RS-232 and RS-422 Converter for an IBM Personal Computer
Original Publication Date: 1985-Nov-01
Included in the Prior Art Database: 2005-Feb-19
An arrangement is disclosed that allows an IBM Personal Computer (PC) family of products to communicate to an asynchronous device via the RS-232 or RS-422 ports. Both modes of communication can operate simultaneously. Presently, the PC only supports RS-232 asynchronous communications to external devices. Applications have arisen that require RS-422 control of special process hardware. The PC has all the process control requirements, except long distance and multi-drop communication capabilities. The RS-232 asynchronous port can only communicate to one device that is not over 165 meters away. By adding the RS-422 support, the PC is capable of communicating to 16 devices on one line with the furthest device 4,000 meters away. All the power required can be obtained from the PC's bus as presently designed.