# Building DMX Cables



## JoeML (May 17, 2011)

So I just bought 27 NC3(M/F)XX ends with all the color boots for fast set up of my light shows. I'm currently using 12 Martin Mac 500's.

I looked everywhere online, and nobody had a answer for this question, which I will ask here first.

Can I use DMX5 cable in a DMX3 connector? 

The reason for this question is simple in my mind. If I want to upgrade my connectors to DMX5, I already have the wire. Or if I have a bad wire in the cable using DMX3, I can use 1 of the 2 wires that aren't being used. Its a bulkier cable, hopefully more durable.

But at the same time, I've read DMX5 is rarely used. So why do we even have it, except for some high end system stuff. I'm thinking about getting some ETC Desire fixtures in the future, that use the DMX5.

And I still don't have the cables yet, but there is some good stuff around. I HATE the idea of having anything the ADJ in my inventory, but there cable seems to be good, from what I've read. I'd really like to know the brand name of cable that HOSA uses! But I haven't found that either. I think its dura-flex or something. 

Looking for very good DMX cable in a 500' length spool. But not over $350

Simple answers would be helpful even with ballpark figures


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## mstaylor (May 17, 2011)

Yes, you can use 5 wire in a 3 wire XLR.


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## DuckJordan (May 17, 2011)

First things first check out the search function on the forum as the topic of 3 pin vs 5 pin XLR connectors for DMX use has been covered far too many times. as long as it has 120 ohm data rated cable you can use it.


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## JD (May 17, 2011)

Current DMX 512 protocol is to use two pair cable. The first pair is connected to pins 2 and 3, the second pair is connected to pins 4 and 5. The shield is connected to pin 1. 

That being said, I can't think of any equipment that is actually using the pair connected to pins 4 and 5! It just never came to be.

The wiring for the 3 pin and 5 pin XLRs is the same for the first 3 pins. No point in using cable that has a second pair, unless you want to do something non-standard (like some of us do) and use the second pair for a second universe or a com line. 

When buying the wire, it is fine to use 3 conductor wire (single pair and a shield), just make sure the wire is rated for DMX usage and isn't mic cable. Although people use mic cable all the time, it is a different impedance and may cause problems. Or, as some say, "it will work great until someday it doesn't."

EDIT: as noted above, there are many, many threads on this forum on the topic of cable and connectors, and the need to terminate at the end of the run.


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## mstaylor (May 17, 2011)

He is looking more for cable recommendations than how to convert. This is something I don't generally buy in bulk form so I had no information for him.


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## DuckJordan (May 17, 2011)

JD said:


> Current DMX 512 protocol is to use two pair cable. The first pair is connected to pins 2 and 3, the second pair is connected to pins 4 and 5. The shield is connected to pin 1.
> 
> That being said, I can't think of any equipment that is actually using the pair connected to pins 4 and 5! It just never came to be.
> 
> ...



Actually, it is used, Quite frequently but more for video networks than our standard theater setups. The second set is for fixtures to talk back to the console. DMX out to fixture then the fixture sends info back to the console it helps when dealing with trouble shooting large moving light rigs that are in the air just how ACN is currently working towards. Its for letting the lights tell you, Hey, I have a bad lamp, or something is wrong with my motor for the gobo rotation, or other things that sensors in the movers would be able to pick up.


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## JD (May 17, 2011)

DuckJordan said:


> Actually, it is used, Quite frequently but more for video networks than our standard theater setups. The second set is for fixtures to talk back to the console. DMX out to fixture then the fixture sends info back to the console it helps when dealing with trouble shooting large moving light rigs that are in the air just how ACN is currently working towards. Its for letting the lights tell you, Hey, I have a bad lamp, or something is wrong with my motor for the gobo rotation, or other things that sensors in the movers would be able to pick up.



That's what it is designed for, but in the lighting world, what fixtures are currently using that feature? (Factory units)


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## JoeML (May 17, 2011)

Ok, So I can use the cable in a DMX3 connector!

But on the wire, If i were to buy lets say 110 ohm wire, would i need to make a 110 ohm terminator to match the wires impedance? Or will my 120 ohm still do?

And should I worry about Capacitance Ratings, Single or Double Shields,Twisted pairs or 4 wires twisted together inside of shield, meets USITT standards, Temperature limits and a drain wire vs shield?


