DR + GPS
STARTER KIT REFERENCE MANUAL
Lassen DR + GPS Reference Manual 48
Command Message Structure (Host to Module)
Command messages sent from host to module are built upon the report message
structure. Except for system commands such as system reset, every command
either sets or queries a reportable data structure. To accomplish this, the HIPPO
set or query command protocol simply “wraps around” the report message
protocol (see tables below).

Table 12: HIPPO Command Message Structure

Byte Meaning Value
SOM start of message 0x81
CCOD Set Command code 0x01
PCOD Parser code 0x00 – 7F
PSUB Parser subcode 0x00 – 7F, 0xFF
D[0] First byte of data 0x00 – FF
D[1] Second byte of data 0x00 – FF
… …
D[N-1] Last byte of data 0x00 – FF
CS Checksum 0x00 – FF
EOM End of message 0x82

Table 13: HIPPO Query Message Structure for Indexed Data

Byte Meaning Value
SOM Start of message 0x81
CCOD Query Command code 0x02
PCOD Parser code 0x00 – 7F
PSUB Parser subcode 0x00 – 7F
INDEX Index 0x00 – 7F, 0xFF
CS Checksum 0x00 – FF
EOM End of message 0x82
Chained Messages
Chaining is not supported in the DR GPS module. If multiple messages are
requested, they will be issued as time allows between the high-priority automatic
report messages. An acknowledgment message appears at the end of the
sequence of replies.