DMX termination

[Iyatech]

Hi Everyone

 

New to LED fixtures (at a school that still ran Rank Strand rig and conventionals for years!)

 

Do the Chauvet Rogue range (in particular R1 spots and washes) auto-terminate a DMX line, do I have to plug in terminators, or is there a setting in the setup to terminate the unit if last in line?

 

Regards

 

Ivor

[timsabre]

Do the Chauvet Rogue range (in particular R1 spots and washes) auto-terminate a DMX line, do I have to plug in terminators, or is there a setting in the setup to terminate the unit if last in line?

 

They don't auto terminate, or have a setting, but in a small rig like a school you will be fine without a terminator.

 

If you get weird flickery issues then that is time to start putting terminators on, but this normally only happens when people start doing dodgy things like y-splitting the cable, or there are vast lengths of cable involved.

[csg]

whilst I still have a couple of terminator plugs floating round in my large tool case, the days of needing to terminate every DMX line are long gone, I've haven't needed to terminate a line in years, and deal with 1000's of different data lines every year. Don't worry about it unless you have a problem, and even then the likelihood of it being caused by a reflection are remote.

[Jivemaster]

Careful soldering, and adequate connectors will solve most DMX problems. Just occasionally a terminator is needed -you should own a couple. Having well made crossover plugs for the few remaining "Polarity reversed" DMX appliances (typically OLD Martin stuff) may help.

[Iyatech]

Thanks for the replies

 

I WAS having "odd" effects, but I now know it wasn't as a result of non-termination.

And didn't realise that termination was a "thing of the past"

Call me "old school" :-)

 

Thanks again

[sleah]

(at a school that still ran Rank Strand rig and conventionals for years!)

 

Shocking! How very dare they! ** laughs out loud ** :P ;)

 

It's worth making sure all XLR plugs'n'sockets are clean. I've had flickery issues where the contacts had become tarnished. :(

[Tomo]

Oh FFS.

 

Termination is not a thing of the past and it is HIGHLY recommended to do so.

 

Please stop recommending bad practice just because you'll usually "get away with it".

You'll almost always "get away" without a harness in a cherry picker, but that doesn't mean you shouldn't bother wearing one!

 

Aside from reflections (which become an issue above about 20-30m), fitting a terminator also finds your broken cable during rigging, instead of later on during the actual show.

[James Remo]

I've never heard of anyone dying from an unterminated DMX line... Straw man? I have, like Chris, ran many thousands of DMX lines unterminated with few problems. I still carry terminators in my tool box but do not terminate as a matter of course.

[indyld]

The handy thing about DMX line termination is it often exposes dodgy connections, dry joints and generally bad signal by breaking the DMX signal line completely. If the whole kaboodle stops working once a terminator is included, there is definitely a problem and one that may have gone unnoticed until things start twitching during the show.

[Tomo]

I've never heard of anyone dying from an unterminated DMX line... Straw man? I have, like Chris, ran many thousands of DMX lines unterminated with few problems. I still carry terminators in my tool box but do not terminate as a matter of course.

Nah, Hyperbole!

DMX is not permitted to be used for dangerous devices, so the worst-case consequence is that somebody gets fired (or not re-hired).

 

As you said, you have indeed encountered problems.

It is likely that many of those problems you encountered would have never occurred, or would have been detected before the show if the line had been terminated.

 

Best practice doesn't mean it'll never work if you don't, but that it'll be more reliable if you do.

 

DMX-controlled tungsten and moving lights are very tolerant of bad signals, as their physical nature tends to smooth over many momentary glitches.

- If this packet is wrong, the next one will put the level back in <30ms.

 

LED is much less tolerant - an LED fixture really can flash to full and back in the 25-30ms between packets.

 

A good book that I'd recommend for everyone who works with DMX:

"Recommended Practice for DMX512: A guide for users and installers" by Adam Bennette.

 

The PDF is currently free from this site: http://tsp.esta.org/tsp/documents/published_docs.php

(Scroll to the bottom)

[Shez]

How common or otherwise is it for fixtures to have the facility to either auto- or be manually set to terminate without needing a physical plug? It's vanishingly rare that I see terminators in the wild - when plugging up looms along trusses for touring shows that come through my venues, the last fixture in the line virtually never has anything connected to its "out".

[timsabre]

How common or otherwise is it for fixtures to have the facility to either auto- or be manually set to terminate without needing a physical plug? It's vanishingly rare that I see terminators in the wild - when plugging up looms along trusses for touring shows that come through my venues, the last fixture in the line virtually never has anything connected to its "out".

 

It's not common, at least in my experience. You sometimes see it as a dipswitch option but even then people tend not to use it. I suspect a lot of the time people incorrectly think the fixture is auto terminating because it works without a terminating plug, but it needs a special XLR with a switch built in which is unusual.

 

I think because it just works without 99% of the time, people don't generally bother, and just address the problem if there is one. Of course if it starts in the middle of the show then you're knackered but problems usually show up before that.

[Tomo]

Automatic self-terminating is quite common in 'upper end' fixtures, but is very rare in the mid and lower end.

 

As Tim said, it uses a female XLR-5 with a built-in microswitch, which obviously costs a bit more than the standard one.

 

Almost all DMX equipment intended for permanent installation (dimmer packs, wallmount/DIN rail devices etc) has a dipswitch or similar for termination as that costs practically nothing.

[timsabre]

Automatic self-terminating is quite common in 'upper end' fixtures, but is very rare in the mid and lower end.

 

I'm not sure, even some stuff I would class as "upper end" doesn't do it. You will no doubt be able to say what ETC are doing, but I'm fairly sure even the most expensive Clay Paky, Robe or Martin fixtures don't have auto termination. (just to pick on a few common brands)

 

As you say it is probably a lot more common in fixed installations to do termination properly. I've never seen anyone bother on touring or event rigs.

[johnhuson]

I'm sure that most of us that have been in this industry for a number of years know that terminating DMX lines is 'best practice' but I'm confident in saying that it is far from the usual practice these days.

 

Agreed terminators can highlight cabling issues which may have reared their head during the show, but at the same time a terminator doesn't prevent issues happening during a show. Hand on heart (and I'll probably regret saying this) I've not used a DMX terminator in a temporary installation for getting on 20 years and I've NEVER had a DMX issue that has suddenly appeared during a show and I can't remember a time that it's happened before hand.

 

We're not alone, I would wager that 99.9999999% of major tours/events going on right now aren't using termination.

 

With regard to self terminating fixtures, we own Robe, Martin and Aytron fixtures of all whom I would class in the 'upper end' of fixtures and none of them self terminate.

 

All qudos to ETC if they're producing fixtures which do this but again I think they're in the minority.

 

Not saying any of the above is what should be done but it's whats happening in reality.