DMX A & B on a tour pack, and Why some DMX 3 pin and others 5 pin?

[121 Gigawatts]

DMX A & B - looking at a touring pack with many channels, why is there a DMX A & B? Also some of my DMX mostly LEDs and low wattage dimmer packs are 3-pin DMX, but some boards and other larger wattage dimmer packs are 5 pin? I gotta find adaptors now...

 

[brucek]

The 3 pin vs 5 pin is a matter of 5pin is the DMX512 standard....and 3 pin is the its-a-cheaper-connector-and-i-can-get-away-using-mic-cable(which is not 150ohms but usally works anyway)

 

[RonaldBeal]

The A&B inputs let you merge, do houselights or failover. Imagine a 96 way dimmer pack with 72 dimmers as the lighting rig and 24 as the house lights, fed from two different controllers etc.
As for the 3-pin vs 5-pin. 5 pin is the actual standard and is found on most pro gear. 3 pin was done on low end budget gear so folks could use microphone cables (even though 3 pin data is different from 3 pin microphone cable.)

 

[derekleffew]

I gotta find adaptors now...

Yes, but the good news is they are easy to build oneself and almost always work fine. I can think of no instance where a properly made adapter, 5-3 or adapter, 3-5 did not work.
Just wire both ends pin to pin: pin1=pin1, 2=2, 3=3. Leave pins 4&5 unwired on the XLR5.

 

[techieman33]

Yes, but the good news is they are easy to build oneself and almost always work fine. I can think of no instance where a properly made adapter, 5-3 or adapter, 3-5 did not work.
Just wire both ends pin to pin: pin1=pin1, 2=2, 3=3. Leave pins 4&5 unwired on the XLR5.

I guess you could make them if you were desperate. But it doesn't make much sense when you can buy them for less than $10.

 

[121 Gigawatts]

The A&B inputs let you merge, do houselights or failover. Imagine a 96 way dimmer pack with 72 dimmers as the lighting rig and 24 as the house lights, fed from two different controllers etc.
As for the 3-pin vs 5-pin. 5 pin is the actual standard and is found on most pro gear. 3 pin was done on low end budget gear so folks could use microphone cables (even though 3 pin data is different from 3 pin microphone cable.)

OK now makes sense, thanks.