Hi,
you might want to contact Gento; check out his little baby:
http://www.gento.de/Safety_Input.pdf
as featured here:
http://www.laserfreak.net/forum/view...er=asc&start=0
It basically says:
* up to 8 (color) channels can be switched
* additional mechanical releais for shutters
* determine scan area via x and y settings, everything else is no-go
* watchdog checks for CPU faults
* etc.
* probably < $200 (?, well, you gotta ask him about the price...;-))
Cheers
Christoph