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## JoeML (May 17, 2011)

@JD
I think that's what the ETC Desire fixture is doing, but not sure. I think you can change the settings on the fixture from your console! If I read it correctly


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## mstaylor (May 17, 2011)

You need to buy cable that meets the DMX spec. You can do it with noncompliant cable and it will work until it doesn't. I am assuming you are making three pin cables because your DMX toys all have three pin. That's fine just make sure you follow the pinout and use proper cables. Also make some terminators.


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## derekleffew (May 17, 2011)

JoeML said:


> ...Can I use DMX5 cable in a DMX3 connector? ...


First, there's no such thing as "DMX5 cable" or "DMX3 connector." But hopefully you knew that, so we'll move on. 
This summer will be the 25th anniversary of the ratification of USITT DMX512-1986. In my opinion/estimation/speculation, If the geniuses behind the CPWG haven't come to agreement on the use of the 2nd pair by now, they never will. They've mostly moved on to RDM and ACN, and are unlikely to revisit or revise significantly DMX512. Save the money and buy single-pair+shield cable. If you do use 2pr+shld cable with XLR3 connectors, care must be taken to heat-shrink or otherwise isolate the unused wires inside the XLR shell. Don't just cut them flush so they can eventually short to something.


JoeML said:


> ...Looking for very good DMX cable in a 500' length spool. But not over $350...


So ≤ 70¢ a foot? Any data-grade, RS-485 recommended, 110-120Ω 22-24g single pair+braided shield will work fine for DMX. Search for Belden 9841 or equivalents by WestPenn, Alpha, or Gepco. If you feel you must have 2pr.+shield, do a price search for Gepco DLC224.



DuckJordan said:


> Actually, it is used, Quite frequently but more for video networks than our standard theater setups. The second set is for fixtures to talk back to the console. DMX out to fixture then the fixture sends info back to the console it helps when dealing with trouble shooting large moving light rigs that are in the air just how ACN is currently working towards. Its for letting the lights tell you, Hey, I have a bad lamp, or something is wrong with my motor for the gobo rotation, or other things that sensors in the movers would be able to pick up.


Sorry, incorrect. I challenge you to cite *any* fixture, console, or device that utilizes the second pair for fixture talkback, or anything else for that matter. See also this post . (The thread contains some valid and invalid uses, which are ineligible for this challenge.)


JoeML said:


> ...I think that's what the ETC Desire fixture is doing, but not sure. I think you can change the settings on the fixture from your console! If I read it correctly


You read correctly. With the Desire and appropriate ETC RDM-equipped console. But it doesn't use pins 4&5 to do that. RDM operates over pins 1,2,3, simultaneously with the DMX signal.


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## JoeML (May 17, 2011)

I plan to redo my terminator with the new connector, to keep it clean looking. I know about the need of terms, and all that DJ cheap BS, which I do stay away from. ~Once you go pro, that's the way to go!~

I'm just wanting to have a new clean, professional looking area for my wire runs, connections and fixtures.


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## rochem (May 17, 2011)

JD said:


> That's what it is designed for, but in the lighting world, what fixtures are currently using that feature? (Factory units)


 
More than you'd expect, actually. More and more products are being rolled out that are "RDM-ready", the problem is that people just aren't using it! The one that immediately comes to mind is Wybron. They've had a proprietary talkback system in place for their scrollers for quite some time - this is why you could check the status of your scrollers from the PSU. With the new Coloram IT family, this talkback functionality is integrated with RDM protocol, allowing you to receive feedback and even address the scrollers via RDM. A friend of mine is the house electrician at a theatre in Texas that just got a major upgrade, and they use their Eos to talk to their Coloram ITs*. I can't remember many more off the top of my head, but I have a rental package that includes Mac IIIs in the air right now, and those are also RDM-enabled (though I have yet to actually try to use it... perhaps that's a project for this week...).


*I know they have RDM enabled between the Eos and the ITs, but I'm not sure what functions they actually use it for.


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## JoeML (May 17, 2011)

derekleffew said:


> First, there's no such thing as "DMX5 cable" or "DMX3 connector." But hopefully you knew that, so we'll move on.


