Q-See QSD2216 - Manual (Page 10)

10
2. Open/Close output
A: N.O. Normal open, close when triggered. DVR must set as low voltage alarm.
B: N.C. Normal close, open when triggered. DVR must set as high voltage alarm.
Please refer to the picture below, channel 2 to channel 16 are the same as channel 1.
Alarm output:
There are three alarm output pin, the status of these pin are illustrated as below
Before Alarm After Alarm
There is an example for alarm output connection