The 3 most common modbus type used today.
Modbus rtu cable type.
Modbus is a data communications protocol originally published by modicon now schneider electric in 1979 for use with its programmable logic controllers plcs.
For example belden 3105a cable can be specified but different types of cable with equivalent characteristics can be used.
In modbus protocol one master communication with many devices approx 240 device.
Modbus protocol is a messaging structure developed by modicon in 1979 used to establish client server communication between intelligent devices.
Modbus rtu is an open serial rs 232 or rs 485 protocol based on master slave or client server architecture.
With its open and simple specifications the modbus protocol is widely used to control device communications in industrial applications.
As indicated in the following table modbus modes and functions differ depending on cable type.
Go back to modbus rs485 cabling rules 5.
Modbus has become a de facto standard communication protocol and is now a commonly available means of connecting industrial electronic devices.
Modbus cable interface quickly and easily with most existing plant control architectures by using belden cabling for modbus.
Modbus has been a standard for interfacing remote i o and plcs into the process dlc system for over 20 years allowing most legacy control systems to interface easily with modbus.
The cable to be used is a shielded twisted pair telephone type.
The protocol interconnects field equipment such as sensors.
The twin consists of two conductors that are twisted together.
One example of such cable is belden 3105a.
But any cable with similar characteristics can be used to connect all the devices together.
Here describe a difference between modbus ascii vs modbus rtu vs modbus tcp ip below.
Modbus is popular in industrial environments because it is openly published and royalty free.
The wattnode bacnet and modbus meters communicate using rs 485 tia eia 485 a half duplex differential signaling at 9600 19200 38400 and 76 800 baud.
1 modbus ascii 2 modbus rtu based on serial communication like rs485 rs422 rs232 3 modbus tcp ip based on ethernet.
Type of cable to use.
For modbus communications a shielded and twisted pair cable is used.
