Wire Map Testers and Tone Generators PDF

2.6.5 Wire Map Testers and Tone Generators Fully featured cable testers/certifiers are expensive. A simpler wire map tester device can be used to detect improper termination issues. To perform a wire map test, the base unit is connected to one end of...

2.6.5 Wire Map Testers and Tone Generators Fully featured cable testers/certifiers are expensive. A simpler wire map tester device can be used to detect improper termination issues. To perform a wire map test, the base unit is connected to one end of the cable and a remote unit to the other. When the test is activated, an LED for each wire conductor lights up in sequence. If an LED fails to light or does not light in sequence, there is a problem with the cable and/or termination. Wire map testers can identify the following problems: Continuity (open)—A conductor does not form a circuit because of cable damage or because the connector is not properly wired. Short—Two conductors are joined at some point, usually because the insulating wire is damaged, or a connector is poorly wired. Incorrect pin-out/incorrect termination/mismatched standards—The conductors are incorrectly wired into the terminals at one or both ends of the cable. The following transpositions are common: Reversed pair—The conductors in a pair have been wired to different terminals (for example, from pin 3 to pin 6 and pin 6 to pin 3 rather than pin 3 to pin 3 and pin 6 to pin 6). Crossed pair (TX/RX transposed)—The conductors from one pair have been connected to pins belonging to a different pair (for example, from pins 3 and 6 to pins 1 and 2). This may be done deliberately to create a crossover cable, but such a cable would not be used to link a host to a switch. Another potential cable wiring fault is a split pair. This is where both ends of a single wire in one pair are wired to terminals belonging to a different pair. This type of fault can only be detected by a cable tester that measures crosstalk. A network tone generator (or toner) and probe are used to trace a cable from one end to the other. This may be necessary when the cables are bundled and have not been labeled properly. This device is also known as a Fox and Hound. The tone generator is used to apply a signal on the cable to be traced so that you can use the probe to identify the same cable within a bundle or duct. Copyright © The Computing Technology Industry Association, Inc. All rights reserved.