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The Programmer’s Toolkit

Dec 13, 2011 5:28 PM, By Patrick Barron

The must-have adapters, connectors, cables, and other accessories to get the job done.


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Serial cables and serial tester

Cables

I also include an assortment of video, audio, and control cables in my laptop bag. Here’s a rundown of the cables that I carry:

· VGA-to-VGA cable with audio. This is used to connect a laptop with audio to a wallplate or other type of connector plate that has a VGA connector. Most systems have some kind of VGA signal, and a programmer will already have a laptop while working, so having a VGA cable provides a VGA source that can be used to test switching to a video display and the built in audio cable allows testing of the audio system.

· 1/8in.-mini-stereo-audio-cable-to-dual-RCA; this cable allows an MP3 player or laptop to be connected to RCA audio connectors to provide an audio source to a wallplate with stereo RCA connectors.

· 1/8in.-mini-3-pin-to-4-pin Phoenix; this connector is used to load certain types of wireless Crestron touchpanels. The 4-pin Phoenix connects to the master processor’s CresNet bus and the 3-pin mini connector plugs into the touchpanel to load files.

· 1/8in.-mini-stereo-audio-to-1/8in.-mini-stereo-audio, used to connect an audio player such an iPod or other MP3 player or even a laptop to an audio jack on a computer input plate or wallplate

· 9-pin-male-to-1/8in.-mini-3-pin cable; this type of cable is used to load files to an older generation AMX viewPoint touchpanel.

· RJ-11-to-RJ-11 on retractable spool, used to connect phone jacks to phone plugs on an audioconference system. The retractable spool holds a 6ft. cable in a small space.

· 9-pin-male-to-9-pin-female straight-through cable, used as an extension cable for serial devices. This cable can be used to connect from a laptop to certain Crestron processors and certain audio DSPs. It can also be used as a test cable to verify control of RS-232 equipment. If a serial cable is suspected to be bad or wired wrong, having a known good cable to connect from the RS-232 port on a central processor to the equipment being controlled can verify that the code is good and the problem lies in the cable.

· 9-pin-male-to-9-pin-female null cable; this is a serial cable with opposite genders on either end and the transmit and receive pins crossed inside the cable. It can be used to communicate from a laptop to several types of AMX processors. It can also be used to test a bad serial cable. Often when making a control cable, it is not known if the connection should be straight through or if it should have the transmit and receive pins reversed. By having both the straight-through serial cable and the null serial cable, both types of possible connections can be tested and the problem cable can be fixed.

Network cable tester

Cable Testers

Cable testers are another part of the essential tools that I keep in my bag. There are two primary testers that are extremely useful. One is an RS-232 tester. This type of tester has 9-pin connectors on each end and lights to indicate status of various pins on each end. With the increased use of Cat-5 extenders for video sources, it has become more valuable to have a Cat-5 tester as part of the bag of tools. In my bag I keep a tester that allows me to check simple PASS/FAIL to find faults, and it also detects good connections, open wires, crossed wires, and split pairs. The particular tester I have also checks BNC 50Ω and 75Ω cables.

While not a tester, one item that I use frequently is a cheat sheet that I picked up from Extron showing the proper way to wire balanced and unbalanced audio cables. Most installers might have this knowledge memorized, but as a programmer, I don’t wire audio cables every day and having a sheet as a reminder has helped me on many occasions to identify a problem when testing an audio system.

A control system programmer is asked to perform many complicated tasks while commissioning a control system. Having a laptop alone is not always sufficient to fully test all the functions in a control system. Having the proper tools in your bag can allow the programmer to finalize all aspects of testing before the final walkthrough and signoff with the end-user. The programmer can look good at the end of the job by finding all of the problems with the control system software and having the proper tools to troubleshoot and fix those problems.



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