Campbell Scientific GPS16X-HVS GPS Receiver - Manual (Page 27)

Appendix B. CR23X Wiring and Programming
B.2.2.1 CR23X Example of Instruction 15 (P15)
Port Serial I/O (P15)
1: 1 Reps
2: 66 -- RS-232 ASCII (decimal delimiter), 38400 Baud
3: 1 Delay (units = 0.01 sec)
4: 5 Control Ports
5: 1 Output Loc [ Bulk ]
6: 0 No. of Locs to Send
7: 42 Termination Character
8: 100 Maximum Characters
9: 80 Time Out Delay (units = 0.01 sec)
10: 1 Loc [ Raw_time1 ]
11: 1 Mult
12: 0 Offset
Communication cable wiring for:
CR23X/Example B.2.2.1 — PPS to C8, GPS transmit to C5.
B.2.3 Filters
Filters can be used to make sure P15 reads the correct data string. Filters also
ensure P15 starts to read the string at the beginning of the string. To use a
filter, follow P15 with instruction P63 (extended parameters). P63 is used to
define the filter. Enter the desired filter in P63.
TABLE B-3. Filter
ASCII Equivalent Character
36
$
71 G
80 P
71 G
71 G
65 A
B.2.4 Managing the Data
Several of the data values in the $GPGGA string are too large to view or write
to final storage. Some simple math is used to parse the data.
The UTC time is in the format hhmmss where hh is the hours, mm is the
minutes and ss is the seconds. Six digits are too many to view with the
datalogger display and some software. Add 0.3 to the raw time field. Multiply
the raw time input location by 0.01 to reduce the magnitude and place the
seconds in the fractional portion of the number. Next use P45 to write the
integer portion (hours/minutes) to a new input location, then use P44 to write
the fractional portion to another input location (seconds) and multiply that
NOTE
B-3