Control/Dimming want to learn about control

[ProgrammerInTraining]

(newbie questions inside)

thanks to you guys here I was able to learn about power distribution/ohm's law to where I was able to apply it on site, now I need to learn about control... long story short, I talked my way into getting on an upcoming show that will be keeping me busy and relieve me from the hassle of being on call, I wanna prepare myself for it the best I can, so I wanna take time to learn about control. I've been working with mostly conventional lights which I know are controlled by a dimmer rack, Ive only worked with automated lights a handful of time, just hanging them, running power and daisy chaining the dmx cable, but i still dont know where that dmx cable comes from.. is there something that the dmx connects onto before it goes to the console? or does it go straight to the console? that stuff is always handled by the more experienced techs so I dont know.. also when I asked a tech about dmx he had me lost when he was telling me something along the lines of there's x amount of channels in a universe and the his show had over 20 universes, and fixtures take so many channels and have a channel number and fixture number or something like that.. I knodded my head trying not to seem green but I really had no idea what he was talking about. I've also had an experience where I was hanging some led par-lites and a tech told me to input certain numbers on the back of the lights on the switches numbered 1-9, it was easy flipping a switch but I wanna know how he got that specific number, could that be the fixture/channel number?

if someone can point me to the right place explaining these things or even a book I can go out and buy explaining it, It would really help me out. I really want to learn this. thanks.

 

[rochem]

(Warning: long post)

Books are a great start. I'd HIGHLY recommend picking up a Control Systems for Live Entertainment, written by JohnHuntington. It'll show you the basics of all of the various control protocols we use today, but it also delves deep into how everything functions on an individual level. Automated Lighting, by Richard Cadena, is also an excellent book to learn about how moving lights are used and controlled. I own both of these, and having them on the shelf for quick reference is invaluable.

Now to try to hit some of your questions. The control protocol that we most often use in lighting is called DMX. Things can get really hairy in larger systems, but basically, you input commands into your lighting console, and the console then spits out DMX data through a cable that tells all the instruments connected to it what to do. Conventional lights are obviously not controlled via DMX directly, but the dimmers that they're plugged in to are. DMX functions by sending a continuous stream of data that repeats approximately 35-45 times each second.

In order to keep a high speed, there is a limit to how much data you can push down each data line (called a DMX "universe) at one time - this limit is 512 channels of control, thus the term DMX512. Note that this does NOT mean you can have 512 moving lights connected to every universe. Most moving lights take between 15 and 45 DMX channels of control, as they need a separate channel for intensity, gobo, gobo rotation, CMY color mixing (three channels, one for each color), and so on. So if you had a large rig of Mac 2000 Performances (which take 31 control channels each), you'd only be able to fit 16 of them (512/31 = 16.5) on each universe.

Traditionally, you can tell the difference between universes by the DMX ports coming out of the console. On the back of most consoles, you'll find a number of female XLR5 ports - these are the DMX outs. If there are 4 of those there, then you're effectively limited to four universes of output, or 4 x 512 control channels. However, more and more shows are using DMX-over-ethernet, where a virtually unlimited number of universes are sent out over the same Ethernet cable, then they split into individual DMX universes (using XLR5 cable) later on in the chain.

Remember that the console is just spitting out all this data dozens of times per second. It doesn't matter what fixtures the data is intended for, or even if the lights on the other end are plugged in. You can think of it like someone shouting instructions to a crowded room of people - the person shouting doesn't wait to hear a response, he just shouts out someone's name and their instructions, and assumes that the correct person will respond accordingly. But in order to ensure the right fixtures are doing what you want them to do, you need to give each fixture a "name" to listen for - which is called the fixtures DMX address. By flipping those switches on the LED Pars (called dip switches*), you were setting the DMX address of the fixture, telling it what control channels to respond to. For example, if you set the DMX address for a dimmer rack to 301, then the first dimmer in that rack will respond to whatever value is contained in the control channel number 301.

It's important to remember that for fixtures with more than one control channel, you're only setting the FIRST control channel that fixture needs to listen to. Using our Mac 2K Performance example, we could set our first fixture to DMX address 1, but because it requires 31 control channels, it will actually listen and respond to channels 1 through 31. We would need to address the next fixture to address 32 or greater in order to keep from overlapping. The user manual for most fixtures will give you a chart describing what functions are controlled by each control channel.

