Test program for MODBUS

Modbus RTU and TCP terminal

The program is intended for testing purposes when Modbus protocol is applicable. Since ModBus has wide usage very often installers and engineers have to use it. Normally devices that have modbus protocol comes with manufacturer interface and software, but often is needed an external verifying program. That is the purpose of this simple modbus terminal. It is free-ware and can be download from section Downloads

This program is tested under Windows 2000/XP/Vista/Windows 7/Windows 8/Windows 10. Will work both on 32-bit and 64-bit platfroms.

user manual

General Information

GModbus can do the following:

  • Communication protocol Modbus RTU and/or Modbus TCP
  • read of one or many Input registers
  • read of one or many Holding registers
  • read of records (strings in general case)
  • automatic read, range 100ms - 10 000 ms
  • write of single Holding register
  • write of multiple Holding registers
  • data represent in:
  • 16-bit hex
  • 16-bit integer (decimal, 1 register)
  • 32-bit integer (decimal, 2 registers)
  • 64-bit integer (decimal, 4 registers)
  • 32-bit float (2 registers, IEEE)
  • 8-bit char
  • full log of the communication in hexadecimal style

Program supports both Modbus RTU and TCP, but can not work simultaneously on two different connection points.

Received data can be exported in CSV file. Log data can printed or saved in text file.

When the program starts, it do not opens serial port or TCP port. The user must manually connect to the chosen serial communication point. Set-ups are saved in *.ini file with same name as the program. Saving is automatic - when the user close the program.

This is first version, tested from us, and we will be grateful for feedback. Any reasonable comments and suggestions for adding/changing functions are welcome and will be done free.