SIM66 Series_NMEA Message_User Guide_V1.01
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2 NMEA Messages
2.1 General Format of NMEA Messages
NMEA messages use the ASCII character set and have a defined format. Each message begins with a
$ (hex 0x24) and end with a carriage return and line feed (hex 0x0D 0x0A, represented as <CR><LF>).
Each message consists of one or more fields of ASCII letters and numbers, separated by commas. After the
last field, and before the <CR><LF> is a checksum consisting of an asterisk (*, hex 0x2A) followed by two
ASCII characters representing the hexadecimal value of the checksum.
Parameter
Example
Contents
Start
$GPGGA
Message Identifier. Input messages begin at MID 100
Payload
<Data>
Message specific data. Refer to a specific message section for
<data>...<data> definition
Checksum
*CKSUM
CKSUM is a two-hex ASCII character. Checksums is required in all
input messages
End
<CR> <LF>
Each message is terminated using Carriage Return (CR) Line Feed
(LF) which are \r\n. Because \r\n are not printable ASCII characters,
they are omitted from the example strings, but must be sent to
terminate the message and cause the receiver to process that input
message
All fields in all proprietary NMEA messages are required, none are optional and are comma
delimited
In some numeric fields representing a single data element, leading zeros before a decimal are
suppressed. A single "0" character preceding the decimal point is maintained. In compound
numeric structures (such as LAT or LONG), leading zeros are suppressed only on the leftmost
element Trailing zeros are not suppressed
NOTE