DMX Cabling

[zman]

Figured I would start a new thread as opposed to dragging this into the other one. For those who know better than I, I have read where standard microphone cables with XLR connectors will work for DMX. The DMX manuals state that you should not use those types of cables. I realize that could be a ploy to get you to buy their expensive jobs.

Does it really make a difference?

Lastly, is it wise or cheaper to make your own? Is it hard to make them? I have 2 or three to play with right now, but with 12 washes, 2 yokes and 2 zaps, I will need a few more.

[LightORamaDan]

When we talk to lighting pros about DMX, they all believe that cables are very important. When you only have a few fixtures you can probably get away cheap but I would be careful once you start to have a number of connections and you have significant length. Once you get a "long" run you are going to need a terminator or you will start to see random effects.

[michael.farney]

I agree with this. I did a little research and decided to try mic cable for now, but I'll switch to real cable if I have issues. Quite a few sources online suggested that mic cable will work fine for limited devices and shorter runs. The only site I found that suggested real numbers (bearing in mind I have no idea if this is reputable or not) was < 10 DMX devices, <100 feet per run, < 500 ft total run will supposedly operate OK. Terminators are probably needed too.

[iresq]

At a typical gig, I use between 6 and 12 dmx fixtures. Mostly for color wash and some scanners.

DMX cable is specifically designed for data transmission. It is usually made of double shielded (braided and foil) twisted pair conductors. DMX only requires two conductors. Most lower end DMX is run from 3 pin XLR connectors. There are also 5 pin applications. (the extra pins can be used for two way communication from the fixture, this is high end theater stuff). DMX cable is 150 ohm.

Mic cable, on the other hand, is two conductor with a shield. Better quality cables use braided shielding, cheaper cables use foil. Mic cable is 80 ohm.

Since you are passing a digital signal, you could probably even use zip cord!

Can you make it yourself? Sure. Belden 8102 cable is excellent for this application. I made custom bi-wire speaker cables with this stuff. (As a side note, these custom speaker wires were fun to make and look cool but did not change the sound from 14 gauge zip cord.)

Using mic cable? I do. Many do. I purchased a bunch of Hosa (middle end) mic cables. I custom cut several cables from this stock and added various XLR connectors (about half of my fixtures are permanently attached to trusses). I also made longer runs to provide dmx uplighting around the room.

Is it cheaper to make them? Typically no, unless you have a good source for wire and quality connectors. Are they hard to make? Not really, just need to solder a few connections. Pins 2 and 3 are used. You can tie the shield to pin 1 but it's not really required.

If you have a Guitar Center near you, try purchasing mic cable from them and try it out. They have a very liberal return policy (though there cable prices are not the greatest). If they don't work, trade up to dmx cable.

If you are the worrying type and like to do things the 'right' way, just use dmx specific cables.

[zman]

Thanks for the input. First dumb question. It looks like DMX cables will carry a bit of a premium over mic. I don't have an issue paying a bit more to be sure. As in anything are there brands to stay away from? I can go look on the web for vendors. If someone says it DMX cable, will I get DMX from them? Meaning, they could just send me mic and I would never know it. Is that my second dumb question?

[iresq]

A great vendor for this type of stuff is Bill Cronheim, Entertainment Systems Corporation (ESC http://entsyscorp.stores.yahoo.net/info.html).

He sells both stock and custom cables. If you don't see on his site, just shoot him an email. He won't steer you wrong or rob you blind. I am not affiliated, just a satisfied customer.

I checked cheaplights.com but there cables do not carry a label, probably low quality.

I see a lot of different company selling accu-cable under the names of American DJ, and Elation.

[kevin]

As with all A/V cables you can buy cheap junk and quality for a decent price. I pesonally use Mic cables for short runs (10-15ft) but I make sure they are good quality mic cables, not the $5. sets. Unfortunately you always judge cable quality by price. I've seen some very expensive quality cable that was worse than the cable half its price.


I guess the moral of the story is to use Quality cables no matter what the distance is and Mic cable can be used for short runs.

Just my 2.5 cents oppinion.

[Robin]

Ok I know all you guys know a lot more than me (since I know nothing).

However, I read a study that was performed on just this subject. Except that they tested DMX Cable and CAT5E cable. The results will surprise you. With their testing equipment they found no difference.

That study may be on a link on this site but really can not remember where I saw it now.

[iresq]

Robin wrote:

Ok I know all you guys know a lot more than me (since I know nothing).

However, I read a study that was performed on just this subject. Except that they tested DMX Cable and CAT5E cable. The results will surprise you. With their testing equipment they found no difference.

That study may be on a link on this site but really can not remember where I saw it now.

