User's Manual

DRAFT TrimTrac 1.5 Technical Manual v0.3ab 11
Geofence Center
To establish a geofence area, whether circular or rectangular in shape, you must
first select the center point of the geofence area defined in latitude and longitude.
This can be done in three ways. Either you enter it into the TrimTrac 1.5 during
the provisioning process, by sending a TrimTrac Application command via the
GSM network, or, if the TrimTrac 1.5 is using either a Vehicle Adapter or Control
Module, by configuring the LPA input to define and/or enable a geofence based
upon the operation of a LPA switch.
It is acceptable to have geofences that overlap one another; however, having one
geofence located entirely inside the other should be avoided.
Geofence Shape and Size
Once the centerpoint of the geofence has been determined, you must then define
the overall dimensions of the geofence area. In the case of rectangular geofences,
you will need to define the due East-West and North-South lengths. Alternately,
you would define the diameter of the circular geofence area.
Since the geofences used by TrimTrac are orthographic projections, latitude and
longitude distortions increase further away from the center point. As such, the
maximum length of any given geofence dimension is limited to 1000 kilometers.
For rectangular geofences, this means no side can be more than 1000 kilometers.
The diameter of a circular geofence is similarly limited to 1000 kilometers.
Geofence Type
Finally, you will need to define the type of geofences that will be used. All
geofences in the TrimTrac 1.5 must be of the same type, of which there are three
choices: Boundary Crossing, Inclusive and Exclusive. In the case of Boundary
Crossing, the TrimTrac 1.5 will send a geofence-triggered report each time the
TrimTrac 1.5 detects it has crossed the boundary of an active geofence. This
report will be transmitted, along with a message indicating which geofence had its
boundary crossed, regardless of how the Report Delay Flag is set.
In the case of an inclusive geofence area used in conjunction with the Report
Delay Flag, the device will not normally transmit position or status messages
whenever it is located inside the defined geofence area. As soon as a position is
computed that is outside the geofence area, the device will commence
transmitting position and status reports as if the Report Delay Flag is set
“0=Transmit All Messages”. The device will continue transmitting in this mode
until the device re-enters the inclusive geofence area.
Conversely, the device will begin transmitting position and status reports
whenever the device is inside an exclusive geofence area.
The relevant parameters, settings, messages and commands used to defined and
activate geofences are set forth in Table 2 on the following page and in Table 89
on page 155.