I built an automatic chicken door to let my chickens out in the morning and lock them in at night. It works great. I have the actuator and 2 channel wifi switch that works through google home and allows me to put it on a timer. However I want to add a sensor that would stop the door from coming down if a chicken or dog was in the way.(already killed 2 chickens)it doesnt have to go back up, just stop from coming down. I bought a normally open npn photoelectric sensor (not sure even if this was the correct one to buy) and dont know how to wire into my system to make it work or even possible. Do I need to add an relay or is my 2 channel wifi relay enough? Although my system works I have very limited skills. I followed a video to get this going but want to add a sensor. Thanks for your help.