Thread: DMX Basics

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@ buckaneerdude
I think most things have been covered already. There's lots of standard, commercially available, DMX fixtures (strobes, lumieres, lasers, etc) that are designed for clubs. In addition, there's purpose-built boards like mine (Medusa DMX), and the BoC. In any case, as Terra said, you just string the DMX signal from one device to the next. The DIP switches on each device set its address, so they all can be 'listening' to the same data, and will only respond to their own particular channel(s).

One correction about the Medusa DMX board, it controls (8) each of servos, LED strings, and switch outputs, not (9). As far as I know, no one other than me has taken full advantage of the LED driving capability of the Medusa. Especially for Halloween, this can be a really cool feature, because you can drive high power LEDs (see eBay, 0.5W and 1W LEDs) for real illumination (without buying a DMX PAR can). This can easily let you emulate a strobe, and even change the color from one flash to the next. I used this last Halloween to really good effect.

Regarding your question about the BoC LED outputs, these are to connect to one pair of RGB LEDs (both eyes will be the same color). They're not a DMX passthrough.

On the subject of USB-to-DMX converters, I've used the Velleman, the Enttec Open and the Enttec Pro. Unless things've changed, I found the Velleman only to be good up to ~7 or 8 channels or so. Any past that, and the whole VSA routine slows down (!) and no longer syncs with the audio. The difference Phoenix has mentioned before about the Open vs. the Pro is the Pro is electrically isolated. In setups with high amounts of electrical noise, this can leak back into the computer's USB port, and mess with the communication. Aside from these differences, frame rates will also vary. In my testing, the Velleman was the slowest, the Open faster, and the Pro is as fast as the DMX standard allows for. This translates to smoother animation, especially when you're making slow, smooth servo moves. The differences in frame rate are really obvious when using a Medusa DMX, due to the status LED on the board.

Hope this helps
- Hook

Well the posts here really helped me understand more about how all of this stuff works together. I really appreciate the input and advice. Thanks for taking the time to respond.

Mark,

The LED outputs are good up to 50V and up to 150mA (if more than one LED output is used) or 500mA (if only one LED output is being used). The same applies for the switch closure outputs. This will let you hook up some of the new 0.5W or 1W LEDs available from Hong Kong on eBay. I picked some up from this guy, and they worked phenomenally. These work great with just 5v or 12v. But if you were so inclined, you could use a 24v supply on the LEDs, and string (5) of these bad boys in a row on each LED output on the Medusa DMX.

The idea of moving the laser vortex around is awesome. I used to work with lasers for clubs, and had thought of this too. There some neat little pan/tilt stages available at hobby websites that you could use to move a front-surface mirror around. You could also use the switch outputs to turn the laser on and off (might need a relay, depending on the laser and supply). Look up 'lumia effect' and 'diffraction effect' for some other cool ideas.

- Hook

All of the stuff I ordered arrived so tomorrow I'll be playing with VSA controlling dmx routines through an enttec usb pro. First I'm going to experiment with the lights I got and once I have that working, I'll add in the dimmer to see if it will trigger the relay I bought to control a fogger.

I think I'll start with setting the first dmx device on line 33 of VSA as the first 32 I plan to use for servo control on the SSC32 board. I have to figure out the dip switch settings to get the correct address set up for each dmx light. That part seems pretty straight forward. What I don't understand yet is how to tell VSA what address I've set the DMX light to.

You set the address in the settings window on VSA:



Remember that some DMX devices are 1 address off of what you set for them in VSA. So, if you set the dip switch to 33 and the same in VSA and it doesn't work, change the VSA address one address down - see if that works and if not, set it one address up and see if that works. It's weird, I know. My Chauvet ColorSplash Jr. I didn't have to do that for but I did for the DMX relay. That's why in the VSA screen capture you see that I set the cylinder (DMX Dimmer/relay) as address 0. The dip switch on the DMX relay itself was set at address 1. Go figure I believe it has something to do with how the manufacturer decides to start his DMX addressing. Some start it at 0 and some start it at 1.

