Modbus Rtu Cable

Modbus is a data communications protocol originally published by modicon now schneider electric in 1979 for use with its programmable logic controllers plcs.

Modbus rtu cable.

Under ideal conditions cable lengths of 4000 ft. Correct termination of the shield drain to a dedicated ground terminal or chassis should provide noise rejection. Go back to modbus rs485 cabling rules 8. Of slaves also depend on the data logger specification.

The industrial rs 485 cables are designed with low capacitance ideal for long distance applications. Modbus is popular in industrial environments because it is openly published and royalty free. In environments where excessive interference. The cable shield must be earthed only in one point.

In order to avoid signal reflections a 120 ohm termination resistance must be fitted on each end of. Maximum length is 100 m 328 ft. 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. Modbus has become a de facto standard communication protocol and is now a commonly available means of connecting industrial electronic devices.

However the cable recommended for long lengths can be expensive so if there is an existing ethernet infrastructure in place it may be more affordable to convert from bacnet ms tp or modbus rtu over rs 485 to bacnet tcp ip or modbus tcp ip over ethernet. So if you desire data fast and you want to come into the 21st century then modbus tcp ip is the way. The atv212 drive includes a line termination as standard. Normally this connection is made at one end of the main cable.

The maximum length of the communication cable should be no longer than 800m recommended the maximum number of devices that can be connected over this network can be 32 for modbus rtu including the master device trackso data logger in our case apart from the network no. Modbus tcp ip is simply the modbus rtu protocol with a tcp interface that runs on ethernet. Cable termination rs485 modbus rtu line line bias when the rs485 network is not being actively driven by a device the differential pair is more susceptible to interference and noise. Modbus serial link connection is carried out using rs 485 double shielded twisted pair cables supplied without connector reference.

Modbus cable interface quickly and easily with most existing plant control architectures by using belden cabling for modbus.