didn't you have to worry about dmx glitches, resulting in knifing an actor in the back? I've always heard that pyros and other stuff shouldn't be trusted with dmx.
Maybe i read the article wrong though.
Anyway, sounded like the run went well, and that effect must have been awesome, congradulations!
Actually, we really were, but for some reason, the electronics never experieced any glitches at all. The only night that the knives did misfire was when the deck crew who set them did not set the catches correctly, and even then it was a mechanical, not electronic failure.
Good question regarding safety and I would have used a kill switch (pardon the pun) in which power to the device was controlled separately by someone who has a line of sight for the effect. This person then only allows the mechanism to be powered up just prior to the effect being used and can cut power if someone gets in the way.
This is the reason for not automating pyro and why several safety measures have to be taken.
some good points thus far relating to killswitches and safety mechanisms. DMX isn't the best protocol for mission critical FX comm because of it's lack of checksum, something like RS-232 is more common than one might imagine in applications like this. Proprietary control systems are also pretty common, but I'd probably opt for a system seperate from the lighting network for serious or potentially dangerous effects.