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DMX Stage Lighting Systems

If you have any experience of stage lighting you have probably used the DMX512 protocol to control your lighting rig. Apart from being able to control your dimmers, DMX lighting control is at the heart of intelligent lighting, moving lights and accessories. This article explains the basics of a full DMX stage lighting system while busting some of the myths surrounding DMX lighting control.

An Overview of DMX.

DMX XLR connector
Image by VeldaZ

Digital Multiplex (DMX) was developed as a standard digital theatre lighting control which replaced the older analogue systems that were used to control the dimmers in a stage lighting rig. Despite the advance in use of ethernet networking at the top of the professional lighting industry, DMX is still the best answer for most lighting control applications. DMX had the advantage in that a total of 512 (hence the name DMX512) dimmer channels could be controlled using only a 2-core and Ground signal cable. The other plus point to DMX was (and still is) the fact that a signal cable could be daisy chained from one DMX unit to the next and the next until all the lighting equipment was connected by one single chain of signal cables. This is particularly important when controlling moving lights as it minimises the cable required.

How does DMX work?

This article was originally called “DMX Stage Lighting Systems – Get Them To Talk” but, apart from being a bit of a lame title, this actually misses the point of the serial DMX signal. Unlike modern networks, DMX lighting fixtures and their controller do not all “talk” to each other. (If you would like a DMX system that does, take a look at our RDM DMX article)

When a DMX Lighting Control talks – everyone else listens!

Information about each “DMX Channel” (in the old days, a dimmer number) and it’s level (0 – 100%) is transmitted down the DMX “Universe” cable and each DMX stage lighting fixture, moving light or smoke machine listens for it’s own part of the signal stream and ignores everything else. The signal is then transmitted over and over in “packets”, giving a regularly updated stream for the rig to obey. The lighting console recieves no information in this one-way street.

In order for all the DMX stage lighting fixtures to have their own part of the signal stream, each one has it’s own “address” which is set on the fixture using buttons or switches. If a dimmer channel has a DMX address of 001 then it listens for the 001 part of the DMX signal then obeys the “channel level” value, 75% for instance.

Once all intelligent lighting fixtures, dimmers and accessories are connected up and “addressed” the lighting desk can control each part of the rig indiviually using their own unique DMX address.

Masters of the Universe

Back when we only controlled dimmers using DMX, life was simple. 1 DMX Channel = 1 Dimmer No. Then we started to use more complicated fixtures, moving lights and intelligent (?) lighting that needed more than 1 DMX channel per fixture. This means that fixtures are assigned a DMX “start address” which is the first channel in a sequential batch that the fixture listens to. If your fixture uses 6 DMX channels and you set it to a “start address” of 001 then it listens to channels 001,002,003,004,005 and 006. Your next free address for another fixture is then 007 because if you set it to 006 then the “channel overlap” would create a conflict of control. Setting fixtures to the same start address can be useful some circumstances and is a common method of DMX fault finding.

With many DMX moving lights requiring the use of 20 or more channels, those 512 don’t look too many now, huh? A few moving lights, 100+ Dimmers, Strobes and a couple of smoke machines and you’ve run out of channels already! The solution to this problem is to connect and address some of your equipment on a second DMX “universe”, a different signal stream with even more cables. Many lighting control desks have more than one DMX output these days and the principles of fixture addresses and channel numbers apply to this, and subsequent, universes. The first DMX channel on a second universe is also 001 and each DMX universe is a totally separate stream, independent of each other.

Myths busted about DMX stage lighting systems

Hopefully, you now have a better understanding of how DMX stage lighting systems work. A good book on the use of DMX systems is Practical DMX available at Amazon or read our review of some other good DMX books.

 

Posted by on July 18, 2007.

