This one is exactly what it sounds like: Held open time is the length of time a door can stay open before triggering an alarm. You installed an access control system for a reason, and so it’s fair to want to know who is using each space and forhow much time. When a cardholder unlocks a door with their badge, they could possibly hold the door open for someone who might not have the proper level of clearance to enter. To prevent this, you can define exactly how long a door can stay open before an alarm is triggered, alerting you to the problem.
This can be a different amount of time for each point in your system. For example, you’ll probably want a conference room to have a relatively long held open time to avoid an unnecessary alarm whenever someone holds the doors open for someone else in the meeting. For a lab or server room, however, the held open time should be just enough for one person because these areas require much higher levels of security.