Modbus Rs485 Cable Specification

Rs 485 cable specification guide abstract.

Modbus rs485 cable specification.

Modbus specifications and implementation guides. 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. For modbus communications a shielded and twisted pair cable is used. 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 standard is jointly published by the telecommunications industry association and electronic industries alliance tia eia. Rs 485 also known as tia 485 a or eia 485 is a standard defining the electrical characteristics of drivers and receivers for use in serial communications systems. General overview of modbus documents. The cable shield must be earthed only in one point.

This document comes in complement to the document called modbus application protocol specification. Type of cables to use. Go back to modbus rs485 cabling rules 8. Over short distances 100 ft.

From power limited tray cable pltc and plenum cmp rated cable to low smoke zero halogen cable you get the ideal solution for your automation network. Normally this connection is made at one end of the main cable. But any cable with similar characteristics can be used to connect all the devices together. The proper method of wiring an rs 485 network is described with recommendations for twisted pair cabling and correctly locating termination resistors.

In chapter 5 different implementation classes are defined for modbus serial line. Go back to modbus rs485 cabling rules 7. One example of such cable is belden 3105a. Please review the following license agreement before down loading any modbus protocol or related documents from this web site.

Specification of a class is the sum of requirements that a device must respect in order to belong to that class. Electrical signaling is balanced and multipoint systems are supported. The industrial rs 485 cables are designed with low capacitance ideal for long distance applications. Earth connection of the shield.

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