Modbus Training

Course duration: 1 day


Course Overview

Modbus has become a widely used field bus throughout the world since its introduction in 1979. It is a serial-based communication protocol and has two serial variants - Modbus RTU and Modbus ASCII. It is often used in conjunction with other field buses via field bus gateways but is ideal in networking controllers, sensors, actuators and binary terminal devices in the automation environment in a cost-effective manner. With the advent of Ethernet networking, MODBUS was extended to this medium and MODBUS TCP was added to the portfolio.


The course begins with an introduction to what Modbus is and its history. We see where Modbus fits in as a digital communications system and the additional flexibility of Modbus TCP. For distributed I/O we see how it provides simplification and easy expansion of both digital and analogue signals.


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Course Outline

As Modbus can be implemented over multiple transmission mediums we learn about the physics behind its implementation over the copper wire medium in terms of the following subjects:


  • Electrostatic Interference

  • Electromagnetic Interference

  • Earthing

  • Reflections

  • Signal Attenuation

  • Repeaters

  • Terminations

  • Modbus TCP


We look at Serial Modbus over RS485, RS232 and RS422 and also wireless and remote monitoring (GPRS) solutions (also for Modbus TCP). The course then covers the Modbus protocol versions in more detail:


  • Modbus RTU

  • Mobus ASCII

  • Modbus TCP


Students will learn the Modbus Message frame formats and how to decode Modbus messages. It is also explained how Modbus operates as a Master/Slave protocol.


Finally, the course takes a practical look at memory access, how data is stored, data types, "Endianness", bit and byte significance and bit masking.


Each trainee will receive both theoretical and hands-on practical training with a number of tutorials. In the practical exam, the trainees will decode messages, use a Modbus simulator to manipulate register data, read in real values from temperature and proximity sensors, control a drive and transmit data wirelessly using Modbus TCP.



We limit training groups to a maximum of 8 people. Training will only take place if more than 4 people have booked.



The Johannesburg based course will be run from the IDX offices in Fourways.

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IDX Academy Contact Details

+27 (11) 548 9960
academy [at] idx.co.za