Alarm Triggers

Alarm Triggers

Door Contact Signals

The status of the door contacts is evaluated by the CAS and transmitted by K-CAN-S telegram. The status of the individual door contacts is included in the alarm table 3 s after the status signal "door closed" is generated.

It is possible to trigger an alarm via a closed door even if another door contact is still open.

In the case of faulty or implausible lid signals, the CAS assumes that the contact is closed.

Trunk Lid

The status of the trunk lid contact is evaluated by the CAS (from the PM) and transmitted to the DWA by telegram.

If the trunk lid is unlocked when the DWA is armed, then signals from the trunk lid contact, interior sensor and tilt sensor are deleted from the alarm table.

Three seconds after the trunk lid is locked, the trunk contact is re-included in the alarm table and the referencing period of the interior sensor and tilt sensor commences (provided no other door or lids are opened).

Hood

The status of the hood contact is evaluated by the CAS and transmitted by telegram. The status of the hood contact is included in the alarm table 3s after the status signal "hood closed" is generated.

Interior Sensor

The interior sensor monitors movements in the passenger compartment of the vehicle. The referencing phase of the interior sensor begins 3 seconds after locking the last doors and lids.

The interior sensor is ready 20 seconds after the referencing period begins. The trigger is included in the alarm table.

Tilt Sensor

The referencing phase of the tilt sensor is started by a telegram from the DWA 3 seconds after locking the last doors and lids. The tilt sensor is ready 30 seconds after commencement of the referencing period and indicates this to the DWA. The trigger is now included in the alarm table.

If no acknowledgement telegram is sent from the siren/tilt sensor, this is registered in the memory of the DWA and the tilt sensor is not included in the alarm table.

If the ready tilt sensor detects an alarm trigger situation, it informs the DWA using a DWA K-bus telegram. The DWA decides whether to generate the alarm or not based on the predefined criteria.

The tilt sensor alarm is stored in the DWA interior sensor. To prevent a false alarm from triggering caused by a rocking motion of the vehicle, the angular data for the longitudinal arm and control arm are detected every 90 ms. An alarm is only triggered if the vehicle remains at a certain inclination for a sustained period of time (approx.1.5s).

Battery Switch

If the DWA receives the "Storage mode" telegram from the Power Module (change of signal edge from inactive to active) in the armed state, an alarm is triggered.

If the DWA receives the "Storage mode" telegram in the disarmed state, the DWA can be armed as usual. The tilt sensor and interior sensor remain active.

Self-Monitoring of Siren

The self-monitoring function is implemented in the siren. The siren triggers an independent alarm under the following conditions:

- An independent alarm may be triggered only once for each arming cycle.
- The self-monitoring of the emergency siren is started as soon as the DWA is armed. The emergency siren monitors its own power supply and identifies under-voltage, over voltage and open circuits.
- If the emergency siren recognizes an attempted manipulation, it indicates this to the DWA by telegram regardless of whether the DWA K bus is affected.

Monitoring of the DWA K Bus

The DWA communicates with the emergency siren and the tilt sensor over the DWA K bus. Monitoring is started as soon as the DWA is armed.

The DWA sends the telegram to the Monitoring device cyclically (every 2s) and expects a reply telegram from the emergency siren within a max. permissible reply time of 100 ms.

If the reply telegram is not received within this period of time, the telegram is sent to the monitoring device another two times. If the reply telegram is still not received after this, the DWA triggers an alarm using the Light Module and the vehicle horn.

DWA K-bus monitoring is deactivated when the DWA measures a vehicle voltage of 8.5 V.