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MX 420 Installation and Service Manual
MX420 NMEA 0183 Sentences
The NMEA Standard provides for asynchronous transmission, with a single
Talker
and
multiple
Listeners
per line. Typical use includes information transfer from electronic
positioning and navigational devices to autopilots, plotters, terminals, printers, etc.
The NMEA 0183 Standard uses an 8 bit ASCII block oriented protocol, that is not
compatible with the NMEA 0180 simple format or the NMEA 0182 complex format due to
differences in data format, baud rate and parity bits.
Data Format
Data are transmitted in different sentences, each containing one or more data fields. A
field consists of a string of characters immediately preceded by a “,” (comma) charac-
ter, except for the first (address) field which is preceded by “$”, indicating the begin-
ning of a new record. Hex 0D 0A <CR>< LF> - end of sentence - must follow the last
field in each sentence.
The data fields are identified only by their position within the sentence as deter-
mined by the field delimiters (comma). Numerical data fields within a sentence may
vary in length from one sentence to another, depending on the precision available.
Data field position is therefore determined only by counting “,” (commas) rather than
counting the total number of characters from the beginning of the sentence.
The last data field is not followed by a comma delimiter. When a checksum is used,
the last data field is followed by an asterisk “*”, indicating that the checksum
follows. The checksum is the absolute value calculated by
exclusive -OR’ing the 8 data bits (no start bits or stop bits) of each character in the
sentence between, but excluding “$” and “*”. The hexadecimal value of the most
significant and least significant 4 bits of the result are converted to two ASCII
characters (0- 9, A- F) for transmission. The most significant character is transmit-
ted first.
Summary of Contents for MX420
Page 1: ...Installation Service Manual MX420 Navigation System ...
Page 5: ......
Page 8: ...1 MX 420 Installation and Service Manual List of Components SECTION 1 LIST OF COMPONENTS ...
Page 9: ...MX 420 Installation and Service Manual List of Components 2 ...
Page 15: ...MX 420 Installation and Service Manual List of Components 8 ...
Page 17: ...MX420 Installation and Service Manual Technical Specifications 10 ...
Page 24: ...17 MX420 Installation and Service Manual SECTION 3 MECHANICALAND INSTALLATION DRAWINGS ...
Page 25: ...18 MX420 Installation and Service Manual ...
Page 32: ...25 MX420 Installation and Service Manual SECTION 4 ELECTRICALINSTALLATION DRAWINGS ...
Page 33: ...26 MX420 Installation and Service Manual ...
Page 49: ...42 MX420 Installation and Service Manual ...
Page 57: ...50 MX 420 Installation and Service Manual SECTION 5 INSTALLATION NOTES ...