Cat5 question - does it have to be to standard?

toodle_pipsky

toodle_pipsky

Minister of Silly Walks
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Toowoomba, Australia
A few years ago I made a heap of long cables using cat5 for SSRs. These are just straight through but I didn't follow any standard, I think off the top of my head they went brown, orange, green, blue. They worked fine for Grinch to SSR. My question is can I use these same cables for DMX and E1.31? My concern is because they are just made in their twisted pair there could be interferance issues. (Can you tell I'm lazy and don't want to re-crimp a whole bunch of cabling :)) Thanks.
 
DMX would probably work - I have a number of DMX cables that dont use a twisted pair at all, just plain 4 core cable. The issue is interference as there is a higher chance of interfering and altering the signal if it is not part of a twisted pair

e1.31, well in reality that would also work, but since there is no error correction, errors in the signal could cause unwanted things to happen with the lights.
 
As Dave alluded to, it's the pairing that makes all the difference. If the pairs are still in their correct positions, all is good.

I suspect that you meant that you have it wired like so:
PAIR 1
PAIR 1
PAIR 2
PAIR 2
PAIR 3
PAIR 3
PAIR 4
PAIR 4

It should be:
PAIR 1
PAIR 1
PAIR 2
PAIR 3
PAIR 3
PAIR 2
PAIR 4
PAIR 4

Running differential data (DMX or Ethernet for example) on "split pairs" will degrade the signal. DMX will probably still work over the relatively short distance in use on a Christmas display, but Ethernet can be badly affected.

* The pair numbers used above are just to differentiate each pair from the others.

** The colours used for each pair is not important in an electrical sense. There are two standards (T-568A and T-568B) that define the colours. Either can be used, but must be the same at either end of course.

*** Since DMX over CAT5 only uses the outer two pairs, the incorrectly wired cables would be fine as those pairs are not affected by the mis-wiring. The issue will be for Ethernet connections.
 
I'd give them a try before redoing them. Might be a lot of work. For nothing and if they act weird you know one thing to test right off the bat (swap with a regular cable).

Brian
 
Please everyone - wire them to the standard regardless if the random pinout did work. Then you'll know they are to spec and can be used for anything in the future.
 
Just thought I would pop in something I found - I got lazy and used one of my old cables to connect an E1.31 controller. Started alright but as the 30 second test sequence kept looping the lights started weird strobing that got worse until you couldn't see the actual sequence it was just strobing. So I crimped a new cat5 cable using T-568B and in the short test I could run this morning no problems.
In short, it does make a difference for E1.31. As Driver suggests, it's a good habit to crimp a standard cable.
 
Each pair in Cat cabling as a differnt twist per foot rating, so by using the wrong pairs, it may have introduced some more unexpected interference into the signal.
 
I think in this case it was because Ingrid had simply arranged the pairs from left to right, not in the middle, next to middle and outer pairings. That would result in split pairs which really plays havoc with Ethernet.
 
Great that you ended up going back to the standard Ingrid, and I'm not really surprised that it did not work, if it was a long run, although I expected the odd flicker not as you described.
 
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