Kongsberg Simrad TV80, Справочное руководство

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406388/F
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NMEA
The National Marine Electronics Association (NMEA) has defined communication
standards for maritime electronic equipment. The TV80 Catch Monitoring Software
supports these standards for communication with external sensors and peripheral systems.
The most common standard is NMEA 0183. The National Marine Electronics
Association describes it as follows:
The NMEA 0183 Interface Standard defines electrical signal requirements, data
transmission protocol and time, and specific sentence formats for a 4800-baud serial
data bus. Each bus can have only one talker but many listeners.
National Marine Electronics Association
For more information about the National Marine Electronics Association and the NMEA
0183 standard, refer to the organization's web site at:
• http://www.nmea.org
Related topics
About NMEA and standard datagram formats, page 316
Datagram formats, page 315
NMEA sentence structure
A sentence structure is defined by NMEA to establish the communication between two
units. Most other datagram formats are designed using the same, or a similar, structure.
The following provides a summary explanation of the approved parametric sentence
structure:
$aaccc,c-c*hh<CR><LF>
1
$
This character (Hex: 24) is used to identify the start of a sentence.
2
aaccc
This is the address field. The first two characters (aa) identify the talker ID , while
the last three characters are the sentence formatter mnemonic code identifying the
data type and the string format of the successive fields.
3
,
The comma (Hex: 2C) is used as a field delimiter . This character starts each field
except the address and checksum fields. If it is followed by a null field, it is all that
remains to indicate that there are no data in the field.
4
c-c
This is the data sentence block . This is a series of data fields containing all the data
to be transmitted. The data field sentence is fixed and identified by the sentence
formatter in the address field. Data fields may be of variable length, and they are
preceded by the field delimiter.
Datagram formats