Abstract: A transmission line for carrying digital signals is provided with auxiliary line drivers at the receiver end, which are used in combination with the data line driver at the transmitting end to apply a sequence of sets of test voltages onto the line. The voltage resulting at the receiver input is used to detect open signal conductors and/or shorts in the receiver.

Abstract: A digital data transceiver comprises a conventional push-pull driver and a novel receiver. The transceiver can drive data to and simultaneously receive data from a transceiver of like kind via the same communication line. A series resistor is situated between the driver's output and the communication line. The resistor has equivalent resistance to the characteristic impedance of the line in order to prevent undesirable reflections on the line. In the receiver, the driver's output is divided in half by a resistor voltage divider for input to a differential current mechanism. The differential current mechanism has a differential current switch and a feedback circuit. The differential current switch compares the signal levels at both ends of the series resistor to derive an output for the receiver. The feedback circuit provides feedback to the differential current switch to increase the noise margin.