Categories: Stage Lighting Control

30 Responses

  1. Hi, I have disco lights with differing channels but all with dmx512. Will they connect to any dmx controller or dmx software package? Is this a recommended practise?
    Thanks

    by Riche on Mar 2, 2012 at 2:06 pm

  2. Your DMX connection should work with any DMX controller. When you say the disco lights have differing channels I assume you mean that some require 2 or 3 channels and others require 4 or more? In that case, IF you want them to show up on your control panel (manual or computer based) in sequence, i.e. 3 channels of fixture 1, then 6 channels of fixture 2, and then 4 channels of fixture 3 (a simple lighting dimmer or relay box), followed by 6 channels of instrument 4 (a gobo? i.e. RGBW,x,y), then you have to set your DIP switches (or binary starting address of each of the instruments accordingly: so fixture 1 would have a starting address of 1 and would use the first 3 dimmer channels, fixture 2 should be set with a starting address of 4 (binary DIP – off, off, ON, off, off… etc.)
    You have now used 9 channels so fixture 3 would then start at address 10 (binary DIP – off, ON, off, ON, off…etc.). Now you have used up 13 channels…
    So the next fixture (# 4) will start at address 14 (DIP – off, ON, ON, ON, off… etc.) and use up the next 4 channels.
    Then next fixture (#5) would start at 20 since #4 used 6 channels…
    You don’t have to address an ‘ending’ channel, only a starting one – the fixture or dimmer box eats up however many channels it requires and then you address the next fixture starting from there.
    Confusion arises when you have already configured things and then throw in another instrument with an address set somewhere in the middle of your existing range – then you have two different fixtures responding the the same address – so unless you intend that the two function together each fixture should have a unique starting address.
    Hope this hasn’t been too basic for you and that I have addressed the issue you intended.

    by Don on Mar 3, 2012 at 4:35 pm

  3. Hi,

    I’ve been reading a few comments on here but could do with everything being simplified as much as possible for me. I work for a drama school and have found myself always doing lights. We are based in a school who know nothing about lights so am constantly having to rewire the channels to get things to work. (I’m still working out how to make particular lights work with particular controls on the desk but I’ll get there eventually). The system I am forced to work with is from the 1960’s so as you can imagine, the (bit where all the plugs are) is really old. The lighting desk has 18 channels with only half working and with various lights paired together. We have spent last weekend unpairing particular lights and pairing them with more appropriate ones but don’t know how to unpair them. But that’s a problem which I don’t think you guys on here can help me with. What I want to know is, is it possible for me to buy a new lighting desk that can have lighting cues programmed into it and plug it into this old system? OR would that not work? Any help would be brilliant. Thanks

    by Rob on Mar 6, 2012 at 3:40 pm

  4. I think the forum would have to know a bit more about your system in order to help you with it. Back in the 60’s I worked with a couple of monstrous old analog systems with levers and twist handles, not DMX (was DMX even around then?) Have you a brand name/model for your controller? How do your fixtures connect to it?
    and the bigger question: Do you have a budget that will allow you to upgrade?

    by Don on Mar 7, 2012 at 1:16 pm

  5. Hi I have recently purchased a Behringer Eurolight LC2412 lighting console. At the moment all our lighting is analogue and our dimmer racks are furse EDM 6103. The desk has a 15 pin “D” conection for analogue 0 to +10v DC but I am having trouble making up a cable fron the 15 pin on the desk to the 2 9 pin “D” plugs on the dimmer racks. Can anybody help? PLEASE!!!

    P.S. We picked this desk so that we might step into the 21st century with new DMX lighting, but that will have to be done over a few years.

    by Peter Schofield on Mar 7, 2012 at 6:55 pm

  6. Damn, I won’t get to see the system until the weekend. Therefore I don’t know the brand name or model. I just know that it’s connected to the main patch board with kettle leads and each plug is a 3 pin 5amp plug. There isn’t a budget to replace it as it’s in the school that we are based in so isn’t our system. (I doubt the school will replace it unless I smash it….*idea springs to mind*) I just wanted to see if anyone would know from the minimal information I gave whether it would be possible to attach a new lighting board to an old system.

