Garage door wall control communication

[joegtp]

I've been trying to figure put how my garage door wall control communicates with the motor. It's definitely bidirectional because it can display sensor status. What I find puzzling is that there are only two wires going from the wall control and the motor box. I guess it could be RF but that seems strange since it has a lock out button as well.

[David_AVD]

Low voltage DC with the data modulating the power would be my guess.

[amyk]

Should be rather easier to figure out if you can take it apart...

[SeanB]

Simplest is to use a set of resistors switched to show the various functions in the box, and provide a constant current down the wire that drives a LED for status, with the current being lowered to indicate a fault. Other method is to modulate the data over the wires and have a micro inside the remote side that reads the supply voltage to get data and pulses the line to a low level to send data back.