Just want to let you guys know that it works like a charm! No more false alarms and it does not trigger the alarm when the IR cut is activated!
This is how I made it:
The DCS-2230 (never mind the wires)
An electrical IP65 box witch I prepared for the Fresnel lens.
The Pyroelectric Infra-red PIR Motion Sensor Detector Module HC-SR501
The result, mounted outside on the wall, well protected from dust and rain.