"Tapping out" DMX out of a scroller line

[HobitLight]

Hi guys. Someone I know has made some 4-3 and 4-5 pin XLR adaptors for coming out of a scroller and going into another DMX device. The pinout is basically normal DMX (screen, data +, data -) but dropping the +24v. The main reason this is used is because he has built his own scroller PSUs which have several outputs, so uses these adaptors so that the PSU can be used as a DMX splitter if need be. This works fine, and I don't want to get into the ethics of whether or not this is good practise or not!

 

My question is about effectively "tapping out" DMX halfway through a scroller line. On more than one ocassion I have had several scrollers on a bar with other DMX fixtures on the bar too. It's not really much of an issue, but I obviously have to run a second DMX line along the bar to deal with them. I suppose this is more of a theoretical question, but is it possible to make a lead that will take DMX out of a scroller line, and put it back in once it has gone into another fixture? The wiring I have in mind is that there is a male 4pin XLR wired to a female 5pin XLR and vice versa. These would be placed between two scrollers so that the DMX can go to the fixtures and then back into the scroller line. To send the +24v across to the next scroller, there would be a single core cable between the two four pin connectors so that the power is still taken to the next scroller.

 

I feel I've not explained this correctly so have made a diagram seen here.

 

Would the above work and would this be fine to use if there was ever a need for it?

 

Thanks in advanced!

[Ynot]

Well, I for one wouldn't feel comfortable with this, and to be perfectly honest don't see the point.

We have DMX cables and we have scroller cables. Running the two alongside on a single barrel doesn't seem too heinous to me, even with a large number of fixtures.

But using these adaptors is likely to make fault finding trickier IMHO.

 

These home-brew PSUs - there is a pukka isolating DMX splitter built in, yes?

[maeterlinck]

Nothing to do with this I assume?

 

Nothing wrong in principal. It's not accepted practice though. Also by the time you've bought the additional connectors etc, you could easily have got a long DMX cable which would probably be more universally useful.

[dbuckley]

Its the kind of trick you can do on your own rig but you wouldn't do it in the presence of other professionals.

[Ben Lawrance]

If you drop the +24v from pin 4 of the scroller side, how will you get it back again for the next scroller?

 

If you tap the DMX from the last scroller, it could work, but as others have said, it's very unprofessional.

[LXbydesign]

No , its not viable.

 

Yes it would work, but with all those extra jumpers and seperate 24v lines flying around its very messy , could cause a headache fault finding and could also cause damage equipment if someone is up on the rig re plugging stuff who deosent know what your set up is.

 

DMX and scroller cable is seperate for a reason!! Dont go against lighting 'nature' and fiddle with it. How hard is it just to throw in another lead for DMX?

 

or another way would be if you have a lot of fixtures on a bar as well as scrollers, why not locate the scroller PSU on the bar as well!! That way u have a DMX in / out up there for easy plugging up!