Yes, didn't know if this was more of a high school forum


derekleffew said:


> So ≤ 70¢ a foot? Any data-grade, RS-485 recommended, 110-120Ω 22-24g single pair+braided shield will work fine for DMX. Search for Belden 9841 or equivalents by WestPenn, Alpha, or Gepco. If you feel you must have 2pr.+shield, do a price search for Gepco DLC224.


will this still be the black & round or grey and looks like a cat5 cable?


derekleffew said:


> You read correctly. With the Desire and appropriate ETC RDM-equipped console. But it doesn't use pins 4&5 to do that. RDM operates over pins 1,2,3.


Didn't see any other connector, so I just thought. But thanks for informing me!


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## derekleffew (May 17, 2011)

JoeML said:


> Will this [Belden 9841] still be the black & round or grey and looks like a cat5 cable?


Got me there. 9841 is round, but only comes in gray. For your purposes, since you can't afford/don't need the Rolls-Royce, indestructible ProPlex, I've heard Accu-Cable is actually not bad. Seems to be priced right, at ~35¢/ft.

BTW, MAC 500's came new from Martin with a 5m data cable included. It was quite thin, and used an odd style of XLR3 connector, but I never had a problem with any of those cables, for several years and fairly hard usage.

There's also this thread: http://www.controlbooth.com/forums/lighting-electrics/15407-facts-about-dmx.html , which you might find amusing. Not helpful, I realize, but amusing nonetheless.

To answer another of your questions, there's no appreciable difference between 110Ω and 120Ω cable. A 120Ω terminator, DMX will work fine with either.


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## JD (May 17, 2011)

rochem said:


> More than you'd expect, actually. More and more products are being rolled out that are "RDM-ready", the problem is that people just aren't using it! The one that immediately comes to mind is Wybron. They've had a proprietary talkback system in place for their scrollers for quite some time - this is why you could check the status of your scrollers from the PSU. With the new Coloram IT family, this talkback functionality is integrated with RDM protocol, allowing you to receive feedback and even address the scrollers via RDM. A friend of mine is the house electrician at a theatre in Texas that just got a major upgrade, and they use their Eos to talk to their Coloram ITs*. I can't remember many more off the top of my head, but I have a rental package that includes Mac IIIs in the air right now, and those are also RDM-enabled (though I have yet to actually try to use it... perhaps that's a project for this week...).



But once again, RDM runs overlaid on the first pair (2 and 3) so 4 and 5 remain unused.


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## DuckJordan (May 17, 2011)

I bow to derek's vast knowledge and retract my previous statement. I wasn't remembering them correctly.


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## len (May 17, 2011)

JoeML said:


> But at the same time, I've read DMX5 is rarely used. So why do we even have it, except for some high end system stuff. I'm thinking about getting some ETC Desire fixtures in the future, that use the DMX5.



On a side note, this isn't really true. Most of the top end units are all 5-pin. A lot of fixtures have both 3-pin and 5-pin connectors because the end customers are requesting both and it's just cheaper to make one unit with both than to stock 2 different products with such a minor difference. As long as all the parts of the cable are dmx-compliant (except for the 3-pin part) and can accurately carry signal, it doesn't really matter. Personally, I think it makes sense to ONLY use 5-pin for dmx, 4-pin for scrollers, and let audio have 3-pin. There would be far less confusion over which cable belongs where. But the marketplace has dictated otherwise.


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## starksk (May 18, 2011)

derekleffew said:


> ... With the Desire and appropriate ETC RDM-equipped console. But it doesn't use pins 4&5 to do that. RDM operates over pins 1,2,3, simultaneously with the DMX signal.



Derek is correct here. Desire has a 5-Pin XLR connector to be compliant with the DMX standard, but pins 4 & 5 are unused by the fixture and just pass from the input connector to the output connector to allow those (rare) devices that may be using those pins to continue getting the signal.


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## derekleffew (May 18, 2011)

starksk said:


> ...to allow those (rare) devices that may be using those pins to continue getting the signal.


...to allow those [-](rare)[/-] (non-existent) devices... 

Two of the biggest headaches/controversies/frustrations in lighting during the past thirty years:

3pin vs. 5pin
Reverse Ground and Neutral or not
and Mr. STEVETERRY had a hand in both of them. Hmmm.


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## church (May 18, 2011)

just a practical comment re the use of 5 wire cable with XLR connectors. Check the cable with the connectors. The cable diameter varies and XLRs from different manufacturers will not accept all cables soldfor DMX. I have found that Neutrik connectors accept the larger diameter cables.


