Holux M-9129 -, Specification

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GPS Engine Board M-9129
- 10 -
5.3 MTK NMEA Packet Format
Preamble TalkerID PktType Datafield * CHK1 CHK2 CR LF
Maximum packet length is restricted to 255 bytes
Field Length Type D
Preamble 1 byte Character “$”
TalkerID 4 byte Character string “PMTK”
PktType 3 byte Character string
“000”to “999”, an
identifier used to tell
the decoder how to
decode the packet
DataField Variable
“, ”must be inserted
ahead each data
filed to help the
decoder process
the Data Field
* 1 byte Character
The star symbol is
used to mark the
end of Data Field
CHK1
CHK2
2 byte Character string
checksum of the
data between
Preamble “, ”and “*”
CR, LF 2 byte Binary data
used to identify the
end of a packet