Can a 4 Port Passive Hub be used for DMX

[TexasStingray]

If I understand how the 4 Port Passive Hub works, that is 3 wires for +12Volts, 3 wires for Negative, 2 wires for the Pixelnet. If I use DMX instead of Pixelnet, Can it power a DMX Dumb String Controller as well? This might be a question for RJ.

Thanks
Scott Wanner

[tbone321]

It really depends on what you are talking about.  If you are talking about the Lynks dumb string controller, that is not DMX.  It is a pixlenet controller just like the smart string controller and will work with the 4 port passive hub.  If you are talking about someone elses device, I wouldn't recommend using it for that.  The passive splitter can possibly cause signal issues with DMX and uses 3 pairs of power for a reason.  If you are only using one pair the cable or connector may fail and you are limited to 4A this way.  If yo have DMX dumb string controllers from someone else, I would use an active DMX splitter and run the power to them seperatly. 

[TexasStingray]

I created by own Dumb String Controller that uses DMX. I see that 4 port pasive hub has a 12volts input. I thought it could power my controller and send DMX instead of Pixelnet.

[chrisatpsu]

in the pure sense of the splitting...  i know the dmx splitter regenerates the signal.  I don't know what the issue of splitting the signal without regenerating, although there might me a thread that talks about it. something tells me b/c of wiring lengths, and since it's your own design, it might be a YMMV or try it and see kind of moment.

[n1ist]

Technically, no.  Practically, yes. 

The 4-port passive hub simply takes the RS485 data pair from the input connector and connects it in parallel to the 4 output connectors.  It then takes the 12V power from the green connector and connects that to the 4 output connectors.

Technically, using this on DMX could cause reflections on the signal that may cause erattic operation and flicker.  In reality, however, for the length of runs we usually use, it will likely work fine.  I would try to keep the output cables short and of similar length, but that probably wouldn't matter much.

As for the general idea of injecting power over the same cable that has DMX, that's fine; it is commonly done for color scrollers, gobo rotators, irises, and the like in the theatrical world.

A true DMX spitter, like Chris says, regenerates each output independantly.
/mike

[rm357]

If you are thinking holiday coro style, be warned that we are wired differently.

Lynx wires 3,4,5 =+12, 6,7,8 =gnd
Holiday coro solids=12v, stripes = gnd (I think that's 3,5,7 = 12v, 4,6,8 = gnd)

[tbone321]

I created by own Dumb String Controller that uses DMX. I see that 4 port pasive hub has a 12volts input. I thought it could power my controller and send DMX instead of Pixelnet.

Well if you designed it, then you might have some luck in making it work since you can configure the input to match that of the passive hub.  Just remember that the passive hub has the same 4A per output limit that the active hub has and it doesn't have any termination capability so unless your MX controllers do, you could have some signal reflection issues.