Can or should I not do this with a dmx cable.

Crisp image

Well-Known Member
I know I can but should or could I do this with a dmx cable.
The cable in question runs from the bio box to side stage. It is a 5 core shielded cable that currently delivers dmx to the stage.
Seeing as dmx only uses 3 cores (d- d+ gnd) will using a common ground and the other 2 cores to send a second universe to side stage be a problem. I seem to recall that the 5 pin dmx was designed to do just this but never took off.
This will give a little more flexibility at a low price point.
Regards
Geoff
 
I know I can but should or could I do this with a dmx cable.
The cable in question runs from the bio box to side stage. It is a 5 core shielded cable that currently delivers dmx to the stage.
Seeing as dmx only uses 3 cores (d- d+ gnd) will using a common ground and the other 2 cores to send a second universe to side stage be a problem. I seem to recall that the 5 pin dmx was designed to do just this but never took off.
This will give a little more flexibility at a low price point.
Regards
Geoff
@Crisp image Let's summon: @STEVETERRY and / or @jfleenor for a definitive answer. . .
Toodleoo!
Ron Hebbard
 
If the cable truly has two independent twisted pairs, then yes, it would work. I do that myself. HOWEVER, I have seen a lot of DMX cable that has four wires twisted together in a "twisted quad", so to speak. That would not work.
Example of "Twisted Quad":
SOM540-0051.jpg
 
So we are talking about maybe a 20m run?

Everything I have experienced about RS485 says this will be easily accomplished. In the real world most RS485 just gets carried on telephone wiring.

(Everything I read on lighting forums says the DMX gods will smite you for even asking.)
 
If the cable truly has two independent twisted pairs, then yes, it would work. I do that myself. HOWEVER, I have seen a lot of DMX cable that has four wires twisted together in a "twisted quad", so to speak. That would not work.
Example of "Twisted Quad":
View attachment 18342
I will have a close look and decide what it is.

So we are talking about maybe a 20m run?
Rough guess 35 to 40m if you measure the drop to the connection points
 
I understand the standard has-been updated to officially allow dual universes.

There are many cautions about all the incompatible other uses for the second pair. But those are pretty rare these days.
 
Sure, a piece of ZIP cord and a couple of chuncks of hookup wire will probably carry your two universes--until they don't. A few hundred feet of the proper spec cable will cost FAR less than proper installation of same. Follow the proper spec and do it once and stop worrying about it.
 
Sure, a piece of ZIP cord and a couple of chuncks of hookup wire will probably carry your two universes--until they don't. A few hundred feet of the proper spec cable will cost FAR less than proper installation of same. Follow the proper spec and do it once and stop worrying about it.
This particular cable is already in the wall so hence my question. If I was doing a new install it would on separate cables for sure.
 
Depends on the cable. Goldmine would be if it were Cat5/Cat6 in conduit, which actually can handle 3 universes even though it is the cheapest.
It all hinges on how the wires are paired.
 
Belden 8723 is not even close to the correct impedance for DMX, which may cause data errors. There is nothing wrong with using two pair DMX cable, and having a few inches of twisted pair un-shielded in tight shrink tubing. Maintaining uniform pair twist accomplishes most of the noise immunity.
 
Belden 8723 is 52 ohms. You want something that is 110 to 120 ohms. Twisted pairs is the other important characteristic. That's why (ironically) cheap Cat6 is great (110 ohm) although not for portable applications as most is solid conductor.
 
Stick with the cat 5 or cat6 six as mentioned above
it is now an acceptable cable and works great
and as was mentioned you cab get (3) universes
there are several companies who make panel mount XLR's with terminal strips
no need to solder.
you can even use the stranded cat5 5 that is used for RJ45 cables to make patch cords and cables
 

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