    by Rob on Mar 7, 2012 at 6:56 pm

  7. Hi again,
    Sorry you don’t have access to the console, but I will keep an eye on your posts as you are able to get info.
    If you are at a school, I assume that you may be part of a school system… are there any Industrial Arts teachers around that may be able to help sort out the intricacies of your existing set-up and perhaps offer to fix the faulty circuits? Maybe you could ‘sell’ it to him as an opportunity for teaching electricity and control systems…
    OK – now some guesses: you have an old system. All the power emanates from your control panel and patch board… i.e. basically all the lights are on extension cords of a sort from your control room, or in other words, if you plug in an incandescent table lamp at your patch board you can control it from your console nearby? Suggestion: cheap way of testing circuits; buy a bunch on incandescent (NOT ‘LED’) “nite-lites” from your local ‘dollar store’ plug then into your patch board and tinker with the controls to see what controls what. Saves power and craning your neck to see if a ‘real’ fixture is responding or not. (Also a lot of ladder climbing)
    It’s unlikely that any of the newer (last 10 years) systems will piggy-back onto your old system — at least the controller parts. The newer systems have mains power running up in the vicinity of where the lights will be hung, a ‘dimmer pack’ is plugged into that power source, and the lights (fixtures) are plugged into the dimmer pack. The dimmer packs are also connected in a daisy chain fashion by what appears to be, for to all intents and purposes, a dedicated microphone cable (either a 3 pin or the more recent lighting standard 5 pin plug) this cable runs back to your lighting booth and connects into your controller. A digital signal is sent by the controller to each of the dimmer boxes which in turn control the power to each of the lights connected to them. (this is expandable to up to 512 dimmer channels)
    Presumably these dimmer packs could be plugged in at your patch board; the dimmer pack plugs in to mains (uncontrolled power) and you use the old wiring to the light rails as before. But you still need to spend some money… for a DMX controller console and for the dimmer packs.
    Newer systems (short of fully computerized professional units) have the daisy chain part plugging into a converter (i.e. ENTTEC ODE or USB Pro) which in turn plugs into a standard wireless router via ethernet or a laptop. Then you purchase a program i.e. Luminair (~$130) for a laptop or iPad and run the whole system wirelessly from anywhere within your wireless range. (Sit in the audience and run the show if you wish…)
    Maybe you can talk the school into funneling the profits from your next production into a new lighting system? Bake sale? Car wash weekend? There should be a glut of old iPads on the market after tomorrow’s Apple announcement… :-)
    Roughly: $250 ENTTEC ODE (ethernet to wireless router) or $150 ENTTEC USB Pro (USB to laptop or console computer) OR stay manual at $300-400 for a 24/48 dimmer control board; $75-$250 per dimmer pack (you will need 3 or 4 to match your current level of control – they come in 4 and 6 channel per box configurations)
    I expect you could scrounge an old Intel based Mac laptop somewhere… but go for the iPad – way more cool…
    Total basic outlay 600-1000 USD
    Another idea: create or include ‘theatre arts’ in your curriculum and teach sound, lighting, stage managing, costume design, make-up, stage construction and apply for a new budget… :-)

    by Don on Mar 7, 2012 at 8:28 pm

  8. Thanks for all that information Don. Unfortunately, my drama school is completely unrelated to the actual school. We just rent the space. We are nothing to do with the school itself so have no way of sorting out their budget. But it does help to know so that I can influence the school into what they need to get. How much would you say a whole new lighting system would cost? Approximately of course. It would benefit the school for them to invest in one.

