Simply Modbus logo Modbus tester for serial communication diagnostics







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Data Communication Test Software

Simply the easiest way to test and debug Modbus systems


Simply Modbus Master

Modbus RTU Master and Modbus ASCII Master Software

RTU Master screenshot


 Functions as a Modbus RTU Master or Modbus ASCII Master

 Connects to RTU or ASCII Slave devices using the Modbus protocol

All information to send and receive messages is displayed in one window.

Logs the messages in a Communication Log.  SAVE LOG allows saving to a text file.

LOG DATA starts logging the result values in a tab-delimited text file

       Supported Function codes:

Function Code Action Table Name
01 (01 hex) Read Discrete Output Coils
05 (05 hex) Write single Discrete Output Coil
15 (0F hex) Write multiple Discrete Output Coils
02 (02 hex) Read Discrete Input Contacts
04 (04 hex) Read Analog Input Registers
03 (03 hex) Read Analog Output Holding Registers
06 (06 hex) Write single Analog Output Holding Register
16 (10 hex) Write multiple Analog Output Holding Registers


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

Supports multiple data types in the same message.

 Supports Standard Modbus and Enron Modbus

Can use RTS delay (required for some radios)


Supports 2 byte slave IDs

A notes column allows labeling the results

Allows saving and restoring the settings in a Configuration File.

Write window allows writing single and multiple values

Save the Communication 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


Free Download

runs in demo mode with full functionality.

Demo mode allows sending and receiving four request messages.

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


Both versions are designed for Windows XP. 

Version 7 and higher works for most users in Windows7 or 8 using XP compatibility.


Compiler 5 - For windows XP

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

 Known Issue:  Some users experience version 6.4.1 quitting by itself or requiring an 'end task' to close properly.

If this is a problem, version 7.1.2 should help.


Compiler 7

Quick Install Program. puts a shortcut in the start menu.
8.60 MB - click to download



Download the demo and try before you buy.

Quantity Simply Modbus
1 license
for 1 user or 1 PC
for 1 program
2 licenses
for 2 users or 2 PCs
for 1 program
site license
unlimited installations
at one location
within a single company
for 1 program

Prices in US dollars.


Combine purchase with other programs for savings.


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