The relay is a SPDT switch...it has both a normally on and a normally off output. Optimally, you want the relay coil energized only when you want the door to be open so you would wire the relay so that the 12VDC is connected to the center and the side that shows as open : ----/ ---- is connected to the other wire to the door. That way, the coil is energized and using power only when it is activated.
If you issue a
command, the door should unlock until a GPIO write 26 0 is issued. Apologies if this is repetitive.
Sent by WH7QQ from an RPi3/Raspbian/pixel desktop.