$$ X is used to input the binary code sequences for unlocking the lock. $$ Enter is used to tell the controller to read the current input value. $$ Reset$/$Lock is used to restart the entry process or to lock the lock after it$$s opened. $$ The lock will be opened $($Open $=1)$ if and only if code sequence X: $1-1-0-1-1$ is entered. $$ The controller must then stay in the Open $=1$ state until locked $($Open $=0).$