Monoprice DMX Cable wiring

cvhstech

cvhstech

Member
Monoprice doesn't say what color the interior wires are, but hopefully:

Pin-out:
1-- Ground ; shield (the braid)
2-- Data- ; black wire
3-- Data+ ; white wire
4-- Data2- ; green wire (might be blue instead)
5-- Data2+ ; red wire (might be orange)

Looking at solder side of female XLR-5:
proxy.php


OR, http://www.controlbooth.com/threads/dmx-wiring.12060/#post-127260 (the opposite). Most important is to make the same color go to the same pin# on each end, AND, in the future, OPEN BOTH ENDS of any cable you are repairing or trouble-shooting.
 
Make sure one twisted pair connects to pins 2 and 3, and the other twisted pair to 4 and 5.

[ Corrected to fix an obvious brain fart...]

/mike
 
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n1ist said:
Make sure one twisted pair connects to pins 1 and 2, and the other twisted pair to 4 and 5.
/mike
Click to expand...

Um, actually it should be shield on 1, a twisted pair on 2 and 3 and the other twisted pair on 4 and 5.

David
 
n1ist said:
Make sure one twisted pair connects to pins 2 and 3, and the other twisted pair to 4 and 5. ...
Click to expand...
(I'll bring this up before @JD does; see here.) We've no guarantee that the cable in question actually consists of two twisted pairs, but rather is four wires all twisted together. Since it's unlikely that signal will ever be sent down wires 4&5 (unless we're using ET's IPS devices, or "unauthorised" universe-saver adapters), it really doesn't matter, does it?
 
derekleffew said:
(I'll bring this up before @JD does.) We've no guarantee that the cable in question actually consists of two twisted pairs, but rather is four wires all twisted together. Since it's unlikely that signal will ever be sent down wires 4&5 (unless we're using ET's IPS devices, or "unauthorised" universe-saver adapters), it really doesn't matter, does it?
Click to expand...


Even though there is no use on those pins for USITT DMX, Soldering 2 extra connections shouldn't be too difficult or take much extra time. If you have those connections, you could make an adapter that would allow you to use one DMX cable to carry 2 universes and then split off on the other end so you could use all 4 conductors.

If you are only using 3 pin XLR, then you can't solder the pins so it doesn't matter. But if you are using 5 pin, what does it hurt?
 
ANSI spec says that the second cable pair (4+5) can be used for lots of stuff but does specifically prohibit the transport of a second universe with them.
 
Well yeah. A conductor is a conductor. You could also use rusty air craft cable or barbed wire. Doesn't mean its a good idea. And when cat 5 cable is so cheap why not just build spec cables.

Edit: word choice
 
TuckerD said:
Well yeah. A conductor is a conductor. You could also use rusty air craft cable or barbed wire. Doesn't mean its a good idea. And when cat 5 cable is so cheap why not just build spec cables.
Click to expand...
Each break-in or break-out for two universes on one cable would require 3 connectors - plus the 2 connectors on the run for a total of 8 connectors vs. 4 connectors (two on each cable). So assuming that you're building your own cables and neglecting the extra labor of attaching more connectors the cost of the cable would have to be at least twice the cost of the connectors before it would pay off to make these non-standard break-in/break-out adaptors.
 
robartsd said:
Each break-in or break-out for two universes on one cable would require 3 connectors - plus the 2 connectors on the run for a total of 8 connectors vs. 4 connectors (two on each cable). So assuming that you're building your own cables and neglecting the extra labor of attaching more connectors the cost of the cable would have to be at least twice the cost of the connectors before it would pay off to make these non-standard break-in/break-out adaptors.
Click to expand...
I'm not the one propossing such an idea. I am in fact against it. In the post you quote I say "cat 5 is so cheap just build spec cables".
 
What does cat 5 cable being cheap have to do with building DMX cables to spec? I realize we're pretty far into the minutia here, but still...
 
I just built and used such breakouts on my last dance show. That let me use the second pair of an installed run of DMX (the primary pair ran the house dimmer) rather than having to pull my own cable from the stage to the booth. It was a big time savings when I only have two hours for loadin, setup, and focus... I have also used one to pull two audio lines over an installed DMX.

