Wiring Contacts for External Doors that also have heavy Security Screen Doors


New Member
Security Screen Doors are the norm in Australia especially in the tropics where the mosquitos can try & carry us away, while other times they are needed to stop flies.
Our security screens are stainless steel mesh "Crim Safe" that are fitted to the outside of our doors.  
The mesh is heavy & can't be easily cut.  
It is held in by fairly thick aluminium strips that are screwed very regularly.  
Three point locking locks are fitted.
You can't cut or kick your way through the Crim Safe although I guess a modern battery operated angle grinder would work.
If the Security Screen Door is locked then it doesn't matter if the Exterior Door just inside it is open.  
If the Exterior Door is closed then it doesn't matter if the Security Screen Door just outside it is open or closed.
If one or the other is secured then the system is secure.
I can use a pair of reed contacts (one on each door) wired so that if Exterior Door is closed then the Security Screen Door contacts are bypassed so that it isn't detected or I suppose it can be done with programming.
What is the best way to do this?
I will be using a M1Gold.
I haven't started playing with the programming yet.
I think the most simple way to do this would be to wire the two contacts in parallel to a single zone input, such that if either contact is closed, then the zone will be secure.
I can see where it would be nice to know the status of each door, and be able to tell if one of them has been left open.  But if you wire each one to it's own zone, then it becomes more difficult to trigger an alarm.  You would only want to trigger an alarm if both are violated, and would like to use rules to do this. But the M1 doesn't allow you to trigger an alarm directly using rules.  About the best you can do would be to use a rule to activate an output to drive a relay which in turn would trigger an alarm via a separate zone input.
I was intending to use EOL resistors.  
I was also thinking of a series / parrallel contacts so the outside security door contact is disconnected from circuit when the inside door is closed.
I'm a retired sparky & tech so I guess I tend to use over kill.
I want to make it as fool proof & reliable as I can.