I have new news that I would like for someone to confirm. I have heard from an installer that the 12v trigger output on the projector is actually a 12v continuous out while the system in on and 12v off when the system is off.
For a continuous 12v Signal:
The circuit I have designed is very simple. I have employed a DPDT relay that toggles between poles when activated. The continuous 12v holds its postions. It will be at one pole when no trigger is supplied and on the other when activated with the 12v trigger current. I have used this DPDT to reverse the current to the motor when in the 2 different positions of the relay, Thus, it has a separate up (direction) current path and a down (direction) current path. I have then added a normally closed limit switch to each of the 2 paths Up and Down that will break the current to the motor when the switch is tripped by the lift arriving to its up or down position.
So when the 12v trigger is supplied the lift moves down until the limit is reached and the current is stopped by the limit switch. Then when the 12v trigger current is removed, the relay returns to the other (reversed) position and moves the lift up until the upper limit is reached and current is broken by the second limit switch.
Next time the projector provided the 12v current we start all over again.
For a momentary 12v trigger:
I have found a relay that is DPDT that will toggle on a momentary 12v pulse. It must however also have a continuous 12v supplied by a separate source to hold the relay in its latched position until the next pulse.
Thus, either way, I think I am covered.
Scott, thanks for the help and the link to Altronics. They have the toggling relay and set me on the right direction.
