DR + GPS
STARTER KIT REFERENCE MANUAL
Lassen DR + GPS Reference Manual 52
The Query class packet allows user to retrieve configuration, report, and system
data with the same packet. Like the Set class packet, it is indexed by the report
code and subcode. This is possible because each parameter or set of
parameters has a corresponding report message.
Four types of parameters can be queried.
1. System parameters (e.g., version numbers)
2. Configuration parameters (e.g. DOP mask)
3. Fix parameters (e.g., satellite strength, current position, velocity, time,
ephemeris)
4. Initialization parameters (e.g., position, velocity, time, ephemeris)
The target system returns an acknowledgment packet. When a query for a single
report is successful, the reply to that query is the acknowledgment. If the query
fails, an explicit acknowledgment report message is sent as an acknowledgment.
If the query generates a series of response messages, the last response is
followed by an explicit acknowledgment report message that signals the end to
the host’s parser.
A query has two formats, depending on whether the information is indexed (e.g.,
by channel or satellite).
Table 16: Query Class Message Structure
Byte Name Type Value Meaning
Command Code U8 0x02
Parser Code U8 0x00-7F
Parser Subcode U8 0x00-7F
0xFF
Single Subcode
All subcodes