I'm trying to install a security system to the door of a room and I cant get the logic quite right. I also have the MD-HMI keypad so the purpose is to have the person entering the room enter a password on the keypad and have a signal sent to a striker which opens the door. For the people exiting, they should just be able to push a button on the inside and the striker will again open the door. Also, to detect whether the door is open or closed, I have a magnetic strip along the top of the door. If the door is opened, there should be a 15 sec countdown and then a buzzer should go off until door is closed. I've come up with this logic, but I am stuck:
Keypad Magnet Striker
|----||-----------------|/|-------------------(OUT)
| Button | | Duration
|----||------ ---------(TIM)
|
|
|
| Duration Magnet Buzzer
|----||----------------|/|--------------------(OUT)
|
The problem with this is that I want the Buzzer to go off only if the Magnetic strip is open(when the door is still open). With the configuration I have, the buzzer is going off if the magnetic strip is closed. How do I make the change? Or is there any way I can specify a condition to block an electrical signal to the buzzer? Any help would be much appreciated!