Illuminating DMX: Part 3 B- DMX Protocol Charts vs Faders

What Are We Trying to Accomplish?

In my last blog we talked about DMX Protocol, or implementation charts. They're basically a list of parameters that can be controlled with a DMX controller. In this post we're going to look at how faders on a basic controller transfer to controlling parameters on a moving head light.

Something To Note:

I have forgotten to mention this important fact in previous posts.   DMX transmits data in 256 steps, in numbers ranging from 0 to 255. So if your fader is all the way down at zero, you're sending number value 0 down that DMX channel.  If your fader is at 100 %, all the way to the top, then you're transmitting number value 255. Certain parameters in a lighting instrument are looking for a specific value to perform a specific function. For example on a Chauvet Q-Spot 360, if you transmit between values 10 and 19 on channel 6, you tell the color wheel to rotate so that the light's output will be red.  If you change that value to 47, the color wheel will turn to blue.

What Are We Using?

I initially thought about using a higher end instrument like a Robe Robin DLX Spot, and a Chauvet controller for our example. I thought about it, I decided to go with a more affordable lighting instrument that a band or small club might have. I also decided to go with a non-programmable controller that would still be fairly common. This wouldn't be the ideal situation at all, and we'll get to why eventually. Here's what we're using

Light:

I recently special ordered a Chauvet Q-Spot LED 360 (www.chauvetlighting.com) for a customer. They are using for a travelling trade-show booth.

Controller:

For our illustration, I'll use an "Super Basic 5000 mk MCDXII Universal DMX Controller." It's a completely made up 16 channel controller. They don't really exist but it was easy to draw in the software I use. I chose this because I can create a basic drawing with faders and label them. This will help you visualize how the faders will correlate to parameters on the light.

We'll pretend it's similar to aLeviton (Formerly NSI) N7016-D00 Console (www.leviton.com) because it is a fairly common console to find in houses of worship. It's a basic 32 channel DMX controller. You can either use it to control 32 channels, or control 16 channels and have two scenes.  That's it. 32 channels of control. No programming. Two scenes. They were really designed to control dimmers, but today we're connecting a mover to it.

What Do We Need To Know?

I always recommend reading the manuals first. This will at least get you in the ball park on how to operate your gear. For our example we'll assume the manuals have been read.  Let's take a look at our equipment.

1. Our pretend 16-channel controller controls 16 DMX Channels. Since it's not a very fancy controller, there's no LCD Display to tell us what value we're transmitting on each DMX channel. The basic Leviton controllers work the same way.
2. The Chauvey Q-Spot 360 can operate in two modes. On this instrument they're called personalities. Other manufacturers call them modes. It's important to note that we can run this in an 11 Channel mode or a 14 Channel personality (mode). This dictates how many DMX channels the instrument uses. (Manual Here.)

How Do We Do This?

1. We'll need the DMX Protocol Chart for the Q-Spot. It's in the manual. We'll need to look at the 14-Ch personality.
2. We need to connect the power cables, DMX cables and power things on.
3. We need to properly address the Q-Spot. Since our controller only goes up to 16channels we have to stay under address 016. We also have to keep in mind that we're running the light in 14 channel mode, so, for example,  if we address it at DMX Channel 013, then then we'll only be able to control 4 of the light's parameters. That means there's 10 things kinda hanging out there that we have no control over what so ever.  For this example, we'll address the light at DMX address 001. That way fader one will control the first parameter, fader two will control the second parameter and so on.

The picture below shows our basic controller. Each fader is numbered, and labeled indicating what parameter of the Q-Spot it will control.  Hope this helps!

~Andy

Illuminating DMX: Part 3 A- DMX Protocol Charts

What is a DMX Protocol Chart?

In basic terms you could think of a DMX protocol chart as an address book. They list what paramater of a lighting fixture is controlled at each DMX address. The charts are usually found in an instrument's owners manual.

Why Do We Need to Know This?

If we look back at  "Illuminating DMX: Part 2- Addressing", there's an example using a simple controller, two dimmer packs, and some par cans. One lighting instrument was controlled by one fader on the controller.  This was a typical system a few years ago.

Recently  however, LED lighting systems, and moving head (often referred to as movers) lights have gotten extremely affordable. These instruments use multiple DMX channels, and therefore multiple faders. The chart will tell you what fader to move to control which function of the light.

What Are We Controlling?

The functions of a lighting instrument vary from manufacturer to manufacturer. They can also vary depending on what mode the instrument is operating in. Some units even allow you to change the number of channels they use. Let's take a look at some of the parameters.

