Patent ID: 6720801
Filing Date: 2004-04-13
Classification: G06F

Abstract:
A data transmission monitoring apparatus for monitoring data transmission on an RS-232 bus having a transmit line and a receive line, said data transmission monitoring apparatus comprising:a first switching circuit connected to said RS-232 bus to receive data transmitted over the transmit line and the receive line of said RS-232 bus; a second switching circuit connected to said RS-232 bus to receive the data transmitted over the transmit line and the receive line of said RS-232 bus; a third switching circuit connected to said first switching circuit and an external computer to receive a positive voltage signal; a fourth switching circuit connected to said second switching circuit and said external computer to receive a negative voltage; said first switching circuit turning on said third switching circuit whenever the data transmitted over the transmit line and the receive line of said RS-232 bus has a positive voltage level; said second switching circuit turning on said fourth switching circuit whenever the data transmitted over the transmit line and the receive line of said RS-232 bus has a negative voltage level; said third switching circuit passing the positive voltage signal from said external computer through said third switching circuit to a receive input on said external computer whenever said first switching circuit turns on said third switching circuit; and said fourth switching circuit passing the negative voltage signal from said external computer through said fourth switching circuit to the receive input on said external computer whenever said second switching circuit turns on said fourth switching circuit.