Garmin 16-HVS Instruction Manual

Also see for 16-HVS: Instruction manual Instruction manual

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Garmin 16-HVS Instruction Manual Manual pdf 14 page image

Appendix A. CR23X/CR10X ProgramsA.1 ProgrammingProgram instruction 15 (P15) is used to read the NEMA $GPGGA string oftime and position data. Each iteration of P15 can either read the numeric fieldsor read everything. When reading the numeric fields, such as time, latitude,longitude and elevation, P15 requires non-numeric delimiters between datapoints. The only available format of GPS data with delimiters is the NMEA0183 format. Program instruction 15 (P15) reads serial data and discards non-numeric values. All non-numeric values act as delimiters between numbers,and decimal points can also act as delimiters. P15 can be used to importeverything in the string, character by character, and convert it to the decimalequivalent. The decimal equivalent method is seldom used, and only when thegeneral area (hemisphere) is not known.A.1.1 Program Execution IntervalDue to the sequential program instruction execution of the CR10X and CR23Xthe Port Interrupt Subroutine 98 is useful in synchronizing the GPS16-HVSmeasurement via the Pulse Per Second output. When the PPS signal is used totrigger the read data function (P15), the program table execution interval doesnot matter. Otherwise the timing between the GPS16-HVS output and thedatalogger read must be considered. Generally the execution interval can notbe less than 2 seconds when the PPS signal is not used. This is discussedfurther in Section A.1.5.A.1.2 Reading GPS DataTable A-1 is a sample CR23X P15 instruction for reading NMEA $GPGGAdata string. The second parameter has two dashes indicating data buffering hasbeen turned off. The CR10X does not have the data buffering option.TABLE A-1. P15 for NEMA $GPGGA Data StringParameter Data Description1 1 Repetitions2 61 -- Configuration code for RS232 ASCII data at 1200 baudwith data buffering turned off. The -- indicates databuffering turned off. Decimal delimiter3 1 Delay before sending data out4 05 Control ports. Two digit format AB. A is forhandshaking and set to zero. B in this example is controlport 5 (datalogger RCV). GPS16-HVS communicationcable: GPS transmit to control port 5 in this example5 1 Input location where first character to transmit is stored.Note: nothing is actually transmitted6 0 Number of consecutive input locations to send7 42 Termination character, 42 is ASCII equivalent of theasterisk8 100 Maximum number of characters to receive.9 80 Delay in mS. How long to wait for $GPGGA string10 1 Starting input location for time and position dataA-1