DMX Splitter with dimmer racks

[Richie Love]

Hi guys

Having a bit of a brain fart at the moment, I'm doing a show in a small venue and there's only one DMX output from the desk to the dimmer racks, can I use a splitter between the desk and the rack to add led fixtures? I.E Console -- splitter -- led fixtures -- dimmer rack

 

 

If this makes sense?

Cheers

[kitlane]

Hi guys

Having a bit of a brain fart at the moment, I'm doing a show in a small venue and there's only one DMX output from the desk to the dimmer racks, can I use a splitter between the desk and the rack to add led fixtures? I.E Console -- splitter -- led fixtures -- dimmer rack

 

 

If this makes sense?

Cheers

 

Yes, that is the main job of a splitter. Alternatively, there might be a DMX Output on the last dimmer rack that you can daisy chain to your LED fixtures. The official limit is 32 devices per DMX output. This can be increased using a splitter.

[timsabre]

Just to be clear "a splitter" is not a y-split cable but a proper powered box which buffers each DMX output.

Splitting DMX using a y-split cable is generally frowned upon in polite society.

I'm sure you knew that...

[norty303]

Splitting DMX using a y-split cable is generally frowned upon in polite society

 

But might just get you out of a hole in the gutter ;)

[timsabre]

Splitting DMX using a y-split cable is generally frowned upon in polite society

 

But might just get you out of a hole in the gutter ;)

 

Indeed. Usually works quite well but don't tell anyone you did it. Also likely to cause bizarre control failure at some vital moment.

[the kid]

Hi guys

Having a bit of a brain fart at the moment, I'm doing a show in a small venue and there's only one DMX output from the desk to the dimmer racks, can I use a splitter between the desk and the rack to add led fixtures? I.E Console -- splitter -- led fixtures -- dimmer rack

 

 

If this makes sense?

Cheers

 

Yes, that is the main job of a splitter. Alternatively, there might be a DMX Output on the last dimmer rack that you can daisy chain to your LED fixtures. The official limit is 32 devices per DMX output. This can be increased using a splitter.

it can ?!

 

I was under the impression that a spliter was a unit and everything off it was a unit. Even if leg 1 had 29, leg 2 had 1, you would have the splitter and the desk being 1 unit each, and that makes your 32

[timsabre]

I was under the impression that a spliter was a unit and everything off it was a unit. Even if leg 1 had 29, leg 2 had 1, you would have the splitter and the desk being 1 unit each, and that makes your 32

 

Every line off a splitter is a new line so you can just keep on adding lines of 32.

However, the 32 limit is completely irrelevant these days as line drivers hardly draw any current.

Using splitters is more a case of allowing more convenient wiring rather than having one massive daisychain which is often difficult to accomplish.

[the kid]

So in theory you can split, split, split?

[timsabre]

So in theory you can split, split, split?

 

Yes you can. Splitters off splitters if you like.

Obviously you only have 512 channels on the DMX cable so unless you are pairing up lots of stuff, there is a limit to how useful this is.

 

In "the olden days" each device drew some current off the DMX line so there was a limit of 32 devices, as the driver in the console could not be relied upon to operate more than that. When you introduce a splitter each output line has its own driver so could drive another 32 devices.

In these times of micropower, you can hang hundreds of devices off a line before the driver starts having trouble, but a splitter is a good idea to make it easier to wire stuff up and for fault tolerance (fault in one run of DMX will not affect the others).

[Richie Love]

Cheers guys that's cleared a lot up for me

[Jivemaster]

Active isolated splitters are essential! Especially if there any kit that doesn't do DMX correctly. I suspect we've all had a single piece of essential kit that sometimes mangles DMX through.

[Guest]

Like the others have said, 32 units is the advised maximum for one daisy chain without being re-powered again (by a powered buffer).

Make sure you terminate your data at the end of each daisy chain, even though from experience I haven't yet found any difference between whether I do terminate data or not with a 120 ohm resistor across pins 2 and 3!

For your scenario then I would go Desk ->Buffer -> Dimmer ->Terminator

and also out another output of the buffer -> LED intelligent fixtures -> Terminator

 

Edward

[timsabre]

A terminator will often show up dodgy connections in the DMX. If one of the 3 DMX lines is broken it will probably continue to work but unreliably. The terminator will stop it working and show you that there is a problem.