COM-485 from $210
RS-485 Network and Communications Board
For IBM PC/XT/AT and Compatibles

The COM-485 board allows IBM PC's to be networked over the RS-485 bus. Unlike the RS-422 bus which allows multiple receivers but only a single transmitter on the bus, the RS-485 allows multiple transmitters and receivers to communicate over a 2 wire bus allowing a "party line" network configuration. The COM-485 will allow up to 32 different driver/receiver stations to communicate at 56 kilo baud and stations can be located up to 4000 feet away from each other. The COM-485 can be set up as a COM1: or COM2: standard serial interface port, or can be set at any other base address/interrupt level combination desired by the user. Applications for the COM-485 include networking instruments, scanning and updating various use input and output devices (such as CRT's, keyboards, etc) and any other communication application that require more than one device to be simply and inexpensively networked to a personal computer.