FAQ

So here it is, hopefully this can help eliminate a lot of repeat threads and can add to it as needed.

FAQ Terms

Chase – Series of scenes repeated with times in between each scene and sometimes a fade time (though if it has a fade time, it technically is a show).
Console – A DMX Controller that uses a hardware interface vs a software one (MyDMX, CompuLive, etc).
Conventional Fixture – A fixture that only has a tungsten source lamp in it. Examples include but not limited to Par Cans, Pin Spots, Fresnels, etc.
Cue – A scene that belongs to a cue stack.
Cue Stack – A series of cues that allows more control then a show. For example, you can generally control fade up times, fade down times, tell cues to follow each other like a chase/show, or tell cues to advance manually. Higher end consoles offer even more control then this with regards to timing and even higher still allow for more than one cue stack.
Dimmer Pack – Portable devices used to control the intensity of conventional lighting fixtures.
Dimmer Rack – Larger form of a Dimmer Pack and also capable of having many more dimmer channels (up to 96 vs 6 on a Dimmer Pack)
Dip Switch(es) - An analog way of setting DMX addresses and stand-alone fixture control. Each switch does something different fixture to fixture so check your manual for details. 1-9 are used for DMX addressing when in use for all fixtures.
DMX – Control standard for lighting in the Entertainment Industry. It stands for Digital Media Extension.
DMX Addressing – Assigning/Assignment of DMX Channel/s to fixture/s and/or dimmer pack/s and/or rack/s for control.
DMX Chain – A series of DMX Fixtures and/or Dimmers connected via DMX cable.
DMX Channel – Numbered 1-512, it is the number given to fixtures for control.
DMX Controller – Device used to send DMX signals to control DMX fixtures and dimmers.
DMX Fixture – This is a fixture that doesn’t plug into a dimmer pack/rack for control. It instead get’s control through DMX cabling.
DMX Universe – 1-512 channels of DMX, higher end controllers/consoles can have more than one to control more fixtures.
Fixture – Another term for a light, such as a par can or an Accu Spot 250.
Fixture Profile – Used to control DMX Fixtures with more ease. Dimmers (packs and racks) do not need a Fixture Profile to work, they just simply need to be patched or given an intensity channel depending on console.
Intelligent Fixture – A DMX Fixture. These fixtures also generally use more than one channel of DMX. The difference between a DMX Fixture and an Intelligent Fixture is that Intelligent Fixtures have the ability to move the beam of light, or Mover.
LED Fixture – A fixture that uses LEDs as lighting source vs lamps. LED fixtures are DMX fixtures.
Mover – A DMX Fixture that can move the beam of light it projects. Also known as an Intelligent Fixture.
Patching – Matching of the DMX address to DMX channels on controller/console. Also, it is the setting of Fixture Profiles so that they line up with their respective fixtures.
Scene – A ‘look’ of lights. For example, an all red stage can be considered a ‘Red Scene’ and/or ‘Red Look’. The terms look and scene are interchangeable.
Show – Similar to a chase, be generally allows for longer periods of time in between each scene as well as fade times/longer fade times.


FAQ

What is the difference between DMX and XLR/mic cable? What does it matter if I use one over the other?

DMX is 110-120 ohm digital cable that comes in 3 pin and 5 pin configurations. According to the standard, only 5 pin configuration is suppose to be used. 3 pin cable can be used however because DMX only needs 3 lines to work and not 5. XLR/Mic Cable is 300-600 ohm analog cable. It is capable of transmitting DMX over short distances generally. However, even at short distances, Mic Cable can cause fixtures and dimmers to act erratically or not even respond at all. There is also not set guild line for this to happen; it can be as short as a 5’ Mic Cable in some spaces that causes issues.

What is a terminator? Do I need one?

Terminator is simply a 120 ohm resistor that is less than or equal to 2 watts between pins 2 and 3 on the very last fixture/dimmer in your DMX Chain. DMX Terminators stop what are known as DMX reflections. DMX reflections are when the signals transmitted by the DMX controller/console reaches the end of the DMX Chain and literally bounce back down the DMX Chain. This can cause unwanted and erratic behavior. A Terminator solves this problem.

Terminators can never hurt a system unless using Mic Cable (since the resistance value is different and you shouldn’t be using Mic Cable in the first place) or if the last fixture in the DMX Chain is self terminating. This means the fixture automatically adds 120 ohm resistor in line when it senses it is the last fixture. Adding another resistor then doubles this resistance and can cause issues as seen with using Mic Cable. Refer to your manual to see if your fixture/s are self terminating, though this is only common on very high end fixtures.

