InstallationM-Max Series Adjustable Frequency Drive MN04020003E—October 2013 www.eaton.com 45Serial Interface A-BThe following figure shows the connections of the serial interface and the position of themicro-switch for the bus termination resistor.Connection Terminals of the Serial Interface and Microswitch S4(Bus Terminating Resistor)The two control signal terminals A and B enable the connection of a shielded RS485twisted-pair cable.The bus terminating resistor required at the end of a data cable is integrated in the frequencyinverter and can be connected via microswitch S4.The network cable must have a bus termination resistor (120 ohms) connected at eachphysical end to prevent reflections and the resulting transmission faults.Two-Wire RS485 Connection(Slave = M-Max Frequency Inverter)The parameter definition of the serial interface is described in “Serial Interface(Modbus RTU)” on Page 131.1 2 3 6 7 8 9 10 25 244 5 13 14 15 16 18 20 22 23 26AI2 DO–GND DI4 DI5 DI6 AO DO+ R13 R14 – R24+10V AI1 GND 24V DI-C DI1 DI2 DI3 A B R21 R22LOGIC– +AI 1V mAAI 2V mARS 485– Term.S4 = RS485 (–)ABABPESPESSlave MasterRS485Modbus (RTU)S4120 ohmsRS485– Term
