Garmin GPS 15 Technical Specifications

Also see for GPS 15: Technical specifications

Garmin GPS 15 Technical Specifications Manual pdf 16 page image

GPS 15 Technical Specifications (P/N 190-00266-00) Rev. BPage 104 GPS 15 SOFTWARE INTERFACEThe GPS 15 interface protocol design on COM 1 is based on the National Marine Electronics Association’sNMEA 0183 ASCII interface specification. This standard is fully defined in NMEA 0183, Version 2.20.Copies may be obtained from NMEA, www.nmea.org.The GPS 15 interface protocol, in addition to transmitting navigation information as defined by NMEA0183, transmits additional information using the convention of Garmin proprietary sentences. Theseproprietary sentences begin with the characters, “$PGRM”, instead of the characters “$G” that are typicalof the standard NMEA 0183 sentences. The characters “$P” indicate that the sentence is a proprietaryimplementation and the characters and “GRM” indicate that it is Garmin’s proprietary sentence. The letter(or letters) that follow the characters “$PGRM” uniquely identifies that particular Garmin proprietarysentence.The following sections describe the NMEA 0183 data format of each sentence transmitted and received bythe GPS 15.4.1 RECEIVED NMEA 0183 SENTENCESThe following paragraphs define the sentences that can be received on the GPS sensors’ port. Null fields inthe configuration sentence indicate no change in the particular configuration parameter. All sentencesreceived by the GPS sensor must be terminated with , the ASCII characters for carriage return(0D hexadecimal) and line feed (0A hexadecimal), respectively. The checksum *hh is used for paritychecking data and is not required, but is recommended for use in environments containing highelectromagnetic noise. It is generally not required in normal PC environments. When used, the parity bytes(hh) are the ASCII representation of the upper and lower nibbles of the exclusive-or (XOR) sum of all thecharacters between the “$” and “*” characters, non-inclusive. The hex representation must be a capitalletter, such as 3D instead of 3d. Sentences may be truncated by after any data field and validfields up to that point will be acted on by the sensor.4.1.1 Sensor Initialization Information (PGRMI)The $PGRMI sentence provides information used to initialize the GPS sensor’s set position and time usedfor satellite acquisition. Receipt of this sentence by the GPS sensor causes the software to restart thesatellite acquisition process. If there are no errors in the sentence, it will be echoed upon receipt. If an erroris detected, the echoed PGRMI sentence will contain the current default values. Current PGRMI defaults(with the exception of the Receiver Command, which is a command rather than a mode) can also beobtained by sending $PGRMIE to the GPS sensor.$PGRMI,<1>,<2>,<3>,<4>,<5>,<6>,<7>*hh<1> Latitude, ddmm.mmm format (leading zeros must be transmitted)<2> Latitude hemisphere, N or S<3> Longitude, dddmm.mmm format (leading zeros must be transmitted)<4> Longitude hemisphere, E or W<5> Current UTC date, ddmmyy format<6> Current UTC time, hhmmss format<7> Receiver Command, A = Auto Locate, R = Unit Reset