User's Manual

DRAFT TrimTrac 1.5 Technical Manual v0.3ab 20
transmitted alert messages will have Report Sequence Numbers lower than the
alert message first received by the server application.
Finally, the TrimTrac 1.5 message log could be completely filled with alert
messages if the device remained outside GSM coverage for a long enough time
period while one or more alerts were activated. The message log will hold up to
1,024 most recent messages. Once full, new messages will overwrite the oldest
messages.
Motion Report Flag
If a TrimTrac 1.5 has been a rest for a while, it is likely in the IDLE State. Once
the device starts to move, it will normally wake up, start computing a new GPS
position and then report it. Depending upon the GPS signal at the time and how
long it has been since the device computed its last position, the time to compute
and report a new GPS fix can vary. Moreover, if there is insufficient GPS signal
to compute a new fix, no new message will be sent to the server application until
the FIX State Timeout, T2, has expired.
If the application requires more immediate notice that a device, which should be
at-rest, has started to move, then the Motion Report Flag should be enabled. In so
doing, the device will send an immediate STATUS_MESSAGE to the server
application that motion has commenced. After this initial STATUS_MESSAGE
is sent, then the device will go compute a new position fix and commence further
reporting in accordance with its other configuration settings.
Report Delay Flag
This is an extremely important parameter used to help manage communication
costs. It has little, if any, impact on power consumption, but it is instrumental in
minimizing communication costs. Basically, the Report Delay Flag selectively
suppresses the transmission of messages until certain events occur or messages
are received from the server application.
For instance, setting the Report Delay Flag to “1” suppresses all normal position
reports and status messages (except queries, scheduled reports, and priority and
geofence alerts) even though the device is cycling through the state machine in
background. Based on motion, it will be computing and logging, but not
transmitting, new position fixes. These logged positions can be subsequently
retrieved by the server application by sending the TrimTrac 1.5 the appropriate
query message. The server application can change the device configuration or
query it for other information and still get a response even if the Report Delay
Flag is set to suppress some or all other messages. All alert, query and, if
enabled, Scheduled Reporting Mode messages are transmitted regardless of how
the Report Delay Flag is set.