Segregating DMX

Dear Swami,
I've heard people say that you should separate fixture types on their own DMX line or they will not work properly. Is that true?
Signed,
Lines Crossed in Dimmer Land
Dear Crossed,

The sky is dotted with clouds that color truth. DMX is well defined and as long as the maker of the machine follows the path of the protocol it will take flight. There is no technical reason for segregating DMX fixtures by type, although there may be historical reasons. In the early days of automated lighting, Martin used an non-compliant pinout and swapped pins 2 and 3. If you used an adaptor it would work with any other DMX devices. Old habits are like the weeds that grow between the cracks in the sidewalk. To be rid of them is hard. There may be other reasons for the practice of segregating DMX by fixture type but it has nothing to do with compliant fixtures.

Comments

  1. UnknownApril 5, 2015 at 12:25 AM

    Quite a lot of touring production companies put each type of fixture / lighting bar on their own DMX universe. I think this is more to do with making the design easier to follow and makes it easier to recall and program a large rig?

    I've had instances where lights (generic Chinese and ETC LEDs) will only work properly (without random flicker) if a DMX splitter is put straight after the output of the desk. All cabling checked out OK and my Swisson DMX tester showed exactly the same refresh rate and timings coming directly from the desk and the splitter. Maybe the splitter is optically isolating better than the desk, which also has opto isolation. Even that doesn't make sense because I put the desk on the same power circuit as the fixtures and the flicker was still there.

    DMX is quite simple but sometimes things are a bit more involved, even with a simple rig, experience and some test gear.

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