good pre-made dmx cable
- Thread starterJeffhtg
- Start date
Look up the specs for Belden 9842, accepted by many/most as the defacto industry standard.
Or Belden 9729 (or equivalent, as specified by ETC). Also, see attached: View attachment Belden_DMX-512.pdf
Depends on the intended use. In conduit or out? Plenum or non-plenum? Next to hot lights? As an FOH snake?
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STEVETERRY
Well-Known Member
If you cut your cable apart, it better have TWO SEPARATE PAIRS or it really isn't DMX512.
I know there is a ton of what is called "excellent" DMX cable out there that is actually four conductors twisted together with one overall shield. In the computer world, we would call that "dumpster fill." Lucky for the manufacturer, DMX is a hearty signal that is unidirectional, and in most cases only two of the conductors are used. The cable works fine. But....... IT'S NOT DMX! (Despite what is printed on the rubber!)
Proper Construction: West Penn Wire Permanent Installation Bulk Cable
The E1.11 standard does not require a separate shield for each pair. There would be no advantage to a separate shield.
ST
JD
Well-Known Member
I know what you're saying, but it doesn't make it right! Cable manufacturers, even Belden, have been getting away with murder! No surprise. Two data lines = Two individual twisted pairs, not four conductors twisted together!
STEVETERRY
Well-Known Member
JD
Well-Known Member
Yes, agreed, although I would not use it. My own opinion. But, my original statement was:
"I know there is a ton of what is called "excellent" DMX cable out there that is actually four conductors twisted together with one overall shield."
There are several major vendor that are selling DMX that is indeed four wires twisted together as one pair.
STEVETERRY
Well-Known Member
JD--
I did not know that. It would be helpful if we could identify those vendors and part numbers to warn consumers ways from such a design of cable--which is clearly bogus for DMX-512 applications and will not work reliably.
EIA-485 has a twisted pair requirement. Not four wires twisted together, unless they are two twisted pairs, twisted together, which would be fine for DMX512.
ST
JD
Well-Known Member
I recall this discussion from about 6 months back on this site, but I do not remember the thread title. Derek was part of the discussion so he may recall it. In buying bulk cable it is always good to get a sample first.
EDIT:
Wow, maybe more like two years ago! See post # 19:
http://www.controlbooth.com/forums/lighting-electrics/18596-dmx-help-wire-colors.html#post170713
Some quick questionable Google finds:
http://www.chinesedepartmentstore.com.cn/osc/product_info.php/products_id/6595
http://www.cmpstore.com/DMX-4C-22GAShield-BlackCable-by-the-foot-CA-DMX4C.htm
EDIT:
Wow, maybe more like two years ago! See post # 19:
http://www.controlbooth.com/forums/lighting-electrics/18596-dmx-help-wire-colors.html#post170713
Some quick questionable Google finds:
http://www.chinesedepartmentstore.com.cn/osc/product_info.php/products_id/6595
http://www.cmpstore.com/DMX-4C-22GAShield-BlackCable-by-the-foot-CA-DMX4C.htm
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Yes, JD, but I am in agreement with post #20 of the same thread:
Furthermore,
Sorry for the confusion in posts 17-29 above. We're discussing at least three types of cable constructions:
In most cases. IF I were building my own fixture jumpers, I'd use an appropriate (100-120Ω, 20-22g, heavy Black jacket, braided shield, but still flexible/coilable, ...) single pair + shield cable.
And even though this has little/nothing relevant, I did update the wiki entry star quad.
Unless/until there's widespread adoption and agreement as to the use of the second pair (which there never will be, as the standard is nearing the end of its lifecycle), I'm not going to worry about it.
Furthermore,
-----
Sorry for the confusion in posts 17-29 above. We're discussing at least three types of cable constructions:
- 4 conductor + shield
- 2 pair, individually twisted, + 1 overall shield
- 2 individually, twisted, shielded pairs (2 shields)
In most cases. IF I were building my own fixture jumpers, I'd use an appropriate (100-120Ω, 20-22g, heavy Black jacket, braided shield, but still flexible/coilable, ...) single pair + shield cable.
And even though this has little/nothing relevant, I did update the wiki entry star quad.
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JD
Well-Known Member
Just came across this great video from Doug Fleenor on 1 pair vs 2 pair, 5 pin vs 3 pin, and when cat5 is ok to use. He also covers length limits and some other things.
He makes the case for two pair use in large production houses and then ... Surprise! Indicates his own opinion is that it is a waste of money. Pretty funny video from Dr. DMX!
Informational Video: DMX512 Cable - Part Two - YouTube
Well, as I said earlier: "DMX is a hearty signal that is unidirectional, and in most cases only two of the conductors are used. The cable works fine."
but.... Then there are some of us that like to pop a second universe on the second pair, or even a com line....
Oh! what a tangled web we weave!
He makes the case for two pair use in large production houses and then ... Surprise! Indicates his own opinion is that it is a waste of money. Pretty funny video from Dr. DMX!
Informational Video: DMX512 Cable - Part Two - YouTube
Well, as I said earlier: "DMX is a hearty signal that is unidirectional, and in most cases only two of the conductors are used. The cable works fine."
but.... Then there are some of us that like to pop a second universe on the second pair, or even a com line....
