Could someone explain DMX to me please?

[4-string-thing]

With the prospect of some gigs coming up in the autumn, I've bought a few LED PAR cans to make us look a bit more interesting when we play The Dog & Duck etc. Trouble is if they're sound activated or on chase mode, I'm worried it'll look like a 70's school disco. We don't want much flashing, just gentle fades from one colour to another maybe and a bit dimmer between songs. I understand there is DMX but I don't know anything about it, or how it works. I don't want to be fiddling about between songs, and obviously we don't want a sound/lights guy to be taking a share of our fee, so can anyone explain it to me in very basic laymans terms? And what else I need to buy to get it working...

Thanks in advance!

[bonzodog]

For dmx mode you would also need a controller which allows you to program lights like have them all on a certain colour.
Do the lights not have an auto run function ? Most LEDS including ours have 3 options. Sound to light DMX and auto run. In auto run mode you can slow the lights down to change at a slower pace. This is what we do so our lights change approx every 10 seconds

[Bottle]

[quote name='4-string-thing' timestamp='1438948510' post='2838878']
With the prospect of some gigs coming up in the autumn, I've bought a few LED PAR cans to make us look a bit more interesting when we play The Dog & Duck etc. Trouble is if they're sound activated or on chase mode, I'm worried it'll look like a 70's school disco. We don't want much flashing, just gentle fades from one colour to another maybe and a bit dimmer between songs. I understand there is DMX but I don't know anything about it, or how it works. I don't want to be fiddling about between songs, and obviously we don't want a sound/lights guy to be taking a share of our fee, so can anyone explain it to me in very basic laymans terms? And what else I need to buy to get it working...

Thanks in advance!
[/quote]
Can you post the make and model of the fixtures? Not all LED PARs are created equal, but they should all respond to DMX commands in a similar way. You will need a DMX controller of some sort (if the PARs don't run off of an internal controller) and some cables (the USITT spec says 5-pin XLR but most manufacturers cheat and use 3-pin XLRs and mic cable - not recommended but it does work after a fashion)

For more info on DMX512 check out the Wiki entry [url="https://en.wikipedia.org/wiki/DMX512"]https://en.wikipedia.org/wiki/DMX512[/url]

Ta,
Ian

[4-string-thing]

It's a mixture of cheap ebay purchases, they all have auto run, dmx and sound activated, but are all different manufacturers! It would be nice to just change colour every 10-20 seconds and then have the odd one flashing a bit on more lively tunes. I'm guessing a DMX controller and footswitch would be needed?

Thanks Bottle, I never thought of Wikipedia, though I am googling DMX for dummies....

[Norris]

DMX is a bit like MIDI. A controller sends instructions on several channels and you set each light to listen to one channel - although more than one light can listen to the same channel. Different lights will need different "instructions" so only group the same type of lights together. The channel/mode is usually set on DIP switches on the back of the light.

Some lights may use more than one channel depending on what they do e.g. moving scanners will need the moving instructions as well as the colour. They tend to go from one base channel. You will need the instruction manual for each light to know how to set it up.

To control pretty much any light look for a controller that supports DMX-512. Thomann do suitable stand-alone controllers - I have a Stairville one (can't remember model) although you can get boards that plug into a laptop for instance.

Check out the "Let's Talk Lighting" thread I started some time ago as that has quite a bit of info. They can be awkward to set up initially but once you have are dead easy to use

[Damonjames]

Simple answer as stated, you will need a controller. The 512 part of DMX, is there are 512 available channels in one data cable, so you need to set the par can to a designated channel number on a binary dip switch on the back of the light fitting. You can have multiple units on one channel if you want. Once you have them addressed, you use your lighting console to control the appropriate channels. The cool thing with DMX is you can control things other than lights, like a smoke machine for example of the console (provided it is a DMX enabled unit) and you just daisy chain the lights up
Making them dead easy to setup and worries about mixing the channels up.
Hope that helps?

[TimR]

Having been down the route of controller etc I have come to the conclusion that setting them to auto with sound to light and just letting them do their thing gives fairly good results for pub bands.

The important thing with any lighting is positioning. Getting them up high and if they're LED close to the performers is key.

[LayDownThaFunk]

Well he's a rapper... oh wait.

[steve-bbb]

Think MIDI, but for lighting!

Hope this helps

[Damonjames]

[quote name='LayDownThaFunk' timestamp='1438969394' post='2839118']
Well he's a rapper... oh wait.
[/quote]

Haha,
I thought the same thing!!!