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## JD (May 18, 2011)

Odd thing is that some of the better "2 pair" cable is actually not 2 pair, but one big twisted quad! If you are only using it for standard DMX, it does not really matter. However, if you intent to do some of that non-compliant stuff, like send a second universe down the other pair, you want to inspect a sample of the cable and see that there truly are two separate 2 wire pairs. Ideally, I like to see separate shields around each pair, but that's just me! The fact that DMX works great using CAT5 cable (in non-flex applications) which is not shielded at all, proves that is not a requirement. 

Whatever you do, suppress the urge to use the second pair to double up the conductors on pins 2 & 3. My own take is to solder all unused conductors to pin one as that leaves no "strays" that may bite you later. The other alternative is to cap the unused wires with heat-shrink like Derek said.


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## millamber (May 18, 2011)

derekleffew said:


> I challenge you to cite any fixture, console, or device that utilizes the second pair for fixture talkback, or anything else for that matter.



As I remember it, early Vari*Lite 2c's and VL4's used pins 4 and 5 to transmit firmware code between fixtures for software upgrades.


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## derekleffew (May 18, 2011)

millamber said:


> As I remember it, early Vari*Lite 2c's and VL4's used pins 4 and 5 to transmit firmware code between fixtures for software upgrades.


It _may_ have been pins 4&5, but it wasn't an XLR5 (IIRC they used an 9pin CPC connector, aka "SuperLamp cable") nor DMX512 (Series 200 fixtures could not listen to DMX without a DMX200).

> *Series 200 Components*
> VARI❋LITE® Series 200™ luminaires can be controlled with DMX512 protocol using a DMX200
> interface unit. The DMX200 interface converts DMX512 protocol to Series 200 comm in order to
> control these luminaires. The Series 200 ACS rack provides power to Series 200 luminaires through
> ...


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## xander (May 18, 2011)

JD said:


> The fact that DMX works great using CAT5 cable (in non-flex applications) which is not shielded at all, proves that is not a requirement.


I thought that the conduit that is required when using category cable for DMX512 acted as the shield, hence making it allowed by the standard. 

-Tim


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## derekleffew (May 18, 2011)

From the pdf cited here:

> In a series of independent laboratory tests conducted
> for ESTA’s DMX-over- Category 5 Cable Task Group,
> cat 5 was found to be as suitable for DMX512 data
> transmission as the recommended standard DMX512
> ...



and from KnowledgeBase: DMX Over CAT 5 - Electronic Theatre Controls :

> Suggested Wiring Practices
> 
> Do not run data signals next to or in the same conduit as high power sources. If necessary to be near these sources cross over them at 90 degrees or keep as much parallel distance between them as possible.
> Use IDCs for all Category 5 cable applications.
> ...


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## JoeML (May 18, 2011)

Ok, so I could either get the Accu-Cable @ $104/300', Gepco DS601<- Not listed as DMX @ $95 or maybe the MAXPRO DMX500MP @ $100 stuff.

So im thinking any DMX cable with shield and twisted are the same, like an a HDMI cable. You can buy the cheapest or the most expensive name brand, but still get the same results.

And thanks for all the help!


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## DuckJordan (May 18, 2011)

JoeML said:


> Ok, so I could either get the Accu-Cable @ $104/300', Gepco DS601<- Not listed as DMX @ $95 or maybe the MAXPRO DMX500MP @ $100 stuff.
> 
> So im thinking any DMX cable with shield and twisted are the same, like an a HDMI cable. You can buy the cheapest or the most expensive name brand, but still get the same results.
> 
> And thanks for all the help!


 
Kind of, Although I have noticed with the cheaper cable that it isn't nearly as durable as some others. I've found that over time as wrapping and unwrapping and just overall use will slowly deteriorate the individual wires as well as the outer jacket.


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## JoeML (May 18, 2011)

Ok, i guess i did think about that part of it. Good call!

I hope your overall time frame is at least 5 years? Cause my current cables have lasted almost 10 years now! Although I do keep them out of way. Put carpet over them instead of tape in walkways, or run them along the walls and clean them with water when muddy.


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## derekleffew (May 18, 2011)

Avoid the Gepco DS601. 26g is too small (not for current, but for mechanical strength, purposes), and you want a braided, not foil, shield for durability.