Yeah, I read that somewere also. You could use cat 5, telephone wire, zip cord, even hangers (sorry Mommy, they must be wire). You are moving a digital signal, thats all. That's why I use mic cable. It's cheap, shielded, and rugged enough.

[Charles Belcher]

Robin and all,

The theatrical lighting industry has an organization which leads the way in many ideas of which dmx over cat5e is one.

Here is the summary from their in depth study. You can scroll to the last paragraph for the conclusion if the document length makes you too dizzy.

Entertainment Services and Technology Association
DMX512 Over Category 5 Cable
Task Group Report
Summary
Prepared by Dave Higgins and Michael A.(Sandy) Twose
Edited by Mitch Hefter
CP/2000-1024
October 2000
ESTA Technical Standards Program
(ANSI ASC E1)
Control Protocols Working Group
© 2000 Entertainment Services and Technology Association
CP2000-1024-DMXoverCat5_Summary.wpd Printed: April 4, 2001
The Entertainment Services and Technology Association (ESTA) is a non-profit trade association representing
the North American entertainment technology industry. Its members include dealers, manufacturers, manufacturer
representatives, service and production companies, scenic houses, designers and consultants. The Association
addresses areas of common concern such as technical standards, customer service, equipment quality, business
practices, insurance, and credit reporting, and provides a wide variety of services to Members.
ESTA’s Technical Standards Program is accredited by the American National Standards Institute (ANSI) as
Accredited Standards Committee E1, Safety and Compatibility of Entertainment Technical Equipment and
Practices with ESTA as its Secretariat. This accreditation means that the ESTA Technical Standards Program
for standards-making has passed a detailed scrutiny by ANSI to insure that it meets the most stringent
requirements for fairness and proper public review of proposed ESTA standards. The accreditation allows ESTA
to submit standards for the ANSI public review and comment process, and then publish them as ANSI standards.
The ESTA Technical Standards Program is now the only ANSI-accredited standards-making program dedicated
to the needs of entertainment technology.
ESTA
875 6th Ave - Suite 2302
New York, NY 10001
(212) 244-1505 (212) 244-1502 FAX
http://www.esta.org
ESTA Technical Standards Manager
Karl G. Ruling
ESTA Control Protocols Working Group - Co-Chairs
Steve Carlson, High Speed Design
Steve Terry, Fourth Phase - PRG
ESTA E1.11 (DMX512) Task Groups Chair
Mitch Hefter, Rosco / ET; USITT
ESTA DMX-Over-Cat 5 Task Group
Dave Higgins, Pathway Connectivity
Michael A.(Sandy) Twose, Pathway Connectivity
Tim Bachman, Leviton/NSI/Colortran
Milton Davis, Doug Fleenor Design
Doug Fleenor, Doug Fleenor Design
Steve Terry, Fourth Phase - PRG
Peter Willis, Howard Eaton Lighting, Ltd.
NOTICE and DISCLAIMER
ESTA and ANSI Accredited Standards Committee E1 (for which ESTA serves as the secretariat) do not
approve, inspect, or certify any installations, procedures, equipment or materials for compliance with codes,
recommended practices or standards. Compliance with an ESTA standard or recommended practice, or an
American National Standard developed under Accredited Standards Committee E1 is the sole and exclusive
responsibility of the manufacturer or provider and is entirely within their control and discretion. Any markings,
identification or other claims of compliance do not constitute certification or approval of any type or nature
whatsoever by ESTA or Accredited Standards Committee E1.
ESTA and ANSI Accredited Standards Committee E1 (ASC E1) neither guaranty nor warrant the accuracy or
completeness of any information published herein and disclaim liability for any personal injury, property or
other damage or injury of any nature whatsoever, whether special, indirect, consequential or compensatory,
directly or indirectly resulting from the publication, use of, or reliance on this document.
In issuing and distributing this document, ESTA and ASC E1 do not either (a) undertake to render professional
or other services for or on behalf of any person or entity, or ( undertake any duty to any person or entity with
respect to this document or its contents. Anyone using this document should rely on his or her own
independent judgement or, as appropriate, seek the advice of a competent professional in determining the
exercise of reasonable care in any given circumstance.
Task Group Report: DMX512-Over-Category 5 Cable - Summary ESTA Control Protocols Working Group
CP/2000-1024 - 1 - Printed: April 4, 2001
Introduction
In response to a perceived industry requirement for lower cost DMX512 cable installations, the DMXover-
Category 5 Cable Task Group was formed by ESTA’s Control Protocols Working Group (CPWG) at
the January 1998 TSP meetings in Dallas. The Task Group’s mission was to employ an independent
laboratory to carry out a series of comparison tests between a typical cable presently used for hardwired
DMX512 installations, and conventional Category 5 data cable. The goal of this testing was to establish