[lurksalot]

I have found the sound to light on the cans I have is next to useless , it's far to sensitive , I have recently bought a Ryger foot controller and daisy chain the lights to it , it is brilliant , you do need all the lights to talk the same Dmx language to make it run properly ie all he same make , as manufacturers often use different channels for different commands

[Dad3353]

[quote name='lurksalot' timestamp='1439019809' post='2839384']...you do need all the lights to talk the same Dmx language to make it run properly ie all he same make , as manufacturers often use different channels for different commands
[/quote]

It certainly simplifies things, but not indispensable. As long as the device receives the correct info on the correct channel, it'll work. There will be differences between different makers (nuances of colour, motor or fade speeds, flash tempo...), but pretty much all can be accommodated. The controller has to be sophisticated enough, though, to get the best from a mixed system. Just sayin'.

Edited August 8, 2015 by Dad3353

[lurksalot]

In respect to the Ryger though Dad , it is pre-programmed, so if you want the lights to do what the programme tells them to do , they all have to be talking the same language ,

[Dad3353]

[sharedmedia=core:attachments:167485]

[TimR]

[quote name='lurksalot' timestamp='1439019809' post='2839384']
I have found the sound to light on the cans I have is next to useless , it's far to sensitive , I have recently bought a Ryger foot controller and daisy chain the lights to it , it is brilliant , you do need all the lights to talk the same Dmx language to make it run properly ie all he same make , as manufacturers often use different channels for different commands
[/quote]

My cans have an adjustment knob.

I'm really surprised there are no decent programmable foot controllers out there. I keep toying with the idea of building one.

[lurksalot]

[quote name='TimR' timestamp='1439030110' post='2839478']


My cans have an adjustment knob.

I'm really surprised there are no decent programmable foot controllers out there. I keep toying with the idea of building one.
[/quote]
It amazed me too , the Ryger does a great job though, but lacks the programmability , though it does have lots of options to create a show on the fly , so I like it , my previous method was a remote control linking lights as slaves and running the master on a fade program , flooding and blackout on a hand held remote. Again, it worked ok but lacks the controllability , but the sound to light was far to sensitive even using the adjustments allowable , unless we are just too loud !!

Edited August 8, 2015 by lurksalot

[TimR]

You're either too loud or the cans are too close to the band.

I'm going to start a new thread. Please contribute.

Edited August 8, 2015 by TimR

[4-string-thing]

I do remember the other thread started by Norris, but I must be a complete dummy coz I didn't understand much of it I also never really got to grips with MIDI either...

Norris, we're from the same neck of the woods though so I may just have to pop along to one of your gigs and have a look at your system!

[Norris]

[quote name='4-string-thing' timestamp='1439053625' post='2839695']
I do remember the other thread started by Norris, but I must be a complete dummy coz I didn't understand much of it I also never really got to grips with MIDI either...

Norris, we're from the same neck of the woods though so I may just have to pop along to one of your gigs and have a look at your system!
[/quote]

You're quite welcome to. We're at the Willow in Thurmaston tonight

[bluesparky]

OOh! finally, something I know a lot about!

[quote name='Damonjames' timestamp='1438958091' post='2838986']
The cool thing with DMX is you can control things other than lights, like a smoke machine for example of the console (provided it is a DMX enabled unit) and you just daisy chain the lights up
[/quote]

Most of the smoke machines out on the market are DMX controllable, and the rest of them are usually analogue controlled either by their own custom controller or via some kind of 0 - 10V DC analogue controller. It may involve a steady hand and a soldering iron but it'd be worth it in the long run.

These can also be controlled via DMX via a little box of tricks called a DEMUX which converts the 5v DMX digital signal into old fashioned 10v (or 12V or what you need, depending on the demux's output / spec) which can control older / cheaper smoke machines, strobes etc.

Using relay units can also help you out if you want to control non-dmx items.

They'll use a DMX signal to trigger a 230V output which can power anything, i.e. fans (for keeping cool or the foot-on-monitor-hair-being-blown-guitar-solo), strobes, haze machines (NOT your usual smoke machines, as they'll need 10 or so minutes to warm up first), fuzz lights (i.e. rotating beacons) etc..


Control wise, A DMX controller can start from a £10 USB dongle, which can control 1 universe up to £40,000 desks which can do hundreds and hundreds of universes.
1 universe sends 512 x 8bit DMX "channels" at once.

Older style tungsten lights (par cans etc) use 1 channel, they only do one thing - ON! (they have to go via a dimmer, which receives the DMX signal, decodes it, and tells the tungsten lights attached to it to turn on / off / how bright they should be depending on what the controller is telling them to do)

LED based par cans start at around 3 channels (Red, Greed, Blue groups of LEDs) and can go up to a ridiculous amount depening on what they're capable of, but usually simple ones are around 5 channels (Red, Green, Blue, Intensity, Strobe effects).