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## DuckJordan (May 18, 2011)

JoeML said:


> Ok, i guess i did think about that part of it. Good call!
> 
> I hope your overall time frame is at least 5 years? Cause my current cables have lasted almost 10 years now! Although I do keep them out of way. Put carpet over them instead of tape in walkways, or run them along the walls and clean them with water when muddy.


 

actually the cables that broke or caused problems cause issues in 2 years and was from only about 20 uses, This was at a local College and were the last to be put in first to be pulled out kind of thing. So very, very careful with the cables.


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## tdrga (May 23, 2011)

derekleffew said:


> Sorry, incorrect. I challenge you to cite *any* fixture, console, or device that utilizes the second pair for fixture talkback, or anything else for that matter.


 
Rosco/ET IPS dimmer bars and packs use pins 4/5 for talkback. One of the very few actual useful and compliant uses of pins 4/5.

They are no longer made by Rosco and ET doesn't exist anymore- I'm not sure if the current Philips/Strand S21 products that are descended from the IPS line still use pins 4/5.

-Todd


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## icewolf08 (May 23, 2011)

tdrga said:


> Rosco/ET IPS dimmer bars and packs use pins 4/5 for talkback. One of the very few actual useful and compliant uses of pins 4/5.
> 
> They are no longer made by Rosco and ET doesn't exist anymore- I'm not sure if the current Philips/Strand S21 products that are descended from the IPS line still use pins 4/5.
> 
> -Todd



Technically, there are no "compliant" uses for pins 4 and 5 according the the DMX standard. They were reserved for future use and that future use was never actually specified. So, technically, any use of pins 4 and 5 is not compliant with the DMX standard, much the same as using an XLR-3 connector is not compliant..


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## tdrga (May 24, 2011)

icewolf08 said:


> Technically, there are no "compliant" uses for pins 4 and 5 according the the DMX standard. They were reserved for future use and that future use was never actually specified. So, technically, any use of pins 4 and 5 is not compliant with the DMX standard, much the same as using an XLR-3 connector is not compliant..


 
Actually, the language in the ASNI E1.11 2004 document refers to the secondary data link as "optional"- and it is specified as another EIA-485-A data link. From Annex B of the standard:"The original and 1990 versions of USITT DMX512 called out an “Optional Second Data Link.” There was no detailed guidance for it use. The majority of legacy systems did not use the second data link at all. Many uses of the second data link have been implemented over the years. While many of these were reasonable, a few uses clearly were not compliant with EIA-485-A. These uses vary in both their electrical requirements and in the data protocol used. One of the purposes of this standard is to regularize the use of the second data link . It is no longer possible to select a single implementation and forbid all others. However, not all historical uses will be allowed to continue."​Earlier versions of the DMX standard did not deal with pins 4/5 and left them as "reserved" but the current DMX-A standard does specify that they must be a data link. So the Rosco/ET products are compliant with the current standard (even if by chance, since they were designed before the DMX-A standard existed).

-Todd


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## derekleffew (May 25, 2011)

tdrga said:


> ...They are no longer made by Rosco *and ET doesn't exist anymore* ...


They don't? Entertainment Technology


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## avkid (May 26, 2011)

derekleffew said:


> They don't? Entertainment Technology


 
They better, I love me some Bak Pak dimmers!


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## tdrga (May 26, 2011)

derekleffew said:


> They don't? Entertainment Technology


 
Well, I stand corrected- I didn't realize that ET remained as a distinct division within Philips.

-Todd


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## derekleffew (May 27, 2011)

avkid said:


> They better, I love me some Bak Pak dimmers!


I've asked this before and not received a satisfactory response: 
What's the difference between an ET Bak Pak and a Strand Light Pack?


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## dramatech (May 27, 2011)

derekleffew said:


> I've asked this before and not received a satisfactory response:
> What's the difference between an ET Bak Pak and a Strand Light Pack?



I don't know if this is the answer that you are looking for, but a few months back, I purchased a Strand Light Pack on ebay. I did so because the price was to good to pass, and it looked just like the ET Bak Pak, and I also wanted to get my first IGBT dimmer. I pulled an adhesive label from the unit, and underneath it is a ET Bak Pak.

Tom Johnson


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