/mike
 
That wouldn't shock me but that still doesn't mean doing so is in line with spec.

epimetheus said:
What does cat 5 cable being cheap have to do with building DMX cables to spec? I realize we're pretty far into the minutia here, but still...
Click to expand...

Cat 5 is recognized by the spec as cable that can be used for building dmx cables. It is also really cheap. The spec recommends doing so for permanent or semi permanent runs. My opinion on the matter is that its cheap so of you use it on a non permanent run and you lose the cable to wear and tear it's no bibig deal. If I was a touring show I wouldn't be using it because I wouldn't have time to replace it.

@n1ist interesting scenario. That's one of the arguments I have a hard time debating. When you're on the road or in another house you have to get the show on. I don't know enough about audio line levels to feel one way or the other about your final comment. I wouldn't make that choice because of my lack of knowledge.
 
Cat 5 has the same resistance as the RS485 spec for DMX correct? So as long as matching twisted pairs are used, you could use that cable to carry 4 universes on one Cat 5 cable? And since the twists matter more than the shielding (especially if it is alone in EMT conduit), then that would be possible.

Am I correct in all of this?

I am not saying that coming up with your own adapters and changes is in agreement with the standard, but rather that there are modifications that, if done correctly, could make things cheaper/more flexible/adaptable.
 
One cat5 cable has 8 conductors as four twisted pairs. The data connection requires a ground which can be shared by multiple data connections. So one cat 5 cable could support 3 universes. ENTTEC has a product for this that they presented at USITT 2014 but I couldn't find it online.

Like you said though, not spec. Just a modification that could be a convenience if you can't manage to run more than one cable or a modern network like Net3/ACN.

I seem to have managed to high jack another thread into a standards talk. Sorry @cvhstech If this conversation is to continue it might be good to do it someplace else.
 
CanYouHearMeNow said:
Cat 5 has the same resistance as the RS485 spec for DMX correct? So as long as matching twisted pairs are used, you could use that cable to carry 4 universes on one Cat 5 cable? And since the twists matter more than the shielding (especially if it is alone in EMT conduit), then that would be possible.

Am I correct in all of this? ...
Click to expand...
A well-respected manufacturer appears to agree with you:
from: http://www.tmb.com/products/82-sneak-snake :
DMX over CAT5e Snake System
Carry multiple DMX512 universes over a single CAT5e cable!
proxy.php

- Available in 2-, 3-, and 4-universe versions. All utilize the same ProPlex CAT5e cable.
Click to expand...
FYI, it's impedance and capacitance that matter more than resistance.

Another well-respected manufacturer USED TO offer XLR5 break-in / break-out "Universe Saver" adaptors enabling two universes down one 5pin cable, but the item has disappeared from its website. Perhaps the DMX police got to them?

EDIT: Lex Products responded thusly:
We hardly ever see anyone that needs this anymore. Demand dropped to less than one inquiry a year, therefore we removed it from the website and price list to free up space.

We do still have the drawings and we can still make it using the old PN# DMXUSS. Only a few of the sales reps here will still remember it, but trust me...it's a thing.

While the ANSI standard doesn't support it, as @CanYouHearMeNow said, the cable and connectors will physically support the splitting operation. We don't make cables that are against the NEC because someone can get injured (like the Male-Male Edison I was asked about the other day, then screamed at and asked why we don't build it). But DMX cables, we do frequently make adapters because people usually have developed their own protocols, or use for them, and there is no code or standard that has to be strictly adhered to, like the NEC is for power. We do therefore make this, as well as strange 6-pin to 5-pin XLR adapters, 3-pin to RJ45 with odd pinouts, and other weird ones.
Click to expand...
-----
TuckerD said:
... I seem to have managed to high jack another thread into a standards talk. Sorry @cvhstech If this conversation is to continue it might be good to do it someplace else.
Click to expand...
It's not you, it's me. Control Booth management doesn't mind too much veering off/hi-jacking (some of our best conversations started that way) provided:
The original question asked has been answered, and
Discussion remains somewhat relevant, however loosely.
 
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