Figuring out how the correct data gets OUT of the console is also important. You may be familiar with Patching as it relates to conventionals. You (or the LD) has previously determined that a Source Four pointing Downstage will be controlled by Channel 5. When you hung that light, you plugged it into dimmer number 283. Therefore, you tell the console that whenever you type instructions for Channel 5, it should convert that into control data for control channel 283 that gets sent down your DMX cable. Moving lights and other multi-parameter devices are basically the same. The LD has determined that the Mac 2K Performance on the 1st Electric should be channel number 11. You have set DMX address 445 on the unit itself. You just need to tell the console that any instructions for Channel 11 should be converted and sent down the line as control channels 445 through 476. On most modern consoles, the console will figure out what specific channels to send information down in the range that you've selected.

Having 20 universes on a show is very large, but not extremely uncommon. Sounds like you were working on a pretty big show. Fixture number doesn't really fall into this discussion, but I'll answer that just to avoid confusion. On the GrandMA series of consoles, you can assign either a channel number OR a fixture number (or both) to every light you're controlling. This has lots of advantages in the programming phase that I won't go into here, but for the purposes of this discussion, Fixture number and Channel number basically mean the same thing.

*Dip Switches - more modern fixtures usually have LCD screens or numerical displays to set the DMX address anywhere from 1-512. Older and less expensive products sometimes have dip switches, which do the same exact thing except they are setting the address using binary. In this day of technology, you can download a free app for your phone that will automatically show you the correct dip switch setting to use for a given DMX address.

There is a LOT more I could go into about DMX, but this should be enough to give you the very basics. I'd highly recommend picking up one or both of those books to learn much more from people much more knowledgeable than I. Hope that helps!

 

[kicknargel]

Read through this stuff (and more) from Doug Fleenor Design, then ask about specifics you're still unsure of.

Doug Fleenor Design - DMX Primer

Doug Fleenor Design - DMX Basics

 

[derekleffew]

Start by looking up some terms in the CB wiki: DMX, address, dipswitch, opto-splitter.

Obtain the book Automated Lighting by Richard Cadena (but you can probably skim past the history portions, as well as the electro-mechanical sections, unless you desire to be a ML tech).

 

[kicknargel]

Wow, rochem's way less lazy than me.

 

[DuckJordan]

Wow, rochem's way less lazy than me.

or way more bored.

Also most techs if its not a extremely hectic time would rather you ask questions than to walk away with no more knowledge than you have. I'm actually teaching the guitarist for the band I'm running their Production front to how DMX and his fixtures work as well as teach him easier way's to use the console they have.

Long story short, He asked a question unsure if he should, I took the time to answer. I know in the area I am most will literally stop everything they are doing and strike a teacher pose. (its quite funny) But in all seriousness asking questions from people who know what they are doing or have had experience is the easiest way I find to learn things.

Rochem's post was a very good brief description and don't expect to get everything right away. The doug fleenor stuff is always good to come back to as well. And a Concur with getting automated Lighting programmers handbook its very well put together and isn't so massive you feel overwhelmed.

 

[TimMiller]

When setting dip switches to set a dmx address it goes by binary code.
In order of switches being turned on (they are labeled 1 thru 9)
Switch-dmx channel
1 - 1
2 - 2
3 - 4
4 - 8
5 - 16
6 - 32
7 - 64
8 - 128
9 - 256

Some fixtures automatically assume 1 so when you turn on switch 1 the dmx address is 2 others do not so you must set switch 1 to assign dmx channel 1. You add up the binary numbers to assign what the dmx channel is. So if you want do assign a light to dmx channel 14 you would turn on switches 8,4,2. Also there may be an extra switch on group of switches. These will set certain attributes within the light such as if it is an led par dip switch 10 may turn on and off sound active mode.

 

[jglodeklights]

The other thing to keep in mind when talking control is the Console you will be working with. Depending on venue scale, age and budget, there are dozens of options as to what they could be using, each with its own syntax and method for working with. Finding out what console(s) you will be working on is extremely important. The way you program an ETC Express is different than the way you program an ETC Element, and an Element is programmed differently than an ION and EOS despite the fact that all three consoles are running EOS Family software. When you start branching out into different brands such as Strand, HOG, Grand MA, Martin, Chamsys Magic Q and others, things get even more messy. Then you learn that the production is working with an older or different version of the console software than you learned about or on. For example, I first learned to program the ETC ION with software version 1.3/1.4/1.5. They are now on 1.9.6/1.9.8 Beta. I had to almost completely relearn some of how to navigate on the console.

Learn as much as you can by reading the manual, watching online tutorials, and playing on if possible in regards to the consoles you will be working on.