Moving lights have more functions ("attributes") in them, so therefore will need more channels to control them
E.g. Intensity, Pan & tilt (movement, often these have two channels each to enable 16 Bit smoother control of them), colours, gobos (these are cut outs that are placed in the path of the light to create shapes in the beam), strobe, CMY control (Cyan, Magenta, Yellow colour mixing to enable [i]almost[/i] infinite colour control), focus ("edge"), zoom etc.

This can easily chew up dozens of channels in one moving light, so therefore the amount of moving lights you can have on one universe is greatly reduced.

e.g on one universe you can have 512 tungsten par cans, 75 or so simple LED par cans, 20 reasonable moving lights.
You can have as many combinations of lights on one universe, it doesn't matter, you use the console to patch the universe, i.e. telling the controller what is on the universe so it can send the right information to the lights.
i.e. if you have 10 led par cans, which use e.g. 5 channels each, you need to address / number the par cans with unique numbers for inependant control of them.
For ease, address them as 1, 6, 11, 16, 21, 26 etc..... The lights will have to daisy chained together to get the signal from the desk / controller to each light.
Therefore, if you have 10 x 5 channel lights on one universe the next "free" address is 56 (unless my mental maths is wrong), so you'd e.g. address a smoke machine at 56, or the first moving light at 56.

You can of course address two lights the same, but they would do EXACTLY the same as each other, which is fine. It can be used to save DMX channels if you've only got one universe of control or it can be used to minimise programming.
The way DMX works is that it simply broadcasts its signal down each universe and each light listens for the information which is relevant to it's address range (i.e. 1 - 5) and then its functions respond appropriatly. If a light isn't addressed the same as the console / controller thinks the light is patched at the light won't behave in the way you'd want it to.
You'll also get unexpected results if the console / controller thinks the light is a different type of light.
There is no standard amongst manufacurers, or even between lights from the same manufacturer, which dictates what each channel does in each light. This is usually because the lights don't do the same things, or because manufacturer's don't need to comply with others.

These days lights can have hundreds of channels (usually larger moving LED fixtures which let you control every LED individually) and larger shows can easily run into hundreds of universes of control too - the tour I was on for pretty much all of last year had a wall of LED fixtures of 179 channels each, which limited us to 3 lights per universe resulting almost 13,000 channels just for [i]some[/i] of the [i]backlight[/i]. (I have many more boring facts like that, but I appreciate no-one really cares!).

DO NO split the signal like the audio boys do, i.e. with a physical y-cord, it may work at first, but it's more often than not bad news, it won't break anything but it'll cause signal degredation and DMX reflections which will produce unwanted and unexpected flickers, flashes and blips randomly throughout the lights. The way to get more physical lines of DMX from an original single physical output of a desk is to use a buffer (splitter), which is e.g. 1 input and 4 identical outputs.

The official standard connector for DMX is 5 pin XLR but as 3 pin XLR connectors are cheaper a lot of fixtures run on 3 pin cable. DMX only uses 3 of the 5 pins in an XLR 5 pin cable.
The two spare pins in the XLR 5 cable aren't used. They were originally going to be used for two-way communication between lights and consoles / controllers so the lights could feedback to the console and update it with any errors, problems or similar.

There are 3 - 5 and 5 - 3 pin adaptors on the market which mean you can daisy chain from 3 pin fixtures to 5 pin fixtures quite happily.
As stated previously, you shouldn't really use mic or audio cable, but it can work. Personally I wouldn't advise it at all, but if it works for you and temporarily gets you out of a sticky situation then OK.
The two spare pins

There are adviseable limits on how many fixtures you should daisy chain together, thanks to signal degredation and purists will state you should terminate each "stream" of DMX. This means putting a special XLR plug called a "terminator" into the output of the fixture at end of the DMX daisy chain. The terminator has a 120 Ohm resistor inside it which helps stop the signal bouncing back down the cable and causing reflections further back up the stream of the daisy chain of lights. The reflections are usually movement twitches or colours flicking etc.
Most modern lights these days won't need terminators, but poor cable, VERY long lengths of cable, cheap lights and even having certain different manufacturers of lights having their DMX signal daisy chained in and out of each other can cause serious issues without a terminator.

There is a lot of free DMX control software out there, it's usually the hardware that costs the money but there are some bargins to be had.
Sadly, I don't know too much about foot controllers or the fixtures on the market which are suitable for pubs, clubs & smaller venues etc. but if you need any tips, advice or info about the DMX protocol, lighting in general or you're doing a gig in bigger venue / enormodrome then feel free to drop me a line!

