One of the motion detectors activates the external sirene without activating the control panel, how Can I make sure this doesn't happen.

Alarm systems, Sensors and accessories / Alarms, Detectors, Sirens / ES-S6A, ES-S7A, ES-S7B, ES-S8A

the detector is probably connected to the out side sirene as a "stand - alone" alarm,Preform a reset and connect the sirene before the detectors making sure none of them are in the detection field of the sirene and vice versa