quote:Originally posted by Joe 1974 L #6656:
Hi Does200
Inquiring minds want to know when the door is down what state is the switch in?
Because right now you have one switch and then another switch which means one is open and one is closed. With the door up. The switch lets call it to the rear is not going to be used unless the first one fails.
My guess to the first question is the switch goes from open to closed when it hits the door.(it must pick up a relay in the unit) If it was the other way around the door would not stop until both switches were accuated.
The switches close when the slider hits them, and something in the motor control circuit tells the motor to reverse direction the next time someone activates the system.
In the above case, there is a triple redundant upper limit safety. If the first switch fails to close, then the second switch has a shot at turning the motor off. If that fails, or the motor control is faulty, the wood block is a physical barrier to prevent further travel. There is a clutch and a timed protection built into the opener that will stop the shaft from turning eventually turn off the motor.
These switches can operate momentarily and stop the motor, so if the slider hits the switch and coasts past the point of activation, the motor will stop, and be ready to reverse at the next button push.