A very quick internet search has uncovered a couple of nice little summaries of what I've said.
http://www.elationlighting.com/pdffiles/dmx-101-handbook.pdf
http://www.lutron.com/en-US/Education-Training/Documents/DMX%20webinar_7-29-2010.pdf
http://www.pangolin.com/LD2000/dmx-about.htm
http://www.marketbaba.com/svembedded/pdf/DMX-512%20Connection%20Details.pdf
I've not re-read this post back, so if there are any glaring errors, either grammatical or related to the subject of the post then it's simply due to laziness on my part!

[bonzodog]

[quote name='bluesparky' timestamp='1439063279' post='2839770']
OOh! finally, something I know a lot about!



Most of the smoke machines out on the market are DMX controllable, and the rest of them are usually analogue controlled either by their own custom controller or via some kind of 0 - 10V DC analogue controller. It may involve a steady hand and a soldering iron but it'd be worth it in the long run.

These can also be controlled via DMX via a little box of tricks called a DEMUX which converts the 5v DMX digital signal into old fashioned 10v (or 12V or what you need, depending on the demux's output / spec) which can control older / cheaper smoke machines, strobes etc.

Using relay units can also help you out if you want to control non-dmx items.

They'll use a DMX signal to trigger a 230V output which can power anything, i.e. fans (for keeping cool or the foot-on-monitor-hair-being-blown-guitar-solo), strobes, haze machines (NOT your usual smoke machines, as they'll need 10 or so minutes to warm up first), fuzz lights (i.e. rotating beacons) etc..


Control wise, A DMX controller can start from a £10 USB dongle, which can control 1 universe up to £40,000 desks which can do hundreds and hundreds of universes.
1 universe sends 512 x 8bit DMX "channels" at once.

Older style tungsten lights (par cans etc) use 1 channel, they only do one thing - ON! (they have to go via a dimmer, which receives the DMX signal, decodes it, and tells the tungsten lights attached to it to turn on / off / how bright they should be depending on what the controller is telling them to do)

LED based par cans start at around 3 channels (Red, Greed, Blue groups of LEDs) and can go up to a ridiculous amount depening on what they're capable of, but usually simple ones are around 5 channels (Red, Green, Blue, Intensity, Strobe effects).

Moving lights have more functions ("attributes") in them, so therefore will need more channels to control them
E.g. Intensity, Pan & tilt (movement, often these have two channels each to enable 16 Bit smoother control of them), colours, gobos (these are cut outs that are placed in the path of the light to create shapes in the beam), strobe, CMY control (Cyan, Magenta, Yellow colour mixing to enable [i]almost[/i] infinite colour control), focus ("edge"), zoom etc.

This can easily chew up dozens of channels in one moving light, so therefore the amount of moving lights you can have on one universe is greatly reduced.

e.g on one universe you can have 512 tungsten par cans, 75 or so simple LED par cans, 20 reasonable moving lights.
You can have as many combinations of lights on one universe, it doesn't matter, you use the console to patch the universe, i.e. telling the controller what is on the universe so it can send the right information to the lights.
i.e. if you have 10 led par cans, which use e.g. 5 channels each, you need to address / number the par cans with unique numbers for inependant control of them.
For ease, address them as 1, 6, 11, 16, 21, 26 etc..... The lights will have to daisy chained together to get the signal from the desk / controller to each light.
Therefore, if you have 10 x 5 channel lights on one universe the next "free" address is 56 (unless my mental maths is wrong), so you'd e.g. address a smoke machine at 56, or the first moving light at 56.

You can of course address two lights the same, but they would do EXACTLY the same as each other, which is fine. It can be used to save DMX channels if you've only got one universe of control or it can be used to minimise programming.
The way DMX works is that it simply broadcasts its signal down each universe and each light listens for the information which is relevant to it's address range (i.e. 1 - 5) and then its functions respond appropriatly. If a light isn't addressed the same as the console / controller thinks the light is patched at the light won't behave in the way you'd want it to.
You'll also get unexpected results if the console / controller thinks the light is a different type of light.
There is no standard amongst manufacurers, or even between lights from the same manufacturer, which dictates what each channel does in each light. This is usually because the lights don't do the same things, or because manufacturer's don't need to comply with others.

These days lights can have hundreds of channels (usually larger moving LED fixtures which let you control every LED individually) and larger shows can easily run into hundreds of universes of control too - the tour I was on for pretty much all of last year had a wall of LED fixtures of 179 channels each, which limited us to 3 lights per universe resulting almost 13,000 channels just for [i]some[/i] of the [i]backlight[/i]. (I have many more boring facts like that, but I appreciate no-one really cares!).

