3DM
®
-GX5-35
DCP Manual
4.2.6
GNSS Message Format (0x0C, 0x09)
Description
Set, read, or save the format of the GNSS message packet. This function sets the format
for the GNSS MIP data packet when in standard mode. The resulting message will main-
tain the order of descriptors sent in the command. The command has a function selector
and a descriptor array as parameters.
Possible function selector values:
0x01 – Use new settings
0x02 – Read back current settings.
0x03 – Save current settings as startup settings
0x04 – Load saved startup settings
0x05 – Reset to factory default settings
The rate decimation field is calculated as follows for GNSS messages:
Rate Decimation = GNSS Base Rate / Desired Data Rate
You should always retrieve the Base Rate from the
command
for computing the desired rate decimation. Base rates vary from device to device. The
GNSS base rate for the 3DM-GX5 is 4.
The device checks that all descriptors are valid prior to executing this command. If any of
the descriptors are invalid for the GNSS data descriptor set, a NACK will be returned and
the message format will be unchanged. The descriptor array only needs to be provided if
the function selector is = 1 (Use new settings). For all other functions it may be empty
(Number of Descriptors = 0).
Field Format
Field Length
Field
Descriptor
Field Data
Command
4 + 3*N
0x09
U8 – Function Selector
U8 – Number of Descriptors (N)
N*(U8 – Descriptor, U16 - Rate Decimation)
Reply Field 1:
ACK/ NACK
0x04
0xF1
U8 - echo the command descriptor
U8 - error code (0: ACK, non-zero: NACK)
Reply Field 2:
Function = 2
3 + 3*N
0x81
U8 – Number of Descriptors (N)
N*(U8 – Descriptor, U16 - Rate Decimation)
Examples
MIP Packet Header
Command/Reply Fields
Checksum
Sync1
Sync2
Desc.
Set
Payload Length
Field
Length
Field
Desc.
Field Data
MSB
LSB
Command:
0x75
0x65
0x0C
0x0A
0x0A
0x09
Function: 0x01
0x16
0x85
40