I am lost/confused about DMX Addressing and Patching, help!

Think of DMX addressing and patching like the post office. The address is you put on the letter is the patch. With the wrong patch, the package doesn’t get to where you want it to go, just like putting the wrong address on a letter. Next, the post office sorts the letters by their addresses and sends them out for delivery. This is like your DMX controller, it sorts your commands and your patch and sends out the signals to your fixtures. Then the mailman takes the letter for delivery, which is like your DMX cable. Last, the mailman deliveries the letter to the address on the letter. This is like the DMX cable taking the signal from the controller to the fixture at the patch specified. But if your address changes, the mailman drops the letter off to the wrong place. So if the address on the fixtures are wrong, the signals don’t get through or go through wrong.

Next, how to address. Addressing is relatively easy, just have to be able to add. Say you have two 6 channel fixtures and a couple of 4 channel dimmer packs. You want your dimmers to be first in line, then your fixtures. Set the first dimmer pack to channel 1 and the second to channel 5. 4 channels for the first pack, channel 1 is 1st dimmer, channel 2 is 2nd, 3 is 3rd and 4 is 4th. Your next pack starts at your next available channel, which is 5. So channel 5 is now the 1st dimmer of your 2nd dimmer pack, channel 6 is the 2nd, 7 is the 3rd, and 8 is the 4th. Now your two 6 channel fixtures. Since the 2nd dimmer pack ended at channel 8, we would address the first fixture to channel 9. The 2nd fixture would then be channel 13 since the first would end at channel 12. You can change this in anyway however. For example, I can leave my dimmers addressed to channels 1 and 5, but address my 6 channel fixtures to channels 101 and 107 if you wanted. Or if you wanted both dimmer pack to do the same thing at the same time, you can address them both to channel 1 so that channel 1 controls the 1st dimmer on both dimmer packs. Or you can set it so that both of your 6 channel fixtures are channel 1 and your dimmers start at channel 7. You can configure DMX anyway you want, just don’t overlap values so that there are issues with control. For example, if you set your fixtures to channel 1 and dimmers to channel 5, when you bring up channel 5, the 1st dimmer on your dimmer packs and channel 5 on your fixtures will come on. Channel 6 would be the 2nd dimmer and 6 channel on your fixtures.

My fixture isn’t responding/not working right. What is the problem?

First, DMX cable. Make sure you are using DMX cable and not Mic cable. Also try adding a terminator. Next, check your addressing and patch. Make sure your channels are in your patch are matching up with the addresses on your fixtures. If they are, check to make sure you are using the right fixture profiles and also check the fixture settings (a lot of fixtures have options for 8 bit/16bit control which changes the number of channels). Also make sure that your fixtures are set for DMX and not standalone mode. Beyond this, it could be an issue with the fixture and/or controller, so ask a question and hopefully someone can help.

What is a DMX Splitter/Isolator and do I need one? Can’t I just use a Y-Cable?

To understand why you can’t just use a Y Cable, you have to know a little bit about circuiting. A Y-Cable makes a parallel circuit, which keeps the voltage the same but changes the current. So basically, one line would have more current then the other based on the amount of fixtures on it. This basically means that the signal down one line would be stronger than the other, which than causes control issues.

A DMX splitter/isolator serves 3 functions. First and most obvious, it splits a DMX signal into 2 or more lines. This is not the same as adding another DMX universe, but rather taking one universe and splitting. Next, a splitter isolates the lines. Say there is a power spike on the fixtures on line A in your splitter that blows out the DMX controllers on that line. That power spike won’t cross over to lines B, C, D, E, etc or back to the controller, effectively saving you quite possibly your show and a boat load of money. This isolation also stops DMX reflections from line A effecting line B, C, D, etc and the controller. The last thing a splitter does is it boosts DMX signal. At around 1000’, DMX signal starts to fall off. Generally lengths of 500’ or more, it is highly recommended that a splitter is used. At around 200-300’ is typical for most people to start using one.

