Tyrone Blue
01-17-2007, 05:34 PM
I've encountered so many comments and questions about DMX issues, both on this board and others, that I get frustrated with posters who are purchasing DMX gear and expecting to learn programming by asking all the wrong questions in these forums.
I had a guy asking questions about addressing a scanner, and it became clear that he didn't have a clue what he was doing. I tried to answer him (in fact I did three times) and he still was going in the wrong direction.
In it's concept, DMX is very simple... you just have to know how it works. Once you do, you'll say "Ohhhh, is this all there is to it?" Simply put: DMX is a Protocol (electrical set of instructions) that allows a digital signal to run down one wire and control up to 512 fixtures/channels.
In order to make DMX work, you have to have a controller and a DMX fixture. They both have to communicate with each other. The way this is done, is to separate the DMX (512 channels) into segments on a controller. You could, in theory have 512 buttons on a controller, but this is not practical, so the manufacturers make controllers with so many of these channels split up into various buttons.
The most common controller has 12 buttons on the left that contain 16 (16 of the 512 total) signal channels for every button. Button #1 holds channels 1 - 16. Button #2 holds 17 - 32. Button #3 holds 33 - 48 and so on and so on, until you run out of channels. On the common 12 fixture controller, you run out of channels at 192.
Then, each one of these 512 channels, has a digital value running from zero to 255. Just like setting a radio dial and getting lots of frequencies on the channel or carrier frequency, you will hear music with a different frequency.
These digital values on each DMX channel determines what the function of that channel in your fixture does. For instance: a four channel scanner might have mirror pan on channel one. Mirror tilt on channel two and color on channel three. Channel four may have gobo. So, a zero setting on channel one might allow the mirror to deflect fully to the right. As you push the slider up, the mirror deflects to the left until it's fully deflected to the left with a value of 255.
Each one of these four channels will control only that function on the fixture by moving the channel slider on the controller (once you tell the controller which slider corresponds to which channel of which fixture).
That's where addressing comes in. Each fixture has 9 micro switches (or more) somewhere on the fixture. Those are the address dip switches. You set them to correspond to the "scanner" buttons on the controller. Think of it as the controller is the post office, and your fixture is the mail box with only your address.
The "heart" of the system is knowing how to address your fixtures. It's hard and easy. Like learning a magic trick. Looks cool and you say, "oh, I can do that". But you discover that you can't. What makes DMX so hard, is all of the buttons (I think). Once you understand all of the buttons, it becomes easy.
There is a right way to learn DMX and a wrong way. Coming to the boards to learn DMX is impossible. Asking where to get the information is the right way. Any good attorney will tell you that a good attorney doesn't know every law...but he knows where to find every law in a book.
If you want to learn DMX, you have to put in the effort. Everyone who does...did.
I had a guy asking questions about addressing a scanner, and it became clear that he didn't have a clue what he was doing. I tried to answer him (in fact I did three times) and he still was going in the wrong direction.
In it's concept, DMX is very simple... you just have to know how it works. Once you do, you'll say "Ohhhh, is this all there is to it?" Simply put: DMX is a Protocol (electrical set of instructions) that allows a digital signal to run down one wire and control up to 512 fixtures/channels.
In order to make DMX work, you have to have a controller and a DMX fixture. They both have to communicate with each other. The way this is done, is to separate the DMX (512 channels) into segments on a controller. You could, in theory have 512 buttons on a controller, but this is not practical, so the manufacturers make controllers with so many of these channels split up into various buttons.
The most common controller has 12 buttons on the left that contain 16 (16 of the 512 total) signal channels for every button. Button #1 holds channels 1 - 16. Button #2 holds 17 - 32. Button #3 holds 33 - 48 and so on and so on, until you run out of channels. On the common 12 fixture controller, you run out of channels at 192.
Then, each one of these 512 channels, has a digital value running from zero to 255. Just like setting a radio dial and getting lots of frequencies on the channel or carrier frequency, you will hear music with a different frequency.
These digital values on each DMX channel determines what the function of that channel in your fixture does. For instance: a four channel scanner might have mirror pan on channel one. Mirror tilt on channel two and color on channel three. Channel four may have gobo. So, a zero setting on channel one might allow the mirror to deflect fully to the right. As you push the slider up, the mirror deflects to the left until it's fully deflected to the left with a value of 255.
Each one of these four channels will control only that function on the fixture by moving the channel slider on the controller (once you tell the controller which slider corresponds to which channel of which fixture).
That's where addressing comes in. Each fixture has 9 micro switches (or more) somewhere on the fixture. Those are the address dip switches. You set them to correspond to the "scanner" buttons on the controller. Think of it as the controller is the post office, and your fixture is the mail box with only your address.
The "heart" of the system is knowing how to address your fixtures. It's hard and easy. Like learning a magic trick. Looks cool and you say, "oh, I can do that". But you discover that you can't. What makes DMX so hard, is all of the buttons (I think). Once you understand all of the buttons, it becomes easy.
There is a right way to learn DMX and a wrong way. Coming to the boards to learn DMX is impossible. Asking where to get the information is the right way. Any good attorney will tell you that a good attorney doesn't know every law...but he knows where to find every law in a book.
If you want to learn DMX, you have to put in the effort. Everyone who does...did.