@dc42 I forgot to mention in that post that I was wrong about the TTL being active low. S255 is full power and S0 is off.
@resam I'm going to get a separate switch for the laser's power so it won't be powered until I'm ready to start a 'print'. That way when I power the laser on, the config will already be loaded and there shouldn't be a full power spike.
I should have one for other safety reasons anyway.