Honeywell MPS51C Frequently Asked Questions

What Do Normally Closed and Normally Open Mean?
"Normal" is the normal state of an opening, such as a door. Normally open/closed refers to the state of a contact connected to a door in its normal position.

Honeywell Glassbreak vs Window Sensors
Glass break detectors and windows sensors are both used to protect against a break-in through a window, but they work in very differnet ways.