    by Rob on Mar 7, 2012 at 8:37 pm

  9. Having no idea of what you are facing, stage size, production aspirations that’s a tall order. You would do better to get a salesperson in to look at your facility and discuss what you intend to do with it. How long will you have the facility – is it worth the expenditure (for the more or less permanent parts I mean)?
    Some of the fun (and education) is working with what you have and making the most of it. Adapting a play to the facility and constraints provided has always been part of theatre.
    Basically though you have a couple of considerations: control system and fixtures (lights). I have already run you off the costs of control. eBay or Craig’s list may provide cheaper options but buyer beware applies.
    Fixtures: incandescent lamps (PARs, ellipsoidals, Fresnels, strip lights) all burn a lot of electricity and produce a lot of heat. They are also relatively inexpensive for initial outlay. They are point source lights and therefore focusable. Are electricity bills a concern? Is heat dissipation a concern? Will you require A/C to keep the place cool?
    If so, then going with more expensive and versatile, cooler and longer lasting LED lights may be the answer in the long haul, but you won’t get as many lights per monetary unit spent.
    There is also the aspect of ‘throw’ to consider and using colour – gels can be hard to find but LEDs can run the whole spectrum from the console. How many do you need to cover the space you intend to use? Is rental of extra lighting (on a per show basis) an option?
    Bottom line: you will probably end up with both styles of light for the foreseeable future… sometimes you need a focusable light and LEDs haven’t got there yet.
    For me? I’m currently in Mexico – getting ‘stuff’ can be difficult since I’m not in Mexico City or Guadalajara. I have no idea of prices where you are or the availability. Most of my stuff is brought in from the US or Canada.
    I’m in a small place (90 seats), a community theatre, we have an old manual 12/24 DMX control (Scene Setter) which is now our back up controller and we have a donated iPad running Luminaire, a donated wireless router and an ENTTEC ODE interface. This daisy chains to three 4 channel dimmers and two 4 channel relay boxes – so, in fact, I can control 20 channels but only 12 of them are dimmable. I’m on incandescent lighting with PAR 64s (8 narrow, 8 wide beam), 3 ellipsoidals, one follow-spot. I’m pushing for a budget to include some 4 channel (RGBW) LEDs since electricity and heat are issues, and we will phase out the incandescents as best we can. I’m also asking for more dimmer boxes 4’s or 6’s – doesn’t matter. (the LED units won’t require dimmer boxes since the dimmer circuitry is intrinsic)

    by Don on Mar 7, 2012 at 10:09 pm

  10. Note To Peter:
    Just had a look around – I expect you have the manual and therefore the pin-out for the Behringer unit but you don’t have the pin-in for your rack? I can’t find anything on the Furse unit either but here is a source I found that may be able to help:
    http://www.davidfitchservices.com/DocsSept09/TheInstructionsFullList.pdf
    good luck!

    by Don on Mar 8, 2012 at 3:40 pm

  11. Hi all,

    If I have a lighting system (kam led par set) using 15 channels of DMX, and buy a simple DMX console (showtec fademaster 16) is it safe to assume that:

    Consoles with 16 sliders control channels 1-16 of dmx?

    I set the first dmx channel on the lights to be 1 so….

    Everything works out of the box? channel 1 = slider 1 etc?

    or do I need to set the controller to somehow start at a DMX value?
    sorry if this is a stupid question but I really don’t have any DMX knowledge.

    by Dave on Mar 14, 2012 at 1:34 pm

  12. Attn: Rob Sayer
    I wrote back in December about an issue we were having with some Bunker DM4 dimmer boxes. I think I have solved the problem but there is still the concern about whether the engineers designing the boxes have done their job. Don’t know how to address that problem.
    Briefly, the issue was three different dimmer boxes all displaying the same fault: channels 3 & 4 had a 20% threshold – thereabouts – so there was no gradual fade in from red filament to full brightness. Why this would occur in three different boxes simultaneously suggested a controller issue – not so. Furthermore, when I took the boxes into the shop they were handed back – “no repair necessary, all is working fine” except when I got them back to the theatre.
    You need to be aware that the dimmers have two power input cords – presumably for 110V from each side of a 220V panel. After much switching of supply power sources I discovered that having both supply cords plugged into the same power source (as would probably be used on a test bench in the shop using a powerbar) the dimming worked correctly and smoothly for all four channels on the box. However if I plugged into a split receptacle (both sides of a 220V supply) the problem resurfaced.
    A simple switch around in the electrical panel gave me 110V to each plug in on any given receptacle and then the next plug-in box had the alternate side of the 220V supply. Seems that the phasing of the power supplied created the problem: as long as any given dimmer box only gets the same half of the sinewave for both power cords there is no problem.
    We’re happily back in business.
    This could be a leakage issue in the dimmer box, or perhaps there should be an inverter if two halves of the same 220V supply are used in a given box.
    There may be other readers with similar bizarre problems that this approach can help.

