REFERENCE MANUAL - FTP Directory Listing - Trimble

NMEA 0183
C
Note – Spaces are only used in variable text fields.
Units of measure fields are appropriate characters from the Symbol column (see
Table C.2), unless a specified unit of measure is indicated.
Fixed length field definitions show the actual number of characters. For example, a
field defined to have a fixed length of 5 HEX characters is represented as hhhhh
between delimiters in a sentence definition.
Invalid Command Set
In the case that a command is sent with incorrect data, the NMEA sentence
$PTNLRxx,V*xx is a generic response.
Checksum
The checksum is the last field in an NMEA sentence and follows the checksum
delimiter character “*”. The checksum is the 8 bit exclusive OR (no start or stop bits)
of a character in the sentence including “,” between but not including the “$” and the
“*” delimiters. The hexadecimal value of the most significant and less significant 4
bits of the result is converted to two ASCII characters (0-9, A0F (upper case)) for
transmission. The most significant character is transmitted first. Examples of the use
of the checksum field are:
$GPGLL,5057.970,N,00146,110,E,142451,A*27
$GPVTG,089,0,T,,,15,2,N,,*7F
Copernicus GPS Receiver 215