Thread: DMX Basics

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Sorry this is such a long post, I'm hoping to answer as many questions up front as possible.

There are so many threads dealing with DMX for controlling lighting, pneumatics and such. I just finished reading a 20+ page thread on this subject and I'm still not understanding some of the basic things.

For the last few years we have run a haunt with several vsa/ssc32 controlled animated props. They are all servos in a couple of 3 axis heads, 2 axis heads and other heads with just one servo.

We bought Exorcist a couple of years ago when VSA would not play 7.1 sound. (We needed 5 props to have a sound channel assigned to it so that each individuals audio came from a speaker mounted in the prop. This worked very well.

Last year we changed our haunt from a Pirate themed graveyard where individual pirates had speaking parts to a Haunted Mansion themed graveyard where a "coachman" sat atop a horse drawn hearse with the primary speaking part and the other characters sang "grim grinning ghosts".

I split the song into two channels with our coachman singing in one channel and the ghosts singing in the other and all together in certain parts of the song. The sound separation didn't do a very good job of drawing spectators attention to just who was talking/singing.

We want to pick up some DMX lights to spot the Coachman when he is speaking and for the other props when they are speaking.

I just sent Phoenix the $ to upgrade to DMXorcist, in hopes that this will enable us to get the effect we are looking for. After reading the threads there are things that I still don't get. It looks like most people use trigger devices, we don't. We just want a show that runs, pauses for a minute or so and then runs through again.

I don't understand what connections are required between the SSC32 board and a DMX light. It seems that I need something like the Enttec DMX USB pro and I see how it is connected to a usb hub that is connected to a computer, but I don't see anything that says what connects on the other side of the Enttec. I read lots of posts about using cat5 cables, 3 pin dmx and 5 pin dmx connectors, crossovers and such. But what connects to what?

The SSC32 board has 3pin connectors on it for each channel. I understand how that connects to a servo via a 3 wire cable with whatever that connector is called. When we bring a DMX light into the picture I'm lost.

In order for the computer to be able to send out DMX signals, it needs a translator. Your computer does not have the built-in ability to transmit DMX signals. That is why you use the Enttec. You hook one side up to the computer and the other side is the beginning of your DMX chain. So, using whatever cable you've decided (I use 3-pin DMX cable) you start running the cable to the different DMX devices. It goes into the 'In' port and when you continue to the next DMX device you hook up the next DMX cable to the 'Out' port. You do this until all of your DMX devices in the haunt are all hooked up.

All of the DMX devices will have an address given to it (there are 512 of them). Most devices have a dip switch that you set to assign the device it's address.

I've never messed with servos so I do not know how they are powered. But, let's assume they have a plug. If you get a DMX Relay (4 DMX channels), you can plug the servo into that and now it will have a DMX address and you can tell it to turn on or off via the VSA program.

Hope that helps. If you haven't seen some of my videos about DMX, I can post the links here. I have one that shows how Enttec is connected and another that shows the Exorcist (DMXorcist) is connected.

LOL, BB said you'd post in this thread. I'm glad you did. Ok, I think I picture what is happening now. The Enttec box starts the signal going through the DMX devices and at the end of them is where I would assume the "terminator" goes. It is always nice to have pictures to cement things into my mind. I was just looking at all of the threads you started because I remember seeing a post of yours a long time ago about what is connected to what. I couldn't find it and would appreciate it much if you would pop a link in here. Thanks!

Yeah, it's the one technical thing I've got a good grasp on. heheh.... Yes, you need a terminator at the end to tell the DMX signaling that it reached the end.

Here's a thread where I listed all the threads I've read about DMX: DMX Tutorial

Two videos:

YouTube - Boogedy Halloween prop how-to of DMX, pneumatics, VSA and sound

YouTube - Halloween 09: Sneak Peek

By the way, in the first video I misspoke. I was using the Open Enttec..not the Pro version. I have no idea what the Pro version does over the Open version.

Thanks Terra that is perfect. I like how you throw the "why" in there. I read a lot of Phoenix's posts today and I remember him saying something about the open and pro version of the enttec. I think he said that there were issues with the open version that created problems with the way the computer recognizes signal from noise. He said that the pro version addresses the issue, but that he had written code into dmxorcist that did the same thing.

I have lots of experience with VSA in controlling servos and what you do with the lighting is not a lot different. You use channels to set light colors and timing, I use channels to set servo movement and timing.

I'm wondering now, that since my requirements don't include trigger devices, if I need Exorcist. I'm just looking to run the VSA servo routines and some DMX lights in a show that runs and repeats.

The only reason you would need Exorcist then is if you want to run different VSA routines.

Exorcist collects the different VSA routines you wrote and allows timer functions (built-in) to set them off in the order you want. If your show is just made into one long VSA routine then Exorcist shouldn't be necessary. But, you will need to hit the enter key manually to run the routine. That is where Exorcist will help you. DMXorcist allows you to run 8 shows simultaneously.

I don't know if VSA will do that either, but I'm guessing I could try and select a DMX device in VSA software and you would think, if it won't do it, it would warn me. If it won't do it, I think I will pick up a Bride of Chucky board. I like that it comes with the power supply. The SSC32 board came with nothing and I paid I think $60 for a 8 amp power supply. I'm thinking though that I needed more power because I noticed after I had everything running, that the servo movements seemed to be "weak". They didn't move as crisply or as strongly as I had programmed them. I made what I think now was a mistake. After programming each prop, I never tested them all connected prior to the haunt.

Oh, and as far as the BOC board, would it be correct to assume that the two terminals for LED connectors means DMX signal output???

You need to calulate the correct amperage required to run ALL you items. Sounds like the control board was "starved". Depending on how many servos were being powered, an 8 amps power supply may not be enough.

I ran three DMX-4 dimmer packs and an SSC-32 controlled 3 axis skull last year with VSA without any problems. I plan on adding another skull this year and at least one more DMX-4 dimmer. I use the Velleman USB, and haven't had any issues yet.

I don't think you'll have any issues running DMX and SSC-32 sequences simultaneously in a single VSA routine.

-DGM