Nmea 0183 Messages, Definitions; Message Description - Simrad ITI TRAWL SYSTEM - SERIAL DATA COMMUNICATION REV A Instruction Manual

6 NMEA 0183 MESSAGES, DEFINITIONS

Message description

Note
857-164777 / A
Messages transmitted and received on serial lines or Ethernet are
all based on the NMEA 0183 data format protocol.
The main characteristics are as follows:
• RS-422A asynchronous serial line
• 4800 baud
• 8 data bits
• No parity
• One or more stop bits
• All data coded in ASCII code
• Optional "X-OR" checksum
All messages start with either; "$" or "@".
Telegrams starting with "$" do fully comply with the NMEA 0183
data format protocol.
• All other telegrams are in accordance with an old proprietary
"Simrad standard." They start with @, but otherwise they
follow the main characteristics listed below.
• The next two letters (Talker identifier) indicate which system
is transmitting the messages. Simrad ITI System uses II as a
talker identifier.
• Thenextthree lettersindicate thetype ofmessage. Thetelegram
may consist of many data fields separated by commas. A field
may be empty, and then only the separating commas are
transmitted, also called nullfields.
• Each message ends with <cr> (Carriage Return) and <lf> (Line
Feed). For all message starting with "$" the checksum *hh is
included in compliance with version 2.20 of the NMEA 0183
standard, - no checksum on "@" sentences.
Throughout this document, all telegrams with II as the Talker
identifier, and telegrams with the proprietary code PSIM, are
originated by ITI and transmitted to other equipment. All
telegrams with other Talker identifiers are received by ITI from
external equipment.
Below you will find the message description for ITI topside
software version 5.30 or above. The different types of telegrams
are not listed in consecutive order.
The *hh check sum, <cr> carriage return and <lf> line feed are
not described for each sentence.
Instruction manual
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