whether Category 5 cable, or “generic premises cable” as it has become known, could be used as a low
cost substitute in permanently wired DMX512 installations.
Two series of lab tests were conducted in July and November of 1998 at MPB Technologies in Airdrie,
Alberta. Additional tests were conducted in December of 1999
Part 1 of this report (CP/2000-1024.1) describes the first series of tests which compared the DMX512
handling characteristics of a typical EIA-422 rated data cable with those of a standard Category 5
unshielded twisted pair (UTP) cable. Radiated emissions tests were also done. Results of these tests
indicated that Category 5 UTP cable performed as well as conventional DMX512 cable.
Part 2 of this report (CP/2000-1024.2) describes the second series of tests which were carried out with
Category 5 shielded twisted pair (STP) cable, and also included radiated and induced signal immunity
tests to current IEC standards on all cable types.
Part 3 of this report (CP/2000-1024.3) describes the third series of tests which were conducted to
determine the effect of combining different types of cable (i.e., Category 5 and EIA-485) on the same wire
run. At this time, tests were also done with Rosco/ET IPS equipment to determine whether the use of
Category 5 cable caused any timing problems with their talkback data.
Test Conditions & Equipment
MPB Technologies supplied a HP54510A 250MHz Digital Storage Oscilloscope and HP7475 pen plotter
to generate oscillograph plots. Radiated emissions and immunity tests were carried out in one of the
largest of their five anechoic chambers, and data was acquired by a HP8566B Spectrum Analyzer with
HP85685A pre-selector. To generate the required sweep frequencies, a HP8340A Synthesized Sweep
Generator was used; this was driven by a HP43314A Function Generator. MPB used a custom software
interface to format the output of the Spectrum Analyzer for laser printing. For induced immunity testing, a
Velonex V-3300 fast transient burst generator, in conjunction with an MPB-constructed induction clamp
conforming to IEC1000-4-4, was employed.
Gray Interfaces supplied the following equipment to facilitate the various tests:
Goddard Design Li’l DMX’ter (used for DMX512 source and error checking)
Gray DMX Repeater (isolated 1-in, 6-out buffer unit)
Tektronix TDS 220 Oscilloscope
Fluke DSP-100 LANMeter c/w smart remote
Custom-wired transceiver unit with various EIA-485 transceiver types and switchable
termination values
Custom pulse generator
300 meters (1000 feet) of each of the following cable types was purchased for testing:
EIA-422 (100 ohm) cable (2-pair with overall shield): Belden 9829
EIA-485 (120 ohm) cable (2-pair with overall shield): Belden 9842
Category 5 unshielded twisted pair (UTP) cable: Prestolite D0424 COU BL R-2
Category 5 unshielded twisted pair (UTP) cable: Alpha 9504C
Category 5 foil shielded twisted pair (STP) cable: Commscope 5NS4LAN568
Task Group Report: DMX512-Over-Category 5 Cable - Summary ESTA Control Protocols Working Group
CP/2000-1024 - 2 - Printed: April 4, 2001
Conclusion
Data obtained from all three of these test sessions confirms that, in most respects, UTP and STP
Category 5 cable can be expected to perform at least as well as EIA-485 rated data cable for DMX512
applications. Detailed supporting test documentation is provided in the subsequent parts of this report.
A separate ESTA standard (BSR E1.11, Entertainment Technology – USITT DMX512-A Asynchronous
Serial Digital Data Transmission Standard for Controlling Lighting Equipment and Accessories) is in
development which addresses implementation of DMX512 over Category 5 cable.
– End Summary –

[Dr. Jones]

All

currently the high end lighting systems use cat5 for long distance transmission. One of the benefits of DMXoE is the posibility of sending the packets along with other types of information over the same infrastructure, though most request gigabit routers and switches for the thruput of the DMX.

Several high end movers are starting to incorporate RJ45 jacks for data - Clay Paky is one example. The trend appears to be headed towards an combined resource ethernet backbone with a node or pathport converting to the common 5 pin XLR.

Cat 5 wiring has been used in lighting for several years by several console manufactures. ETC used cat5 with their legacy ETCNet. They all required an adapter to interpret the propriatary data into the USITT standard.

As for the use of mic cables for data transmission, I have had problems with low end cables. with multiple coilings and un-coilings they have had wires break internally. I still recommend making your own cables. tnb makes Procable, which is a high grade wire. I have had semi's drive over it and not break. Most theatrical stores can order or will have it in stock. If you plan on leaving it out on a wet lawn or in the sun, I would definately recommend using a higher grade cable, as it will not degrade in the elements. For my home use I use Belden's plenum grade cable, but I have it tucked up under my eaves.

there is much more - I could write pages

Hope this info helps

Chris