190-00769-00
GPS 10x Technical Specifications
Rev. A
Page 13
APPENDIX A: BINARY PHASE OUTPUT FORMAT
In binary phase output mode, GPS 10x series products will transmit two types of packets once per second.
One record contains primarily post-process information such as position and velocity information. The
second record contains receiver measurement information.
Refer to the
Garmin Device Interface Specification
for details on how to form and parse Garmin packets.
At the time of this printing, these specs are available from the technical suppport section of our Web site at
http://www.garmin.com/support/commProtocol.html
For the GPS 10, the two records must be enabled independently by commands to the unit. The ID of each
command should be 10 decimal to signify that the record is a command. The data portion of the packet
should be one of the following:
Function Command
(base
10)
Position Record On
49
Position Record Off
50
Receiver Measurement Record On
110
Receiver Measurement Record Off
111
Note that the satellite data information is also enabled when the position record is enabled.
Records sent over RS232 begin with a delimiter byte (10 hex). The second byte identifies the record type
(33 hex for a position record and 72 hex for a satellite data record). The third byte indicates the size of the
data. The fourth byte is the first byte of data. The data is then followed by a checksum byte, a delimiter
byte (10 hex), and an end-of-transmission character (03 hex). Additionally, any DLEs (0x10) that appear
between the delimeters are escaped with a second DLE. There is sample code at the end of this section that
will strip off the DLEs and ETXs.
RS232 Packet:
- 0x10
(DLE is first byte)
- 0x##
(Record ID – single byte)
- 0x##
(Number of data bytes – single byte)
- data bytes
(See descriptions below)
- 0x##
(2’s complement of the arithmetic sum of the bytes between the delimiters)
-
0x10
(DLE)
-
0x03
(ETX
is
last
byte)
USB packets contain only the record ID, size, and data payload. Refer to the
Garmin Device Interface
Specification
for details on how to form and parse Garmin USB packets. The document is located on the
Garmin Web site at
http://www.garmin.com/support/ commProtocol.html.
USB Packet:
- 0x##
(Record ID – single byte)
- 0x##
(Number of data bytes – single byte)
- data bytes
(See descriptions below)
The data bytes of each packet contain the record specified by the record ID. A description of each record
follows.
