Retrieval; Command Message Acknowledgment - Ublox RCB-F9T Integration Manual

RCB-F9T - Integration manual
Figure 8: The states of the active logging subsystem

3.4.5 Retrieval

UBX-LOG-RETRIEVE starts the process which allows the receiver to output log entries. UBX-LOG-
INFO may be helpful to a host system in order to understand the current log status before retrieval
is started.
Once retrieval has started, one message will be output from the receiver for each log entry
requested. Sending any logging message to the receiver during retrieval will cause the retrieval to
stop before the message is processed.
To maximize the speed of transfer it is recommended that a high communications data rate is used
and GNSS processing is stopped during the transfer (see UBX-CFG-RST).
UBX-LOG-RETRIEVE can specify a start-entry index and entry-count. The maximum number of
entries that can be returned in response to a single UBX-LOG-RETRIEVE message is 256. If more
entries than this are required the message will need to be sent multiple times with different
startEntry indices. It might be useful to stop recording via CFG_LOGFILTER-RECORD_ENA while
retrieving log entries from a circular log to avoid deletion of the requested entries between the
request and transmission.
The receiver will send a UBX-LOG-RETRIEVEPOS message for each position fix log entry and a UBX-
LOG-RETRIEVESTRING message for each string log entry. If the odometer was enabled at the time a
position was logged, then a UBX-LOG-RETRIEVEPOSEXTRA will also be sent. Messages will be sent
in the order in which they were logged, so UBX-LOG-RETRIEVEPOS and UBX-LOG-RETRIEVESTRING
messages may be interspersed in the message stream.
The UBX-LOG-FINDTIME message can be used to search a log for the index of the first entry less
than or equal to the given time. This index can then be used with the UBX-LOG-RETRIEVE message
to provide timebased retrieval of log entries.

3.4.6 Command message acknowledgment

Some log operations may take a long time to execute because of the time taken to write to flash
memory. The time for some operations may be unpredictable since the number and timing of
flash operations may vary. In order to allow host software to synchronize to these delays logging
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