NOTE: If you see in the picture, the port setting says NONE. That is because the computer at the time was not hooked up to the Enttec. When you do hook it up to the Enttec, the drop down menu in that field will allow you to select it. A common gotcha here, we've all forgotten to do that. You will know you forgot to do that because nothing will work. Grrr....

You're such a big help Terra. You probably saved me at least an hour of frustration! I'll drop by later on with the results of my first attempts!

Hmm, no luck so far. I did notice though that the dmx lights I got are 5 channel lights. The first channel is for strobe, the second is for overall brightness and then 3,4,5 are red green blue.

Here's the instructions I got online:

DMX mode:

he 120-LED-86 is a 5 channel dmx light so you start DMX value 1. Set dip switches #1 & # 10 on the first fixture to the on position. Dip switch 10 is on to tell the light it is in DMX mode and does not have a value. This will allow the first 5 sliders on your controller to control the first light. So now set the next fixture at dmx value 6 which is dip switches #2 & #3 & #10 to the on position. This will allow you to us sliders 6 through 10 to control the second fixture.

On your DMX controller:
Slider #1 is:
0-15 = Off
16-79 = Strobe, slow to fast
80-159= Pulse strobe (fades out and back to bright, slow to fast)
160-255 = On
Slider #2- Brightness, low to high (controls overall brightness).
Slider #3- Brightness of the red LED’s
Slider #4- Brightness of the green LED’s
Slider #5- Brightness of the blue LED’s

My first guess here (because I don't know your light) is that you use the dip switches in two ways:

As DMX: So, you flip switch #10 to on. That tells the light it will be commanded by another controller. All you have left to do is then use the remaining dip switches to give it an address.

As Stand-alone: Do not flip the #10 switch to on. Use the remaining dip switches to tell it what you want it to do (be red, be dim etc.)

I believe you are merging the two different instructions together in regards to the two ways to use the dip switches.



This next part of the instruction is the perimeters of what you use to set the VSA command:

Channel 1: 0-15 = Off, 16-79 = Strobe, slow to fast, 80-159= Pulse strobe (fades out and back to bright, slow to fast), 160-255 = On
Channel 2: Brightness, low to high (controls overall brightness).
Channel 3: Brightness of the red LED’s
Channel 4: Brightness of the green LED’s
Channel 5: Brightness of the blue LED’s

Looking at the picture in my post above, see where I have under NAME: DMX Dim/strobe, DMX red, DMX green, DMX blue......that is the four channels for my first DMX light. They are all listed separately.





When you start creating 'events' you somewhat treat the 4 different channels as separate entities to program. Look at this next picture:



Here you see I am programing an event. I am setting what I want the DMX dimstrobe aspects to do (using that information that was provided in the manual for Channel 1). I decided here to have it be steady on and slowly go brighter (128 - 250 for my device). Now, I have to tell it what color I want. I have to then make another event in parallel to this one. So, for channel 2, red (on mine) I make another event and set it for high bright.

I hope that wasn't too confusing.

Terra, I guess you would be the one to ask. I've looked at dmx for about two years now. It looks pretty cool. I almost bought a board off ebay but, I noticed you aren't using one. I'm talking about the big dj boards with the slide switches and joystick. Now I'm wondering if I even need something like that? Should I just get the basic box like you have or do I need the big dj board? Thanks.

I don't exactly know what those big boards do. I think that they are used live. For example, you are the lighting guy for a band and you use the levers to tell the lights what to do. Those boards also store pre-programmed routines but I don't think they'd be practical the way we use these things. We tie the DMX light routines to VSA routines (that control solenoids and other things).

I use my computer and DMXorcist to combine the different prop's VSA routines. So, my computer is used in place of those DMX boards that you are talking about.