Campbell Scientific CR23X Micrologger User Manual
Page 253
APPENDIX B. CONTROL PORT SERIAL I/O INSTRUCTION 15
B-9
VTG Direction and Speed - 37 characters
including CRLF
$GPVTG,010,T,356,M,5.39,N,10.0,K*4FCRLF
Field
Data
Description
1. $GPVTG
message
identification
2.
010
Track made good in
degrees True
3.
T
True
4.
356
Track made good in
degrees Magnetic
5.
M
Magnetic
6.
5.39
Speed over ground in
Knots
7.
N
Knots
8.
10.0
Speed over ground in
Kilometers per Hour
9.
K
Kilometers per Hour
10.
*4F
Checksum
11.
CRLF
Carriage Return Line
Feed
The following program example will read-in the
GGA and VTG GPS strings. Since this program
is unique to the GPS application, additional data
processing will be required to decode and
format these strings. See Program Example #3
for a complete listing.
*Table 1 Program
01:
1
Execution Interval (seconds)
; READ IN SERIAL GPS DATA VIA NULL MODEM AND
; CR23X 9-PIN RS-232 PORT
1: Port Serial I/O (P15)
1:
1
Reps
2:
03
Configuration Code
;RS-232 ASCII, 4800 BAUD
3:
1
Delay (0.01 seconds)
4:
9
RS-232 Port
;GET GPS DATA VIA CSI 9-PIN RS-232
PORT
5:
0
Output Loc [ _________ ]
6:
0
No. of Locs to Send
7:
42
Termination Character
;ASTERISK *
8:
100
Maximum Characters
;GGA + VTG CHARACTERS
9:
100
CTS/Input Wait
10:
27
Loc [ RAW_TIME ] ;Input Location for first byte of received data
11:
1.0
Mult
12:
0.0
Offset
; CONFIGURE AND LOAD INPUT FILTER STRINGS
2: Extended Parameters (P63)
1:
36
Option ;$
2:
71
Option
;G
3:
80
Option
;P
4:
71
Option
;G
5:
71
Option ;G
6:
65
Option ;A
7:
0
Option
;END OF STRING 1
8:
36
Option ;$
3: Extended Parameters (P63)
1:
71
Option ;G
2:
80
Option ;P
3:
86
Option ;V
4:
84
Option ;T
5:
71
Option ;G
6:
00
Option
;END OF STRING 2
7:
00
Option
8:
00
Option