Download the demo and try before you buy.

QuantitySimply Modbus
TCP Client
1 license
for 1 user or 1 PC
2 licenses
for 2 users or 2 PCs
site license
unlimited installations
at one location
within a single company

Prices in US dollars.

Combine purchase with other programs for savings.

Modbus Rtu Simulator Software Free Download

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Free Modbus Simulator Software

Copyright © 2020 Simply Modbus. All rights reserved

diagslave is a simple command line based Modbus slave simulator and test utility.diagslave is using the FieldTalk Modbus driver.

Diagslave binaries are available for the following operating system platforms and architectures:

  • Windows PCs
  • Linux PCs
  • Raspberry Pi, BeagleBoard and other ARM based Linux devices
System Requirements
  • Windows (x86, x64)
  • Linux (x86, x86_64, Arm64 Aarch64, Arm32 eabihf)
License This program is free; you can use it and redistribute it under the terms of the accompanying License document.



Download into a folder and extract the zip archive.The diagslave.exe command must be run from a Command Prompt:


Download into a folder. Then unpack the tarball:The tarball contains multiple binaries for different CPU architectures.Run the version matching your system from the command line.Example for Raspberry Pi:


Usage Examples

To get help on usage run the following command:To run a Modbus RTU server at 9600 baud on COM1 run:To run a Modbus/TCP server on Ethernet run: