RS485 / Modbus RTU Wiring Standards – AlsoEnergy Support ContentsOverviewNetwork Wiring MethodCable TerminationIntroductionCable ConfigurationNetwork Wiring MethodNetwork LayoutCable Termination (general)Cable Termination (RS485/Modbus RTU Line Termination Resistor)Cable Termination (RS485/Modbus RTU Line Bias)See more on deckmonitoringesk 9 rules for correct cabling of the Modbus RS485 Connection PortConnection Between The DevicesMaximum Distance and Maximum Number of DevicesUse of RepeatersType of Cable to UseConnecting to The TerminalsEarth Connection of The ShieldTermination ResistanceConnection to Personal ComputerEach device has a communication port with two terminals, which are indicated for the sake of convenience as A and B. In these two terminals the communication cable is connected so that all the devices that take part in the communication are connected in parallel the ‘A’ terminals must be connected together and all the ‘B’ terminals must be connected together respectively order to avoid errors when many devices are connecSee more on electrical-engineering-portal Specification and Implementation Guide for MODBUS over PDF fileMODBUS over serial line specification and implementation guide V1.0 MODBUS In a 2W-or 4W-RS485 MODBUS Network, Signal and optional Power Supply Common DCE a MODBUS Device, for example a programmable controller adapter, Syntax of state diagram : RS485 Wiring Diagram from a 172JNN21032 Port 2 (RJ45) to RS485 Wiring Diagram from a 172JNN21032 Port 2 (RJ45) to an LULC031 Modbus Interface. Published date: 24 January 2018 Goals and Symptoms. The purpose of this resolution is to inform Momentum Processor and TesysU users how to wire an LULC031 to a 172JNN21032 Option Adapter via its Port 2 RS485 (RJ45 connector) for Understanding RS485: Wiring, Connection, Monitoring Ideally an RS485 system consists of a single linear cable (no branches) with 120 ohm resistors connected across the 2 wires at each end of the cable. RS485 can handle speeds of over 10 Mbits per second and line lengths of over 1 km. If you are operating anywhere near these values you must arrange your wiring close to the ideal.