Oh! what a tangled web we weave!
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Belden 9841, but I don't like that it's only 24 ga. (not for capacity, but for durability) for portable use. I'd look for a cable for EIA RS-485 application with all of the criteria above: "(100-120Ω, 20-22g, heavy Black jacket, braided shield, but still flexible/coilable, ...) single pair + shield cable."
Or, just bite the bullet and buy TMB ProPlex PC244T.
"The bitterness of poor quality remains long after the sweetness of a low price is forgotten." --Benjamin Franklin
So I really don't care about the opinions here.. 4 pair twisted vs 2 pair pairs twisted... all i'm really looking for is good quality inexpensive 3 pin dmx cable. back to topic - does anyone have any leads?
Best I've found is custom made by Bill at Entertainment Systems. About the same price as pre-made stuff, but it comes in whatever length you need. I think he offers a lifetime replacement guarantee on it, but check with him.
Every one he made for me is still perfect.
I've also bot American DJ stuff, and for the price it's fine. Cheap enough to be disposable.
Every one he made for me is still perfect.
I've also bot American DJ stuff, and for the price it's fine. Cheap enough to be disposable.
Well Jeff, all I could think of is there's really no such thing as "3 pin DMX cable" but if you actually paid attention to some of the posts by some of top people in the industry, you'd know that.
Sorry to have wasted your time and as BTW, welcome to Control Booth.
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It's simple then. No cable for you.
As many others have said there is no such thing as "good quality inexpensive 3 pin DMX."
You have inexpensive DMX, good quality DMX, and XLR3 terminated data cable which does not fit under any standards and is NOT DMX cable.
Now if you need to send DMX over a cable with XLR3 termination.
NSI / Leviton DMX 3-Pin Cable - 25' DMX3P402025 B&H Photo Video
YMMV. The product description states not suitable for digital control.
Consider buying proper DMX cable and adapting each side. I wouldn't want any XLR3 terminated DMX around my space.
I get the very rare opportunity to quasi-correct Steve Terry on something
E1.11 actually says nothing about cabling. All cabling requirements were moved to seperate documents. Those are E1.27-1 for Portable Cables and E1.27-2 for Permanently Installed Cables. Available for purchase from: ESTA Foundation - Publications - About Publications, Browse & Purchase
What E1.11 does specify are connector types that are allowed. The use of the 3-pin XLR is specifically DISALLOWED. End of discussion.
Here is what E1.27-1 says on the cable construction:
So, that's the end of what the standards say. In Europe it is very common to build single pair portable cables which is why this is included in the standard. In the US most portable cables are wired for all 5 pins. Many(most?) permanent installs do not have all 5 pins wired. Back in my day at ETC, standard procedure was NOT to connect pins 4/5 in the wall plates in installs. I do not know what current practice on their installs is.
In reality, aside from a few legacy proprietary uses pins 4/5 are not being used for anything. They are generally a landmine of incompatabilities for the few that tried using them.
In regards to shielding, I believe portable cables should all be shielded, but according to Steve Lampen from Belden at the speeds we are running for DMX512, the shielding provides relatively little noise immunity compared to the pair twisting, which is what provides the most immunity. This is another reason it is important to use proper data cables and not audio cables. Audio cables may be well shielded, but they don't have the proper twisting to provide good noise immunity for DMX512 (not to mention the high capacitance issue!).
E1.11 actually says nothing about cabling. All cabling requirements were moved to seperate documents. Those are E1.27-1 for Portable Cables and E1.27-2 for Permanently Installed Cables. Available for purchase from: ESTA Foundation - Publications - About Publications, Browse & Purchase
What E1.11 does specify are connector types that are allowed. The use of the 3-pin XLR is specifically DISALLOWED. End of discussion.
Here is what E1.27-1 says on the cable construction:
ANSI E1.27-1 - 2006 (R2011) also states that it is allowed to build portable cables that contain only the primary data pair provided they are marked with "Single pair" or "1-pair" and also marked with a violet band at least 1/2" wide within 2 inches of this marking. Of course, you still can NOT use the 3-pin XLR. You MUST use the 5-pin XLR (for what I hope are obvious reasons!)
So, that's the end of what the standards say. In Europe it is very common to build single pair portable cables which is why this is included in the standard. In the US most portable cables are wired for all 5 pins. Many(most?) permanent installs do not have all 5 pins wired. Back in my day at ETC, standard procedure was NOT to connect pins 4/5 in the wall plates in installs. I do not know what current practice on their installs is.
In reality, aside from a few legacy proprietary uses pins 4/5 are not being used for anything. They are generally a landmine of incompatabilities for the few that tried using them.
In regards to shielding, I believe portable cables should all be shielded, but according to Steve Lampen from Belden at the speeds we are running for DMX512, the shielding provides relatively little noise immunity compared to the pair twisting, which is what provides the most immunity. This is another reason it is important to use proper data cables and not audio cables. Audio cables may be well shielded, but they don't have the proper twisting to provide good noise immunity for DMX512 (not to mention the high capacitance issue!).
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