External Siren to Dahua KTP02 - VTH2421FW

[CAMGUYx86]

I have 2 wires siren I would like to add to VTH2421FW.

I did the following wiring:
COM DC +12V
NO Siren
DC -12V Siren

However, if door is open for certain time, internal beep on VTH is triggered and siren is not working.

Any advice if this setup is correct? Is it possible to allow external siren to work side by side of internal VTH alarm sound?

 

[TonyR]

Did you follow these steps found here to configure and enable the alarm?

 

[CAMGUYx86]

I don’t have this option! Possibly missing after new interface upgrade?