DMX512 stands for...

[lieperjp]

What does DMX stand for? Does it stand for anything?

When doing research, I came across two ideas:

1) It doesn't stand for anything.
2) It used to be Digital Media Effects, but no longer carries that meaning.

I doubt the accuracy of number two, but it was the only definition that made sense.

[cdub260]

If I remember correctly, it stands for Digital Multiplexing. I believe AMX was Analogue Multiplexing.

[waynehoskins]

Digital Multiplex. 512 is the number of usable addresses in the serial stream.

AMX192 is, of course, analog multiplex with 192 samples per frame (though perhaps in the CD80 days it sometimes had only 96, from what I infer).

DMX512 is largely based on old Colortran Protocol, which was renamed "CMX" following the popular convention. AMX192 is a formalized Strand CD80 Protocol.

And then there's the other proprietary Mux protocols. D54, K96, LMX, and so on.

[derekleffew]

Originally Posted by lieperjp

What does DMX stand for? Does it stand for anything?

This information is clearly presented in our glossary, and thus, if it weren't currently down due to an upgrade, you'd be in serious trouble for not checking there first, mister.

[philhaney]

Originally Posted by waynehoskins

Digital Multiplex. 512 is the number of usable addresses in the serial stream.

It's a binary thing.

Originally Posted by waynehoskins

DMX512 is largely based on old Colortran Protocol...

I worked at Colortran back in 1987 - 1989. I can remember our protocol wich, now that you mention it, is a lot like DMX512.

I can also remember (embarassingly) thinking, "DMX is a fad. It'll never catch on."

(If I remember correctly, we had a break and then the data came down the line like DMX starting with channel 1 and counting up. Another break signified stop, we're starting over, and the data would come again. DMX inserts start and stop bits in there for each channel. If I'm not getting this right, someone please correct me.)

[waynehoskins]

Originally Posted by philhaney

(If I remember correctly, we had a break and then the data came down the line like DMX starting with channel 1 and counting up. Another break signified stop, we're starting over, and the data would come again. DMX inserts start and stop bits in there for each channel. If I'm not getting this right, someone please correct me.)

I think you're right, DMX512 has start and stop bits, and then a long frame break.

I've had to figure out this whole basic thing in a side project I'm tinkering with, of multiplexing a bunch of camera tally lines onto a one-wire bus. Since I have only one bit per address, I'm going to interleave short-width clock and long-width data, borrowing an idea from NTSC and making the clock be a negative pulse (easier to discriminate at the receiver); and then a long frame break. Funny how all of these mux systems end up being the same basic animal...

[derekleffew]

Originally Posted by philhaney

...I worked at Colortran back in 1987 - 1989...

So YOU'RE the one who built my Prestiges (right now I can think of five, without trying too hard) and D192 dimmers. I've been looking for you....

The early history of USITT DMX512 is well-documented in the book, The Speed of Light, by Linda Essig. I suggest everyone read it, so we can stop having these conversations.

[waynehoskins]

Originally Posted by derekleffew

So YOU'RE the one who built my Prestiges (right now I can think of five, without trying too hard) and D192 dimmers. I've been looking for you....

Hey, that's better than being the guy at Alt who decided the KL line was a good idea.

[lieperjp]

Originally Posted by derekleffew

This information is clearly presented in our glossary, and thus, if it weren't currently down due to an upgrade, you'd be in serious trouble for not checking there first, mister.

I looked once upon a time, but I don't remember it saying anything about the what it stands for. Plus, it's a major part of theatre history... so a good use for the theatre history forum!!! Which is a cool idea.

Is this supposed to be common knowledge or something? I also looked at, oh, maybe twenty or so different websites and nothing was found. Maybe a Wikipedia edit is in order?

[propmonkey]

pretty much every book or website that ive checked out in lighting and lighting history mentions dmx as digital multiplex. what sites did you look at?