Confusing Myself on DMX and Channels

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Sep 26, 2019
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I'm not sure if it is because I have had way too much time to think about this with the Rona hiatus happening, but realize that I don't really know the answer to the following and have come to over think it , but...
I was thinking about patching/programming DMX, particularly on the ETC Express and Ion. How is it that the Express has 250 channels but 1024 DMX outputs? How is it the Ion can assign 1 channel to a multi-dmx channel light fixture, but Express needs a channel per DMX function? Meaning aren't the 1024 outputs pointless on the Express if there are only 250 channels? Is it the advancement technology? Was I or am I doing it wrong or was/is there a feature I am not aware of?
 

josh88

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The express was pretty limited in that sense. The Ion is new enough/smart enough that it can see or be told what a fixture is and you get some bonus control of parameters and is doing some of that work under the surface through the color picker, etc. The Express was never really made for movers or LEDs, so it doesnt have a system to show or process all of those parameters and ends up needing more channels to control each one because of that.

The Element (technically the upgrade to the express) handles that better because the OS was updated and control had changed by the time it came out. Then the ION is specifically geared more towards movers even more then the element. The express loves living in an analogue world with conventional lights or maybe scrollers or accessories like icues, or sea changers, 30 channel fixtures burn through it's capability real fast.
 

MNicolai

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These days, essentially it goes like this.

Channels are a control group. They can contain multiple outputs.

Outputs, aka Parameters, aka DMX addresses, are specific functions of specific fixtures that you want to control.

In terms of postal speak, a channel is a zip code that categorizes a specific neighborhood or city. An Output is a street address that tells you a very specific location within that zip code.

At the time of Express, it was common to double up outputs (generally dimmers) into the same channel. You might have 10-20 dimmers for your cyc lights but only 3 colors -- so you would patch 10-20 outputs to 3 channels. You don't really need control of every cell of every cyc light. That's a little less common now because we've largely gone away from dimmers and and now consoles with higher channel counts, but even things like house lights -- you might have 40-50 dimmers ("outputs") of house lights but functionally you only need 5-6 channels of control. Probably something like 1) Main House Lighting, 2) Aisle Lighting, 3) Stage Works, 4) Wall Sconces, 5) Backstage Blue Lights, etc..

The vast majority of people with Express consoles only ever used dimmers, so it wasn't a big deal that DMX fixtures needed multiple channels. If you were doing lots of DMX fixtures you were probably on an Obsession or Obession II which had a better user interface for working with fixture parameters and the control processors had more options for the number of channels. As Ion/Eos/etc were coming to market, DMX fixtures were much more popular and a decision was made out of simplicity to make channels just mean "Control Channels" and call it a day. Especially since even the simplest of DMX fixtures today might have 20-30 parameters if you get into 16 bit parameters. So it would really suck to buy a console with "250 channels" today and find you can only run like 20 fixtures on it. Much easier for people to understand that generally, 250 channels means 250 fixtures, with an upper limit of 1024 outputs if you're on say an Element 250.
 

MNicolai

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By the way, the evolution of Express into Eos/Ion is like when Pluto lost it's classification as a planet. Nothing changed really about Pluto, but the nomenclature had to catch up to our modern day understanding of the world around us. The definition of a "planet" hadn't been updated since ancient Greece so it was time to bring that terminology into line with what we now know about astrophysics. Obviously jumping out of Express into Eos/Ion, features like "Moving Lights" have come to mean all kinds of multi-parameter DMX fixtures that have no pan/tilt operations. A change was needed. Hopefully ETC didn't suffer any letter-writing campaigns of people furious about the updates -- though there was certainty industry-wide anxiety when ETC announced the end of the Express series.

 

MRW Lights

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To be fair.... the idea of "multi parameter channels" existed long before the EOS family... Some of us thought we were the bees knees programming technobeam "fixture profiles" on the expression..... and before that there was the mystical serial port on the microvision and the secrets it might have one day unlocked... which thankfully was before my time. Since we're primarily discussing ETC here I've only heard mystical tales of the famed Mega Cue and sometimes day dream in tech about what we've lost or gained in the power of a name from MEGA CUE! to the futuristic ION-XE / Gio ... I sincerely believe Fred Foster never lost that passion from the idea that inspired the Megacue to the ideas he continues to inspire today through his legacy.
 

RonHebbard

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I agree, Bill. I can remember sitting on a stool and running dimmers with both hands and both feet with my shoes off.
Or as one of seven operators standing in a mid-city alley behind Toronto's Royal Alexandra between two rows of seven resistance boards SWEATING while listening to the summer rain pitter-pattering on the thin, translucent, plastic sheets carefully supported o'er head, thoughtfully angled so the rain fell away from the theatre rather than into it.

This would've been 1968 or '69; don't ask me the name of the touring production, all I recall is a Broadway musical on an international (US and Canada) tour.

Unlike @JonCarter , we kept our running shoes on to serve as soggy insulators while standing in the puddles.
No rain fell directly within the plastic, although the high humidity resulted in steam rising from the 6K's.
Toronto's IA 58 had more productions than they could staff and were scrambling for warm bodies thus they phoned Hamilton's IA129 who contributed me to the melee.
Toodleoo!
Ron Hebbard
 

Jaixom

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I'm still using an Express 72/144 in my school's Drama Studio. Had the budget AND the approval this year to finally upgrade and have ordered an Ion XE 20, two fader wings, and two Dell touch-screens. My training/thought processes are all geared towards old school lighting presets etc... so I'm going to be spending the summer learning the board and updating my knowledge. Oh and creating magic sheets that the Drama teachers and students can easily use. We're still pretty much a conventional lighting rig... but I've also ordered 4 Altman AP-150s to play around with.
 

geoffrey hugh

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I think board ops were in better physical condition - less overweight - when it was all resistance plates and auto-transformers.
And that better physical conditioning came from not just theatrical labour.

In 1976 I was HE on the tour of Equus out of New York. My gear came from BASH stage lighting in Bergen NJ and Masque Sound on 48th (?) Street in the city.

During a phase of one nighters I had to do laundry. I used the theatre machines, but could not use the dryers so, I hung everything from the cables descending from 8 electrics pipes to my two piano boards which had 4 auxiliaries (double throws and presets) placed on top. It got really hot in there. My clothes were dry before the show was over.

There is a well known photo of that setup, a B&W taken by the SM, released as a view of cool, backstage life.

I do not have a copy but would love to have one. If anybody comes across it, please consider posting.

The photo is reminiscent of a NY fire escape covered in hanging, drying clothes.
 
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I think board ops were in better physical condition - less overweight - when it was all resistance plates and auto-transformers.
My first design job was for the East River Players at the Afro American Theatre located in the Martinique Theatre at Greeley Square in NYC. This was the summer of 1974 and I was a college sophomore. The theatre had two resistance boards at 90 degrees to each other and a small auto transformer. I’d set a light cue and ask, can you do it? My amazing technician would say, Wait a minute, wait a minute , I think I ...can , yeah I can do it . I heard later that the actors not onstage always went to watch him work, reporting that he did indeed use a broom across multiple dimmers (no interlock), his other hand and a foot to pull off some cues!