Gps Serial Protocol; Table 21: Approved Sentence Structure; Table 22: Nmea Field Definitions - NorthStar 8700 Technical Reference Manual

$PSLIB,0,(CR)(LF)
$PSLIB,,,R(CR)(LF)
$PSLIB,284.5,0(CR)(LF)

10.2 GPS serial protocol

Field type
Special format fields
Status
05/01/97 REV H
This section describes the serial protocol used by the GPS sensor to com-
municate with the host device. The serial communication runs under the
following setup:
Speed: 300 to 38,400 baud (default is 4800)
•
Format: 8-bit data, 1 start bit, 1 stop bit, no parity (10 bits/character)
•
Data information passed on the serial line is divided in one or more
NMEA-approved or proprietary sentences having the following structure.

Table 21: Approved sentence structure

Data field Contents
$PMCAG,xxx,xxx,xx,xx,...*CK<CR><LF>
Record sync character
$
Special ID (P = proprietary)
P
Originator ID (MCA = Canadian Marconi Company)
MCA
Interface ID (G = GPS)
G
Data (first field = message identifier)
xxx,xxx,x
x,xx...
Checksum field delimiter
*
Checksum
CK
End of sentence
<CR><LF>

Table 22: NMEA field definitions

Symbol Description
Single character field:
A
A = Yes, data valid, warning flag clear
V = No, data invalid, warning flag set
Return to automatic mode. The best broad-
cast available will be demodulated.
Restart.
Demodulate data from a DGPS beacon
broadcast at 284.5 kHz, with the bit rate to
be automatically determined.
Section 10 - NMEA protocols
PAGE 45