When multiple Card Readers have to be installed in cluster, RS 485 Bus topology is used. It uses 2 wire half duplex communication bus and the cable can be extended upto 1.2 km (of course using suitable screened, twisted pair 0.75 sq.mm. cable) from the computer Comport. Since, the PC does not support RS 485 port, a communication converter is required to convert the same to RS 232C. This converter is  termed as COMCON. It operated on 230V AC & is provided with a 2m Cable to connect it to PC Comport. There is a screw terminal provides for RS 485 cable connection.