Tow Alert Parameters (TOWP)
A tow alert (i.e. report with REASON bit set indicating tow alert event) is generated whenever
movement is detected whilst the vehicle ignition is off. This scenario is detected using a number
of different sources, including GPS speed, GPS location and accelerometer based motion sensor.
The sensitivity of tow alert detection can be changed by editing the various decision thresholds
using the TOWP command. The format of the command is as follows
$TOWP,<distance_metres>,<speed_kmh>,<speed_seconds>,<motion_sensitivity>
Field
Description
Range
<distance_metres>
distance travelled from the
last ignition off position that
will trigger a tow alert
0
disables distance check
100 – 65535
<speed_kmh>
speed threshold to trigger a
tow alert. The speed must
exceed the threshold for the
time in the <speed_seconds>
field to trigger an alert.
0
disables speed check
20 – 65535
<speed_seconds>
time for which the speed
must be above the threshold
in the field <speed_kmh> to
trigger a tow alert.
1 – 65535
<motion_sensitivity> accelerometer based motion
detection sensitivity for
triggering a tow alert.
0
disables motion detection
1 – 10
(1=most sensitive,
10=least sensitive)
There is a 60 second delay after the ignition is turned off before motion detection will trigger a
tow alert.
Once a tow alert has been generated further alerts will be reported by any of the following
conditions:
<distance_metres> travelled since the last reported position
Speed is lower than <speed_kmh> and then exceeds it for <speed_seconds>
Motion is detected and it is at least 60 seconds since motion previously triggered a tow
alert or ignition was turned off
If the ignition is turned on within 30 seconds of motion being detected then a tow alert will not
be generated.
