Control/Dimming Pulling DMX from 4 Pin lines

Hello,

I saw similar posts here but not quite the answer I was looking for so I thought I would ask.

I want to pull just the DMX signal from power supplies or 4 pin scroller runs. A 4 pin XLR tying the + and - data signals to the appropriate pins on a 5 pin XLR makes sense but where should the shield of pin 1 on the 5 pin end connect on the 4 pin end? It seems like it could go to the shell or to pin 1 of the 4 pin end.

Thank you.
 
Hello,

I saw similar posts here but not quite the answer I was looking for so I thought I would ask.

I want to pull just the DMX signal from power supplies or 4 pin scroller runs. A 4 pin XLR tying the + and - data signals to the appropriate pins on a 5 pin XLR makes sense but where should the shield of pin 1 on the 5 pin end connect on the 4 pin end? It seems like it could go to the shell or to pin 1 of the 4 pin end.

Thank you.
I don't believe it's DMX coming out of those 4-pin cables - DMX feeds the power supply unit, but it then feeds its own proprietary protocol to scrollers. As I understand it at least..
 
You need to check the brand and the protocol. Irked is correct not all scrollers use DMX as a control protocol. That beings said:
dmx colorscroller.JPG


"If you use this and fry something down the line, Yadda, Yadda, Yadda"
 
I don't believe it's DMX coming out of those 4-pin cables - DMX feeds the power supply unit, but it then feeds its own proprietary protocol to scrollers. As I understand it at least..
In a few cases, it may be a proprietary signal coming out, but in most cases it is just plain old DMX coming out of the supplies. This is definitely the case for Apollo and most (all?) of Wybron. There should be no issue with pulling the dmx out of a 4-pin. Just.... What Van just posted above.

This was recently discussed not too long ago. Some searching should bring it but.
 
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Some gear (specific brands elude me off the top of my head) use pins 1 and 4 for an electrical circuit, and the shield is dropped from the data end of things. It means the DMX isn't really DMX any more, as the data+ and data- make do with a sort of floating reference for the units - it's typically not an issue for the comparatively short runs seen with scrollers from their PSUs, at least for the scrollers in question - but you could run into gremlins downstream with other gear listening to the scroller data and a bad ground reference. I'd avoid it if at all possible. The cost of repairing gear you might inadvertently damage could easily far outweigh the cost of an opti and an actual data line.
 
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All things considered, it is very bad practice to make an adapter to get DMX from a 4-pin accessory chain. Most 4-pin accessories are designed to run in a loop topology (the only one I can think of that doesn't is Wybron RAM devices), meaning that the last unit in the chain should be connected back to the power supply. This provides both DMX termination as well as helps to maintain proper voltage and current on the DC bus. Breaking out from a device on the chain will ultimately defeat one if not both of those ideas. For all the work of researching and building adapters, you would probably save yourself a lot by just picking up a length of DMX cable and using the DMX-thru port on the power supply!
 

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