Introduction to Modbus Protocol

What is Modbus?

Introduction to Modbus Protocol

Features

What is Modbus/nModbus?

 

What is Modbus protocol ?

Modbus is a communication protocol developed by MODICON Inc. in 1979. It's a standard, truly open and the most widely used network communication protocol in industrial automation field. SCADA and HMI software can easily integrate serial devices together via Modbus protocol.
What is Modbus/TCP protocol ?

Modbus/TCP protocol is a variant of Modbus protocol. It was developed in 1999 to allow Internet community access Ethernet devices.
What is nModbus ?

nModbus is a C# 3.0 implementation of the Modbus protocol. It is developed and maintained on a voluntary basis and provided free of charge. 
ICP DAS verified and improved the DLL based on the official released NModbus_net-2.0_1.11.0.0-source.zip.
Programmers can use the DLL released by ICP DAS to develop a Modbus application for regular Windows based PCs or WinCE based devices. The DLL features
  • Modbus/RTU Master/Slave
  • Modbus/ASCII Master/Slave
  • Modbus/TCP Master/Slave
  • Modbus/UDP Master/Slave

Download the DLL and Demos

What software supports Modbus and Modbus/TCP protocol ?

Most of SCADA ( Supervisor Control And Data Acquisition ) and HMI software support Modbus. For example: Citect, ICONICS, iFIX, InduSoft, Intouch, Entivity Studio, Entivity Live, Entivity VLC, Trace Mode, Wizcon, Wonderware... etc
What are the benefits of using Modbus and Modbus/TCP protocol ?

1. Openness, no license fees.
2. Widely supported by SCADA and HMI software
3. Easy to use
4. Easily integrate variant devices
5. Low development cost
6. Widely knowledge resource

Modbus Resource ?

http://www.modicon.com
Web page of original Modbus protocol inventor, MODICON Inc.

http://www.modbus.org
A community for Modbus users of Modbus users

http://www.modbustools.com
ActiveX component and test tools to communicate with equipments via Modbus (RTU/ASCII) or Modbus/TCP

http://ftp.icpdas.com/pub/cd/8000cd/napdos/modbus/modbus_master_tool/
http://ftp.icpdas.com/pub/cd/winpac/napdos/wp-8x4x_ce50/system_disk/tools/modbus_master_tool/
ICP DAS provides a test tool of Modbus connection.