Campbell GPS16X-HVS, Instruction Manual

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Appendix B. CR23X Wiring and Programming
B.2.2 Reading GPS Data
TABLE B-2 is a sample CR23X P15 instruction for reading NMEA $GPGGA
data string. The second parameter has two dashes indicating data buffering has
been turned off. The CR10X does not have the data buffering option.
TABLE B-2. P15 for NMEA $GPGGA Data String
Parameter Data Description
1 1 Repetitions
2 66 -- Configuration code for RS232 ASCII data at 38400 baud
with data buffering turned off. The -- indicates data
buffering turned off. Decimal delimiter
3 1 Delay before sending data out
4 05 Control ports. Two digit format AB. A is for
handshaking and set to zero. B in this example is control
port 5 (datalogger RCV). GPS16X-HVS communication
cable: GPS transmit to control port 5 in this example
5 1 Input location where first character to transmit is stored.
Note: nothing is actually transmitted
6 0 Number of consecutive input locations to send
7 42 Termination character, 42 is ASCII equivalent of the
asterisk
8 100 Maximum number of characters to receive.
9 80 Delay in mS. How long to wait for $GPGGA string
10 1 Starting input location for time and position data
11 1 Multiplier, always 1.
12 0 Offset, always 0.
P15 parameters 4, 5, and 10 are somewhat variable. When using a CR23X,
parameter 4 can be set to 05, 06 or 07 depending on what control ports are
used. Wiring of the communication cable depends on the selection for
parameter 4. With a CR23X the GPS transmit wire is connected to the control
port selected in parameter 4.
P15 is executed when the PPS signal drives control port 8 high. P15 will wait
until one of three conditions is met: the time-out listed in parameter 9 has
expired, the maximum number of characters in parameter 8 have been read, or
the termination character listed in parameter 7 has been read.
P15 parameter 10 is the first input location you wish to store GPS data in.
Fifteen sequential input locations will be used to store time and position.
B-2