We'll start with some typical mover parameters:

1. Pan- this turns the head of the mover. Like shaking your head "No."
2. Tilt- moves the head up and down. Like shaking your head "Yes"
3. Zoom- changes the size or diamater of the projected beam of light
4. Focus- Changes how sharp the projected beam of light or image from the light appears. Similar to focusing a projector
5. Color Wheel(s)- Some instruments have a wheel with fixed colors such as red, blue, green, violet, etc. This paramater would turn the wheel to the selected color. Others use a series of three wheels to mix colors.
6. Gobo- A Gobo is a metal or glass piece that has a pattern on it, that Goes Between (hence the term Gobo) the lamp and the lenses that project an image, or can break the light beam up so it makes neat patterns in the air. A classic yet semi flawed example of this is the search light Commissioner Gordon uses to signal Batman.
7. Dimmer- This one's pretty straight forward. It changes the intensity of the light blasting out of the instrument.

And now some typical LED wash light parameters:

1. Red- Changes the intensity of the Red LEDs from 0 to 100%
2. Blue- Changes the intensity of the Blue LEDs from 0 to 100%
3. Green- Changes the intensity of the Green LEDs.
4. Color Macros- Depending on what DMX value is transmitted, this will change the light to a pre-set color. This paramater usually overrides the Red Blue & Green (RGB) settings.
5. Strobe- makes the instrument flash.
6. Auto Programs- this will engage some built in color change patterns
7. Speed- This will change how fast the auto-programs cycle.
8. Dimmer- This would function as a master dimmer for the instrument

So What's Next?

For the next post in this series we'll take a look at an actual DMX Protocol chart and break down each paramater and how that relates to faders on a controller...  Stay tuned!

~Andy

See Illuminating DMX: Part 2- Addressing here.

Continue to Illuminating DMX: Part 3B- DMX Protocol Charts vs Faders here.

Illuminating DMX: Part 2- Addressing

Why is it So Complicated?

The simple truth is, DMX isn't that complicated. We just need to take some time and understand our equipment. Different lights or dimmers use different quantities of DMX channels. For example a Lightronics AS-40D uses four DMX channels.  A Robe Robin DLX Spot moving head fixture uses up to 35 channels.

The trick is to make sure you have enough control channels to control the number of lights you have. For example an NSI/Leviton N7008-D00 is a common 8/16 Channel DMX controller. Maxed out, this little guy will control up to 16 DMX channels.  It wouldn't be wise to attempt to control the Robe with this controller. But the Leviton should work just fine for a small band playing at a local bar.

A Look at a Basic System:

As an example let's break down a "Weekend Warrior" rig from a few years ago. This would be the typical bar band set up:

(8)  PAR56 Can lights with gels(color filters)

(2)  50 ft DMX Cables

(2)  Four Channel Dimmer Packs

(2)  Lighting Tree Stands

(1) Eight Channel Lighting Controller

Let's set it up. We've got four lights on each tree. There is one dimmer pack on each tree. The controller is in the back of the room near the audio console. Each fader on the controller controls 1 channel of DMX. So fader 1, is DMX channel 1,  fader 2 is DMX channel 2 and so on.   Our signal path for our DMX signal would look like this:

Controller  => 50ft DMX Cable => 4 Channel Dimmer Pack One => 50ft DMX Cable => 4 Channel Dimmer Pack Two

Example One- Dimmers With the Same Address:

Each dimmer pack has 4 outlets on it connected to one dimmer each.. Each dimmer is controlled by one channel of DMX data. It is also important to note that because of this each dimmer pack uses four channels of DMX.  If I give both dimmer packs the address of 001, then when I push fader one on the lighting controller, then light one on both dimmer packs will come on. That patching would look like this:

Example 2- One Fader Controls One Light:

If we want one fader to control one light, then Dimmer Pack One should control lights 1-4, and Dimmer Pack Two should control lights 5-8. So our patching should look like this, if we address the dimmer packs with addresses 001, and 005:

Example 3- Overlapping DMX Addresses:

Here's another example illustrating what might happen if we make a mistake assigning addresses. Let's say we gave Dimmer Pack 1 the address of 001, and Dimmer Pack 2 the address of 003, some of our control channels will overlap like this:

Note that fader channels three and four control lights on both dimmer packs. If I push Fader 3, then it will control lights 3 and 5, and fader 4 will control lights 4 and 6.

Wrapping It Up:

Again, we're taking a very simple look at things right now.  We'll continue to look at things more in depth over the next few months.

~Andy

See Illuminating DMX: Part 1- The Basics Here

Continue to Illuminating DMX: Part 3 A- DMX Protocol Charts Here