So upfront - I’m trying to work out exactly what hardware I need and I’m a bit lost.
I think I need a dry contact relay like the Sonoff Mini-D but recommendations welcome.
I have a controller for a roller door which has terminals for connecting external buttons or keyswitch, these are terminals 8,9 and 10 in the diagram below.
I believe they are low voltage, essentially a switch connecting terminal 8 to 9/10 depending on direction.
I’d like to keep this controller in place 1) for the wife approval factor so she can keep her fob and 2) it already has limits in it for stopping the door going too far up or down meaning one less thing I have to sort.
I think something like the Sonoff Mini-D would work, connecting the common terminal 8 to com on the mini-d and then 9 to NC and 10 to NO.
It seems your guess is good. Do you need to wire it in parallel with the key switch or in it’s place?
If the former you should be careful of not issuing contradictory commands (key up, smart switch down)
You should test with a simple switch if you need to keep the button pressed till is fully open or fully closed.
The sonoff you suggest is not good (alone) you should use 2 relays. The common wire should go to both then from these use the NO output to the controller.
The up/down commands how are implemented by the controller?
I see these cases:
You just need to short common and up/down for a few dozens of ms to enable the full motion
You need to keep the connection closed until the motor reach the desired position then
a. you need to open the circuit once the thing is fully opened/closed
b. you can keep the switch in that position until you need to reverse the motion
And more: in this last case (2.b) what happens if, on a stedy fully opened/closed state (and the circuit stil set to that configuration) the controller get another input from the other remote/fob?
I have not experience with the Sonoff you proposed but, based on the contact description on the iring schema from sonoff, there is a common “input”, a Normally Opened output and a Normally Closed one.
EDIT: I’m intepreting this beahavour from the sonoff as: when you set the relay to ON the Common-NO circuit is closed an the Commono-NC is opened, the reverse is true when you set the relay to off
In the case nr1 you need 2 switches relays, a common wire goes to both and the NO contact of the first go to UP the output of the other goes to DOWN, then you need to implement the logic of shortening only one of the two relays and for as little as it takes to start the action
In the 2.a case you need the same setup but with a longer action time (to be discovered and implemented via automation)
The only case where you can use a single relay is the 2.b case where you use eg NO for UP and NC for down and toggle the relay with each command.
That’s why I was suggesting to use a simple button or even a short piece of electrical wire to test the controller, wire it to the common and then short it to UP or Down and see what happens if you remove the connection once the motor kick in.