DO NO split the signal like the audio boys do, i.e. with a physical y-cord, it may work at first, but it's more often than not bad news, it won't break anything but it'll cause signal degredation and DMX reflections which will produce unwanted and unexpected flickers, flashes and blips randomly throughout the lights. The way to get more physical lines of DMX from an original single physical output of a desk is to use a buffer (splitter), which is e.g. 1 input and 4 identical outputs.

The official standard connector for DMX is 5 pin XLR but as 3 pin XLR connectors are cheaper a lot of fixtures run on 3 pin cable. DMX only uses 3 of the 5 pins in an XLR 5 pin cable.
The two spare pins in the XLR 5 cable aren't used. They were originally going to be used for two-way communication between lights and consoles / controllers so the lights could feedback to the console and update it with any errors, problems or similar.

There are 3 - 5 and 5 - 3 pin adaptors on the market which mean you can daisy chain from 3 pin fixtures to 5 pin fixtures quite happily.
As stated previously, you shouldn't really use mic or audio cable, but it can work. Personally I wouldn't advise it at all, but if it works for you and temporarily gets you out of a sticky situation then OK.
The two spare pins

There are adviseable limits on how many fixtures you should daisy chain together, thanks to signal degredation and purists will state you should terminate each "stream" of DMX. This means putting a special XLR plug called a "terminator" into the output of the fixture at end of the DMX daisy chain. The terminator has a 120 Ohm resistor inside it which helps stop the signal bouncing back down the cable and causing reflections further back up the stream of the daisy chain of lights. The reflections are usually movement twitches or colours flicking etc.
Most modern lights these days won't need terminators, but poor cable, VERY long lengths of cable, cheap lights and even having certain different manufacturers of lights having their DMX signal daisy chained in and out of each other can cause serious issues without a terminator.

There is a lot of free DMX control software out there, it's usually the hardware that costs the money but there are some bargins to be had.
Sadly, I don't know too much about foot controllers or the fixtures on the market which are suitable for pubs, clubs & smaller venues etc. but if you need any tips, advice or info about the DMX protocol, lighting in general or you're doing a gig in bigger venue / enormodrome then feel free to drop me a line!

A very quick internet search has uncovered a couple of nice little summaries of what I've said.
http://www.elationlighting.com/pdffiles/dmx-101-handbook.pdf
http://www.lutron.com/en-US/Education-Training/Documents/DMX%20webinar_7-29-2010.pdf
http://www.pangolin.com/LD2000/dmx-about.htm
http://www.marketbaba.com/svembedded/pdf/DMX-512%20Connection%20Details.pdf
I've not re-read this post back, so if there are any glaring errors, either grammatical or related to the subject of the post then it's simply due to laziness on my part!
[/quote]

I was just about to say that

[4-string-thing]

Wow, thanks for that bluesparky I'm not sure how much of it I actually understood, but I'll have a good re-read of it when I have more time and try to absorb it properly.... I've seen simple DMX controllers on ebay at very good prices, so I'm hoping something like that would do what we want....

[TimR]

That's a very complex explanation.

DMX is made up of 512 channels of data. The data consists of a value from 0-256. This value tells the 'fixture' on that Chanel what to do.

For simplicity a one Channel red light would be off at 0 and full on at 256. And dimmed at all values between.

A three channel par can might have Red on channel 1, green on channel 2 and blue on channel 3. Any one of 65,000 colours can be created using a mix of the three channel colours.

That Par Can would have to be adressed and then would use the 3 adjacent channels based on that address. So the Par Can at address 1 would use channels 1,2,3.
More complicated fixtures would use more channels. Add fixtures until you have used all 512 available channels.

As an example you could have 4 Par Cans set to Adress 1 and they would all operate at the same time to the same colour using 3 faders. Or you could have 4 of them set to Channels 1,4,7,10 and operate them independently using 12 faders on the desk.

Edited August 9, 2015 by TimR

[planer]

Great post bluesparky - I learnt lots there :-)

[dmccombe7]

Put your cans on a slow fade and leave them linked together and they should be enough for what you are looking for.

Next step up from that is a cheap DMX 2 or 3 channel foot controller where you can switch on the ones on slow fade and another channel for faster fade

Moving up the range with more channels you can add in some spotlights for solos, smoke machine etc

One thing i've found is the LED lights have a narrower beam more like a spot than a flood so might need more cans than the old PAR types.

Check out Youtube for more info on specific items. That's where i picked up most of it and i was new to DMX then too.
Now i have a 24 channel desk with spots, scanners, projectors, lazers and smoke machines altho it does take a bit of time to do the original programming set up.

Dave