On April 23, 2008 at 15:39, TOOOLDAND TOOGRUMPY said...
failing that you can always utilise two relay outputs
of the RP-6 to simulate having a cold contact wall switch
This is how I usually control those type of screens. It's the same number of conductors as the RS232, and much less complicated. If I remember right you can also do a stop command by pulsing both contacts at the same time as well.