Tester for an RS-422 Interface Cable
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-01
This tester verifies proper wiring of a four-conductor cable generally, and an RS-422 interface cable, in particular. If the cable test fails, the tester indicates the probable cause of failure. This test apparatus and procedure allows the user to verify the integrity of the interface cable by attaching the tester and running diagnostic software. A schematic of the tester circuit is shown in Fig. 1. The concept by which the tester operates is that the receive lines are connected to the send lines, and a computer attempts to read back the same data that it writes. The tester circuit allows the data to flow in only one direction so that the interchange of send and receive lines may be detected.