    by Don on Mar 29, 2012 at 2:22 am

  13. To Dave March 14:
    You have it right. There is no setting of the controller end of things… only the start address of the fixture (your 15 channel ‘kam led par set’). You can have it either with an open channel at the ‘top’ (channel 1) or an open channel at the bottom (channel 16) Presumably you would go with the second choice which would permit you to use one more channel, starting at address 16. Going with the first choice may create problems down the line since most things you might plug into your DMX will ‘eat’ four channels minimum which would have 2,3,4 overlapping with the kam unit which you may not want.

    by Don on Mar 29, 2012 at 2:34 am

  14. to Peter Schofield:

    I’ve just spent several hours today repairing our extremely creaky Furse EDM 6103 dimmers……….and will be doing more of the same over the next few days (sob sob) so if you still need the info I will make a note of it for you!

    by martyn on Apr 9, 2012 at 1:17 am

  15. Thanks for that Martyn
    I would be very grateful for the information.

    Thanks Peter

    by Peter Schofield on Apr 9, 2012 at 6:09 pm

  16. Hi.
    I am looking to get a laptop dmx controller to control my lights and allow me to expand my lighting rig. Therer are loads of free to download programmes which on the face of them seem alright….Are they?
    Also, Do i need anything else like a physical connection between the programme and the lights like a midi controller for a music programme?
    Thanks

    by Rich on Apr 23, 2012 at 4:54 pm

  17. hi Rob.
    I have purchaced for China 40 8 way DMX Dimmers and 50 16 way dimmers, is it a requirement for them to have Opto Isolation on board or is it my resposibilty to either request it or add Opto Isolators myself?
    many thanks

    Lee

    by lee on May 9, 2012 at 10:55 pm

  18. Hi,
    Im so happy of found a website like this couse Im from Colombia Southamerica and im so interested in stage lighting but her e isnt a carrer of lighting and i am in the hight school and i now colaborate in a church with lighting we have a 128 DMX channels and articles like this are very usefull for so im so happy and i have the hope that one day i will be in the other side of the stage
    THANK YOU SO MUCH FOR SHARE YOUR KNOWLEDGE TO US
    keep advancing
    From COLOMBIA Bye

    by Sebastian Romero on Jun 12, 2012 at 4:55 pm

  19. we have 2 brands of led par 56 cans 4 american dj & 6 irradient lighting.
    when daisy chained and addressed the american dj cans seem to want ttyo do their own thing. you got any suggestions.

    thanks
    steven

    by steven on Jun 18, 2012 at 5:39 am

  20. all my LED lights have 10 dip switches i want each light to be a different colour i have four lights i want them to be different so that green on one red on another blue on the other and white on the other alternating.

    by dj swizzy on Jul 21, 2012 at 4:55 pm

  21. Hi guys.. I have an event coming up that I need to use both Movers and PAR lights. My question is, can I run all movers on the same DMX daisy chain line through the Dimmer Packs out to the controller?

    Note: power of Movers are not plugged in to the Dimmer Packs – Only the DMX ins-outs.

    Thank you

    Jay

    by Jay on May 5, 2013 at 3:58 pm

  22. Yup, as long as you have enough room on the DMX Universe to address the fixtures as you want (and also don’t need more than the 32 device limit on a single DMX line).

    by Rob Sayer on May 5, 2013 at 5:49 pm

  23. Hey Rob,

    Never heard of the 32 device limit on a single DMX line before. What’s that all about?

    Thanks

    Matt

    by Matt on Feb 25, 2014 at 12:37 pm

  24. It’s in the specification. A line load can have up to 32 devices (a desk counts as a device too, so does a buffer). Every time a buffer/splitter/DA is inserted, each output then becomes another line.

    by Rob Sayer on Feb 25, 2014 at 1:40 pm

  25. Hey,

    I’m looking for a little bit of help with a problem I can’t get my head around.

    Since an (in-house) repair on some lighting units I have developed a rather strange fault.

    I have two Showtec dimmer bars and four LEDJ Omni Tri 9 all on the same universe.

