Cable Tester
Because cabling is so vital to powering lighting gear, as well as for making control signal connections, you should have some kind of cable tester in your tool kit that is appropriate for the kind of cabling you use. Of course, you can always use your DVM/VOM for testing continuity between the two ends of a cable, but it's not as convenient to use for multi-part cables such as cat5 cable, which has four pairs -- 8 wires inside the protective sheath. The most common wiring scheme is "T568-B", shown below as if you looked at the bottom of the plug with the metal connectors pointing upward:
One simple tool is a network cable tester for cat5 type cable. It also works fine with cat5e, cat6 and cat6e cable as those are just higher grade versions of the common, 8-wire cat5 cable. A network cable tester doesn't have to be expensive -- this one can be found for less than $10 in stores as well as on eBay:
Simply plug the cables into the ends and flip the power switch -- the diagnostic LEDs light in on both tester sides simultaneously as each cable is tested. This tester makes it easy to see when a cable is reversed or out of order. If one of the LEDs doesn't light at all, it means that either one (or both) of the plugs is not making good contact on the wire on that pin number, or possibly that there's a break in the wire somewhere in the length of the cable.
When an LED comes on out of order, a close examination of the colors of the wires in each plug should tell you which plug is correct and which is wrong: cut off the bad plug and attach a new one.
When an LED doesn't com on at all, try recrimping both ends of the cable and retest. Sometimes that fixes the problem. If not, try a close examination of both plugs to see if you can discern which one might be bad. If you can't tell, well, you have a 50-50 chance on selecting the bad plug: cut one off, replace it and test the cable again. If you end up replacing both plugs and still the same line doesn't come on, the cable likely has an internal break somewhere. Those are much harder to find, and it's usually much faster just to replace the cable.
Another kind of tester is one designed specifically for the hobby that's designed to test cabling for remote SSRs and can also test the SSRs themselves by sending a control signal to them to turn them on. This unit tests connections on pins 1, 2, 4 ,6, 7 and 8, the only pins that are normally used to control SSRs:
- NOTE: Before you toss the bad cable out, remember that controllers, SSRs and communication gear don't always use all 8 wires in a cat5 cable. If the "dead" line is one that's unnecessary anyway, the cable can still be useful! So it pays to know how your equipment interconnects -- it can save money!
Making a Data Cable
- Making a correct cable is likely the #1 problem for newcomers to this hobby and the first cause of failure when something doesn't work. There's no rocket science involved here, it's just a simple, good electrical connection, but you must take care to do it carefully and well. You essentially connect the source of the signal, i.e. the sending equipment to the proper RJ45 pin that goes to the receiving equipment, observing the proper ground and data signal lines for the kind of connection you're making. That's all it is.
- You'll need an RJ45 crimper tool to fasten wires to RJ45 plugs. There are many flavors of crimpers, prices vary widely and are available in stores on on eBay:
- The trickier part can be the plastic RJ45 plugs themselves because some are designed to work with solid cat5 wire while others are designed for stranded cat5 wire. To check the kind of wire that you have, strip off a bit of the insulation of some of the internal wires inside your cat5 cable to discover whether each has only one, solid wire inside or whether there are many thinner wires (stranded type) that make up each of the 8 internal wires. Then purchase the plugs for the kind of wire you have. Plugs are rather inexpensive and many DIYers keep both types on hand so they're prepared for both types.
Common connections for cat5 cables
- Controller to remote SSR
- Pin # - wire color - function
- Pin 1 - orange/white - +5v power
- Pin 2 - solid orange - channel A signal (of a 4-channel SSR)
- Pin 3 - green/white - no connection
- Pin 4 - solid blue - channel B signal
- Pin 5 - blue/white - no connection
- Pin 6 - solid green - channel C signal
- Pin 7 - brown/white - ground return to controller (optional, not all controllers or SSRs support this)
- Pin 8 - solid brown - channel D signal
- Computer to controller - Renard RS-232 connection format
- Pin # - wire color - function
- Pin 1 - orange/white - Ground
- Pin 2 - solid orange - Ground
- Pin 3 - green/white - no connection
- Pin 4 - solid blue - RS232 signal
- Pin 5 - blue/white - Ground
- Pin 6 - solid green - no connection
- Pin 7 - brown/white - no connection
- Pin 8 - solid brown - no connection
- Computer to controller - Renard RS-485 connection format
- Pin # - wire color - function
- Pin 1 - orange/white - Ground
- Pin 2 - solid orange - Ground
- Pin 3 - green/white - no connection
- Pin 4 - solid blue - Data- (may be marked T- or D- or B)
- Pin 5 - blue/white - Data+ (may be marked T+ or D+ or A)
- Pin 6 - solid green - no connection
- Pin 7 - brown/white - no connection
- Pin 8 - solid brown - no connection
- Computer to controller - Renard DMX connection format
- Pin # - wire color - function
- Pin 1 - orange/white - Ground
- Pin 2 - solid orange - Ground
- Pin 3 - green/white - no connection
- Pin 4 - solid blue - Data-
- Pin 5 - blue/white - Data+
- Pin 6 - solid green - no connection
- Pin 7 - brown/white - no connection
- Pin 8 - solid brown - no connection
Here's a link to an excellent source of documentation on making Renard Data Cables Renard Data Cables