The limit switch is for the motor to know when to stop the gate, you can’t connect anything to it. Every motor will have a switch connection, similar to the garage motor. You can house the Sonoff SV in the motor case and connect it to the switch connections, only issue with that is you need to find a way to draw DC power to the Sonoff SV. My motor is 240VAC.
Hi,
I have recently done this with the same gate motor PCB.
We used a Shelly one to do the job, we powered the device with 230VAC off the gate board (terminals 1+2) and then used the relay of the Shelly one signal the gate open (terminals C+D) to open the gate.
We also tried to connect the limit switched into the input of the shelly to know when the gate is open but this didn’t work due to the circuit on the PCB so we used a magnetic reed switch mounted on the gate motor and rail to tell us when it is open.
Is is important to make sure the signal you send to the gate is a short pulse which can be set in the shellys web interface.
PS i don’t know much about the Z-wave devise and we only deal with shelly but maybe you can find a device that works the same.
We also set a nice tile up in HA and have a automation set up to close the gate after a set time and close the gate if no car is in the way.
Hope this helps.