    If I feed DMX to the LEDs first and then the dimmer bars everything is all ok.

    If I plug the LEDs in on their own, everything is fine.

    If I plug the dimmer bars in on their own, everything is fine and the little signal light blinks away quite merrily.

    If I then plug the LEDs in further down the DMX chain (after the dimmer bars) the LEDs work fine but the little signal light disappears from the dimmer bar after about a second and the bar becomes unresponsive.

    When I first had the problem I worked out pretty quickly that the fault was a wiring one – the pins had been crossed between the input and output in the rewire. I’ve since rectified that and the problem still presents.

    Any help!? It’s driving me round the loop!

    Thanks

    Matt

    by Matt on Mar 7, 2014 at 11:12 am

  26. Hi Matt.
    I guess my first question would be: If the system was working completely normally prior to your ‘in-house’ repairs, then what was the nature of the repair? Specifically, was there any chance of crossing the DMX wiring at some point? Then: Are you using a terminator or not? IF you drop the ‘repaired’ unit (fixture or cable) from the chain does everything work?
    There are others on the board with more expertise than me but I think they will want the same info in order to help.
    Cheers,
    D

    by Don MacLachlan on Mar 7, 2014 at 1:40 pm

  27. The repair was the replacement of DMX sockets so there is the possibility of some cross over. I have tried with termination to no avail, although the system is so small it doesn’t necessarily need termination. All of the fixtures were repaired at the same time so diagnosis by elimination is tough. I’ve tried just one fixture at a time and the fault continues. If there is a wiring fault it’s systemic in the repair and must be the same for all fixtures.

    Would a wiring cross over cause the fault I’m describing?

    by Matt on Mar 8, 2014 at 10:19 am

  28. Sorry Matt, although I may have helped in elucidating the probable source of the problem, you’re getting over my head with the electronics and engineering aspect. I can’t tell you for sure if the problem you’re encountering can be caused by a cross-over – but my gut feeling says, ‘yes’. There are others on this board with far more expertise and experience than I and hopefully they will weigh in. Rob Sayer… are you there?
    Failing that, my next move would be to find out the spec sheet connections to the replaced DMX sockets – a picture, a wiring digram, a letter to the manufacturers, a qualified repair depot – and then open up the fixtures – all of them – and make sure there are no cross-overs remaining.
    If you have the equipment and the expertise, you could check the pins on the DMX sockets to find out which pin has the digital signal and make sure that it’s consistent for all the units. While we’re here, perhaps you can let the board know if you’re using DMX3 or DMX5 and if your ‘repair’ was actually a conversion of one to the other?
    Having the signal light on for a second and then going off sure sounds like a capacitor taking a moment to charge up, so again I’m thinking cross-over fault somewhere.
    Sorry I can’t help more. Best of luck.
    Don

    by Don MacLachlan on Mar 8, 2014 at 1:34 pm

  29. Hi Matt

    You are getting help over at the Blue Room too ( http://www.blue-room.org.uk/index.php?showtopic=60755 ) and the answers there are hopefully pointing you towards a conclusion. Generally, I would advise against the idea of too much complex electronic fault finding in the field for a general lampie.

    Ultimately, my goal would be to isolate the problem and then work around it / swap the faulty item out. However, as noted above, fault finding DMX issues in a system can really test one’s ability to verify a problem as a fault can seem to move around. In the end, these things are generally either down to driver cards or wiring.
    One thing that I would consider is that just because repairs were done and faults appeared, while they may be related there is a possibility that they aren’t. Don’t discount the idea of something obvious and unrelated to the repair.

    by Rob Sayer on Mar 10, 2014 at 10:43 am

  30. Hello to all, I´m a repair man and now I started to repair a acme dmx splitter model CA-DS14, I need a circuit diagram. I have a problemas with cut´s energy, I find the fuse 1A 250V broken, I change but it follow with problems, always, when I connect the splitter cuting the fuse. thank you for your attention¡¡¡¡¡¡¡¡

    by Stuart Aguirre on Nov 13, 2014 at 5:45 pm

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