What DJ's want from DMX and how intelligent can DMX be?

Hey Bill and welcome to the forums.

When you put fixtures in Master/Salve mode, the master actually becomes the controller and sends out DMX signals to the other fixtures. This idea would be basically impossible to implement on DMX, since the Master would send out signals and then the DMX controller would as well. You would have two conflicting signals and the fixtures would then response in an odd manner.

If you are getting a delay between fixtures, you have another issue then. You are not using DMX cable, using just a USB dongle (weak signal), have too many fixtures on a universe (DMX is limited to 32 per universe), or have another issue somewhere (like a voltage drop). DMX signal travels way too fast for there to be any delay. I have done as much as 12 fixtures addressed the same and not had an issue with response times.

There is not a hard limitation of 32 fixtures per DMX universe. A Universe is 512 channels.

Impedence load per run dictates that you should try to have no more than 32 DMX fixtures on a single chain, without incorporating some sort of corrective device.

To address Serra Ava's mostly correct observation about signal strength coming from a dongle, I take it a step further. An affordable device such as the Elation opto Branhc/4 and Multi-Branch/4(same thing, one is a rack unit, the other a box) can take such weak signals and boost them to proper signal strength.

Also, in support of Serra Ava:
I had a gig last night where some front row hugging dummy decided "hey, buttons on lights, must press" threw a Mega Panel into some odd mode. It then screwed up the other 3 Mega Panels down the chain and the 4 ADJ 64 LED Pros also further down the chain. In some modes, fixtures act as stand-alone controllers, so I was in a random-type master/slave thing going on.

Master/slave issues have been discussed here at length. This is always a sound active mode thing. Look, when you're in DMX mode, and you place a fixture into sound active mode via the DMX traits, each fixture operates independently in sound active mode. If you want control you have to create control.

Well I would say the only thing that I am guilty of is running 50 feet of XLR cable. I have 6 fixtures on it. You really think a delay issue would be caused from that?

It's just weird...even when I put the controller in Single/Mix Chase I still see a delay stutter like information is being transmitted and interrupting the flow of the lights.

What pins and voltage should I be seeing on the cable? Would you have a link where I can see video and 12 fixtures with all the same DMX address?

Mic cable or actual DMX? Yes there is a difference and i have seen it first hand.

I guess what I am asking is what causes delay within DMX. Impedance and interference would probably make the fixtures shake or flicker. I would like to see maybe a video on the two if anyone knows where I could find one.

Describe your chain in detail.

Yes, XLR mic cable can cause problems. I've never experienced any, but to avoid risk, I use DMX cbale now exclusively for my lights.

Last night, I ran this configuration:
Compu Show to Opti Branch/4
Opti Branch 4 to a 200-foot spool of Accucable.
From there, 25-foot run to first tree of 4 ADJ 64 LED Pros. Each connected with 3-foot cables between them.
25 foot cable run donn the tree to a mega Bar 50. This was chained to 7 more ADJ Mega Bar 50's by 3-foot DMX cables. 25-foot run UP to the next 4 ADJ 64 LED Pros. The last can had a terminator in it.

FLAWLESS

(until some retard in the front row started dinking with a Mega Bar 50, threw it into some stange mode and it stopped work, but only after they changed the chanenels first.

I don't have any videos of issues or when I have fixtures addressed the same, however here is an excellent video talking about DMX cables and why they are different from mic cables.

I noticed a delay on the last 1/3 of my run on my pars. The terminating plug at the end of the last fixture helped a little. Now that I have more fixtures the Elation opto banch seemed to give a boost to the signal and now they are all in sync when they change color. So I do believe in using a DMX splitter and termination plug.

i have had first hand issues with running xlr mic cable's. i ran into delay times and the 4th adj accu spot 250ii head would erradically just do its own thing sometimes. all brand new accu cable dmx cables and a dmx terminator fixed that

then i decided to add a bunch of led color strips.....well.....things go funny again but only on the color strips....

so i bought a dmx splitter box (other brand not named as this is an adj site) and it isolates each channel from each other and from the input, gives each channel proper voltage. BAM put the led strips on channel output 2 and adj moving heads on channel 1....things work perfect.

i have now added 2 adj galaxian sky lasers as of today and will be testing them out live this thursday night, saturday night, the following friday and saturday also.

heck i also added a neo neon 250mw animation laser (yes its usa legal and i am waiting for my fda license to come in)

i think since my dmx splitter has thru outputs that are seperate from the 4 dmx output channels, i might buy another dmx splitter since it can be done this way.

Remember, as soon as you throw a mic XLR into your DMX chain, anything after that will be affected.

Serra Ava has recommended(on here but in another thread) no runs of more than 32 fixtures. While I have enough stuff to be able to do exceed that recommendation, it's not something I want to take a chance on. I just don't like running the signal through that many fixtures.

In regards to using a splitter/repeater chained to another splitter/repeater, the general concensus seems to be that there's no harm in doing that. I'm debating this myself because on most stages I have to run, having an additional split near the stage would clean up wiring a lot.

For example, in my main show, I have a run that goes to a tree of lights with 2 color changers and 4 LED cans, then they go on a 75 foot run to a follow spot.
I have another run that goes across the floor to 4 mega panels, then off another 40 feet to another tree like the first, then another run back to a follow spot.
A third run goes to the stage. This run has to go to backstage center rear to 2 foggers(hazer and ground fog), then to the producer's fogger, then up to a mover, across 4 LED Mega Bar 50's, a UV LED can, a dimmer pack and then a mover.

I still have a run open. But what if I wanted to hang lights front and back stage? The splitter is near me at FOH.

The nice thing about DMX is that it's fairly robust. There are simple things we can add to improve reliability and performance that don't cost much. DMX cables don't really cost more than XLR cables.(and DO mark your DMX cables so you don't confuse them, or mark your XLR, whatever you want, I put white electrical tape on BOTH connectors of my DMX cables). And you SHOULD be using DMX cable, not XLR. Adding something like a splitter/repeater does add cost, but you have to lok at what you get for the money. For me, the splitter was a great purchase and I'm in need/want of another.

DMX has shown it can grow with users. This is somehting that most short-sighted technologies developed these days don't all take into consideration.