I am trying to improve the design of an alarm/access system we manage to eliminate false alarms. Basically we need to have the alarm system armed whilst people come and go without them having to arm and disarm the system. What we have is an electronic access control system that operates the door and a sensor that operates a timer relay to shunt the door magnetic contacts for a given time to maintain the armed state w/o an alarm for the time that the door cycles (plus a few seconds).
The problem is that this timer relay does not reset upon closure of the door, it resets only when the set time expires, so someone following along, but perhaps just around the corner and thus out of sight, can't know the status of the timer and may hit the door before it resets, thus causing an alarm.
What we need is a timer relay that will activate as our current one does but will reset instantly upon the next instance of closure of the door alarm magnetic contacts. So if the door is closed, the users will know that it is OK to exit.
Anyone here know if such a relay or control module exists?