Digital Watchdog VMAXD1 16 User Manual page 19

Relay
Select from NO (Normally Open) or NC (Normally Closed).
If the wrong type is selected, relay will not work.
NO, which is normally open, closes when a signal is received.
NC, which is normally closed, opens when a signal is received.
Relay Output Connection
Relay output signal to external device such as Alarm or Siren.
Connect relay to R1, R2, R3, and/or R4 of the terminal block, located on the rear side with R#_Com Port.
Number of relay varies depending on the model of the DVR.
19