Re: DMX daisy Chaining (was space conversion estimate)

T-bird Leader Eric N Johnson radioed the tower, on 2/24/2006 1:10 PM:

Ron Killmer <killjay@xxxxxxxxx> wrote:
Remember that DMX can only daisy chain 8 fixture, so plan for Opto-isolated hubs to breakout the DMX distribution to all of your hanging areas.

You can chain a lot more than 8 fixtures on a DMX line. RS485 allows for
32 "unit loads", and there are 1/8 unit load line interfaces out there,
which would hypothetically allow up to 256 devices.

Practically, it's a bad idea to get too many fixtures on a segment because a
single fault or loose cable can cause the entire segment to fail.
The exact number depends on circumstances, but it's more than 8.

Still, you're definately right that well design DMX distribution
is an asset in a space. I'd also build a significant CAT5/Ethernet
infrastructure into any new space.

Eric


I admit I am not well up on DMX yet, as it's just coming into the venue I work in. Some of my reading on numbers of units may be specific to certain assessories and not to the lighting fixtures.

Actually I was alluding to the 1/8 breakouts as the means to talk to lots of equipment with a minimal risk of disturbing the purity of the DMX signals. Impedances and resistances could distort signal quality and timings.

Good point about the CAT5 for Ethernet. Another good to build in is a network for the remote focus unit if the one for the console is wired, not wireless.
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