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PinPoint EDGE/GPRS - User Guide, version 2.32 44
Global Positioning System (GPS)
Store and Forward for RAP
Store and Forward RAP can provide seamless coverage even in areas with intermittent cellular
coverage. If the PinPoint leaves coverage or has very low signal (an RSSI of -105 or lower), it will
store the GPS messages in memory. When the modem re-enters cellular coverage, it will then for
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ward the messages as configured. The PinPoint can also store messages and send them to the
server in a packet rather than individually to conserve bandwidth.
FIGURE 17. Wireless Ace: Store and Forward
Once you have enabled SnF, *PPSNF, you can determine how you want the messages sent using
*PPSNFB, Store and Forward Mode:
Normal - Each report is sent immediately.
Polled - Reports held until requested by the server.
Grouped - Reports held until the total is equal or greater than *PPSNFM which sets the packet
size of grouped reports.
Store and Forward Reliable Mode
The Store and Forward Reliable Mode allows the PinPoint to ensure all messages are received by
the server even if the connection between them goes down for a period of time (such when a vehi
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cle passes through a location where the cellular signal is weak or non-existent).
FIGURE 18. Wireless Ace: Store and Forward Reliable Mode
With Reliable Mode enabled, *PPSNFR, the PinPoint will transmit a sequence number (1 to 127)
as part of a packet of messages (may contain one or more reports). To reduce overhead, the server
only acknowledges receipt of every eighth packet. The PinPoint considers that 8 a “window” of
outstanding packets.
If the PinPoint doesn’t receive acknowledgement for a “window”, the modem will PING the server
with a message containing the sequence numbers of the first and last packets that haven’t been
The report type will indicate the state of change in the inputs. The contents of the report will be
the same as Report Type 0x12 (GPS data with date) or 0x13 (GPS data with date and RF data)
with the addition of the event report.