how to connect siren to dvr output

[chen27 0]

Hi everyone, in the back of the dvr I saw that there are outputs (3) In what would be the (2) relay_common. But if I turn the siren on, it will not work. How should she call? And if it is to connect a lamp 127v together would have to have a 12v relay as would make that connection?

[tube tech 1]

1) try 2 & 15, Relay 1 common and Relay 1 NO

2) don't run AC through your DVR. use those connections to run an external relay