The SER-COMi-SI-M is used to convert RS-232 signals to RS-422/485 signals. The converters provide instant connectivity to RS-422/485 communication devices for factory automation equipment, multi-drop data collection devices, barcode readers, time clocks, scales, data entry terminals, PC to PC long distance communications (up to 1.3KM) and serial communication in harsh environments. The SER-COMi-SI-M provide an industrial solution for applications requiring single node or multi-drop communications over short and long distances. In RS-485 half-duplex mode, SER-COMi-M and SER-COMi-SI-M also provides automatic data transmit/receive control For more details on product, Please refer to http://www.papyrus.co.il/1rs232rs422485metalopticalisolation.htm