Now, do you need one? Well, that depends. First, do you need to split the signal for any reason? If you do, you need a splitter. Second, are you using long lengths of DMX? If you are, then you should use a splitter. Third, DMX is very resilient when it comes to electrical and outside interference, but some spaces have issues with that and a splitter would be beneficial. Also, if the room has issues with power fluctuations and/or bad grounding, a splitter would help eliminate interference with regards to bad power. DMX fixtures, depending on how bad the power situation is, want to be on the same ground as the controller generally. A splitter effectively works like a ground lift and can solve problems.

Can I plug my xxx into a dimmer to turn it on and off?

No. I explain in depth here as to why exactly. It is a bit of a read and there is some math involved, you have been warned Wink. You can plug these fixtures into DMX switches. Some DMX dimmer packs have this option. Please look at your dimmer pack manual to determine this and have it set to this mode when using non filament lamps in them. If not sure whether or not your dimmer pack/s and/or dimmer/s you are looking to buy have this option, feel free to ask and myself and/or someone will be glad to help.

What is the difference between 16 bit and 8 bit? Advantages and disadvantages?

One channel of DMX can send 256 different signals which is 2^8 or 8 bit. A 16 bit signal combines two DMX channels for 65,536 signals or 2^16.

16 bit allows for much better control of features. Pan and Tilt are the most common features to be 16 bit. Any feature on a DMX fixture can be however. For example, Elation's Deisgn Spot 1200 has 16 bit control over Pan, Tilt, Color Wheel, CYM, CTO, indexing on both gobo wheels, prism indexing, Focus, Zoom, Dimmer, Iris, and Frost.

8 bit has the advantage of using less channels at the expense of control. The Deisgn Spot 1200 example above in 16 bit extended mode uses 38 total channels. In standard mode with 16 bit on only Pan and Tilt, it uses 26 channels. Then in basic mode with no 16 bit control at all, it uses 24 channels. In the end, it comes down to preference. However, most fixtures that have 16 bit control can disable and enable it, so it is never a bad thing to have because you have the option of turning it on or off like the Design Spot 1200. See your manual for specifics as to whether or not your fixture/s have this and if it can be enabled or disabled.

How do I use dip switches? How do I set up a DMX address with them?

To start, dip switches have two positions, on and off. On, they effect the fixture and off they don't. Common numbers include 10 switches, 12 switches, or sometimes more (Coemar ParLite LED for example has two banks of 8, for 16 total). What each switch does is unique fixture to fixture. Check your manual for what each switch does and how to get the fixture into different modes. Some fixtures has instructions on the back of the fixture for what each switch does and its modes.

DMX mode is commonly activated by simply plugging in a DMX signal into the fixture. This cancels any stand-alone commands/operations as soon as the fixture sees DMX signal. For addressing, dip switches 1-9 are used. It is a binary system, so each switch doubles the value of the switch before it.
Switch DMX Value
1 1
2 2
3 4
4 8
5 16
6 32
7 64
8 128
9 256

To get a DMX address, simply turn on the switches that add up to the DMX address required. For example, a DMX address of 1 would simply be dip switch 1 on. A DMX address of 41 would be dip switches 1, 4, and 6 on. 100 would be 3, 6, and 7 on. Other dip switches generally aren't used in DMX mode. Sometimes, another switch may control channel count. For example, on Elation's Deisgn LED 36, the twelfth switch in DMX mode controls channel mode, 3 channel or 6 channel operation mode. Again, consult your manual to see if your fixture has such options available to it.

There are a few dip switch calculators available online as well as some phone apps for them too. These let you enter an address and tell you which dip switches you need on. Elation's own Dip Switch Calculator can be found here for download. A couple of quick notes/tips/tricks:
1) If the address is odd, it will always have switch 1 on.
2) If the desired address that is a number before the next dip switch, for example 63, turn on all the switches before that switch. So 63 would be switches 1 through 6 on.
3) Using the technique listed above, you can subtract switches backwards. For example, if 61 is desired address, turn on switches 1 through 6 and then turn off switch 2, effectively subtracting 2 from the address total.
4) All dip switches on will give an address of 511. Again, starting this way, simply subtract from 511 as switches are turned off.



Disclaimer I am no no way affiliated with AMDJ and/or AMDJ Family of Companies (including but not limited to Elation Lighting, Acclaim Lighting, Global Truss, American Audio and Antari). As such, my statements above do not reflect the opinion of AMDJ and/or AMDJ Family of Companies. I am just a lighting guy trying to help some people out is all Wink. And if your question isn't answered here, by all means, ask. I will add to this as more and more common questions pop up/people make suggestions.
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