Do I Need DMX?

[JonnyMac]

The question has been asked: Do I need DMX-512 for running props with VSA?

The answer, of course, is dependent on the number of channels you're running.  Let's say that you want to use our Prop-SX with VSA and all 16 channels populated.  Is 38.4K fast enough?

Yes, and here's proof: At 38.4K it takes 0.26 milliseconds to send a byte.  Each channel update using the MiniSSC protocol takes three bytes, so we're up to 0.78 milliseconds per channel update.  If we multiply that by 16 (channels) we can update everything in 12.5 milliseconds.  Two points to remember:

1) VSA only sends channel changes; so you'll rarely have 16 updates in one throw
2) The fastest frame rate in VSA is 33 milliseconds -- nearly 3x the time required to send all 16 channels.

As you can clearly see, 38.4K is plenty fast when using the Prop-SX.  Then why use DMX?  Well, if you have a huge number of channels (the -512 in the name indicates the number of channels) it works really well, especially if those channels are spread out all over the place.  DMX is super fast 250K; it transmits one byte in 40 microseconds (0.000040 seconds) -- this is what allows it to update all 512 channels in the frame time. 

What if you bought one of those cool Skulltronix skulls that runs from DMX and you'd like to add more to your display.  Can you integrate EFX-TEK products?  You bet.  In a few weeks we'll release our RS-485/DMX board that pops onto a Prop-SX to turn it into a DMX-compatible slave.  We're in the final testing of programs; the program options we have at this point: digital outputs, PWM outputs, and servo ouputs. 

To be fair, adding the DMX board to your Prop-SX cuts the usable channel count down to eight.  The reason for this is that the DMX module has a hardware address switch (this is a standard DMX practice) so that you can set the starting channel without reprogramming or doing an electronic configuration.

So... Got VSA?  Got DMX?  We've got you covered!