Browse Prior Art Database

Cable Tester

IP.com Disclosure Number: IPCOM000081344D
Original Publication Date: 1974-May-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Formica, G: AUTHOR

Abstract

This logic circuit tests n-wire cables for continuity, shorts between wires and for inversion of wires.

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Cable Tester

This logic circuit tests n-wire cables for continuity, shorts between wires and for inversion of wires.

Control logic 1 sends a command signal for sequentially closing one electronic switch of set 2 at a time, putting under test one corresponding wire of the cable. With the same sequence control, logic 1 conditions the AI circuit of set 3 corresponding to the wire under test. Current generator 4 feeds a constant current Ic to the wires of the cable through the closed electronic switch.

When the wire under test is open, the voltage at point P is greater than V1 = Ic (Rw + Rc + Rr), where Rw is the resistance of a single wire, Rc the resistance of contact at the connector pin and Rr a fixed reference resistance. Threshold detector 5 detects this condition producing a signal for control logic 1, which stops the sequential closing of electronic switches 2, turns on the OPEN indicator and indicates the number of the open wire on numeric display 7.

If a short is present in the cable because k wires are touching, the voltage at point P is equal to or less than V2 = Ic (Rw + Rc/k + Rr/k). This condition is detected by threshold detector 6, which generates a signal for control logic 1. As in the previous case, control unit 1 stops the closing sequence, indicates the number of the wire in short on numeric display 7 and turns on the SHORT indicator.

If an inversion of wires is present in the cable, i.e., wire a is inverted with wire n, when control logic 1 clos...