DMX Questions from a newbie

[LightParts]

Recall as well that the manufactures had the option to implement talkback from device to console, using the spare pair of wires in the 5 pin XLR, just nobody bothered. 2

At the time DMX was released, Vari Lite held a patent on bi directional communication to a lighting fixture. As Vari Lite successfully sued some potential competitors out of business, bi directional communication was avoided for a long time. In fact, when VL sued High End for patent infringement, they cited the single checksum byte sent after a software upload to a fixture as "bi directional communication".

 

[Chris Pflieger]

At the time DMX was released, Vari Lite held a patent on bi directional communication to a lighting fixture. As Vari Lite successfully sued some potential competitors out of business, bi directional communication was avoided for a long time. In fact, when VL sued High End for patent infringement, they cited the single checksum byte sent after a software upload to a fixture as "bi directional communication".

That's the most asinine patent I've read about in... well, months, anyways.

There's absolutely nothing new or innovative or something that couldn't be thought up in about ten minutes.

 

[LightParts]

That's the most asinine patent I've read about in... well, months, anyways.

There's absolutely nothing new or innovative or something that couldn't be thought up in about ten minutes.

Agreed. But back then, it was *somewhat* novel.

The patent system is very broken. There are more patents being filed for and granted than examiners would ever have the time to study closely.

All a patent is good for is a license to sue someone for infringing. If a patent holder doesn't have the resources to defend, their patent is toilet paper. The best way to have success with any product is to come up with something that has terrific utility and a price people can't say no to, and be one of the first to release it.

 

[Jay Ashworth]

"RDM uses the space *between* the DMX packets"?

I thought it used the *other pair* in the 5-wire DMX cable.

 

[coldnorth57]

no RDM uses the same data lines a DMX that is why 3 pin DMX still works for both.

 

[Chris Pflieger]

Agreed. But back then, it was *somewhat* novel.

Bidirectional communications was common. It didn't take a genius to think that maybe it'd be useful if light fixtures did that.

My boss came to talk to me about patenting a mundane switch I'm working on... I had to just bite my tongue and sit on my hands...

 

[BillConnerFASTC]

I'm not professing any DMX expertise, but aren't the two other pins used by some manufacturers for other purposes - like power? Or have been? Seemed like that was a part of the reason for 5 pins - other than just not being same as mics - but @STEVETERRY is probably as well positioned as anyone on that history.

 

[icewolf08]

I'm not professing any DMX expertise, but aren't the two other pins used by some manufacturers for other purposes - like power? Or have been? Seemed like that was a part of the reason for 5 pins - other than just not being same as mics - but @STEVETERRY is probably as well positioned as anyone on that history.

Any use of pins 4&5 is not compliant with current DMX specification. There are a few devices on the market that allow you to run a second universe on the extra pair (essentially just a break-in/break-out box on either end), I don't know of anyone running power on it, and that seems like a terrible idea. The spec still has the second pair as reserved for future use.

 

[coldnorth57]

On 5 pin I have only ever heard of DMX and RDM all running on the same 3 pins....and the other 2 not being used. But 4 pin have DMX and power on these four pins

 

[Mac Hosehead]

I don't know of anyone running power on it, and that seems like a terrible idea.

For a while Clay Paky was putting a supply voltage on pin 5 and it was a terrible idea.

 

[dbaxter]

My understanding was the 5 pin connector was strictly to avoid confusion between DMX cables and 4 pin scroller cables and 3 pin audio cables. We all know how well it's working keeping audio cable from being used as DMX cable nowadays.