Product specifications

Crescent Integrator’s Manual 26

OMMUNICATING WITH THE

RESCENT

ECTOR

ODULE

The Crescent Vector features three primary serial ports that may be configured

independently from each other (Ports A, B and C). The ports may be configured for

any mixture of NMEA 0183, binary, and RTCM SC-104 data. The usual data output is

limited to NMEA data messages since these are industry standard.

Note: If you require different data types to be output from the Crescent Vector

simultaneously (such as NMEA and binary or NMEA and RTCM), ensure that the

software used for logging and processing of the data has been designed to

correctly parse the different data types from the single stream of data.

Alternatively, you may also use the three serial ports to separate the different data

types and at different output rates.

NMEA

0183

NTERFACE

NMEA 0183 is a communications standard established by the National Marine

Electronics Association (NMEA) and provides data definitions for a variety of

navigation and related equipment. Such instruments supported include

gyrocompasses, Loran receivers, echo sounders, GPS receivers, and more.

NMEA functionality is virtually standard on all GPS equipment available.

NMEA has an ASCII character format that allows you to read the data via

terminal software on the receiving device (if possible). One second of

example NMEA data from the Crescent Vector follows:

$GPGGA,144049.0,5100.1325,N,11402.2729,W,1,07,1.0,1027.4,M,0,M,,0100*61

$GPVTG,308.88,T,308.88,M,0.04,N,0.08,K*42

$GPGSV,3,1,10,02,73,087,54,04,00,172,39,07,66,202,54,08,23,147,48*79

$GPGSV,3,2,10,09,23,308,54,11,26,055,54,15,00,017,45,21,02,353,45*78

$GPGSV,3,3,10,26,29,257,51,27,10,147,45,,,,,,,,*74

Depending on each manufacturer’s goals for a product, they may have the

need to combine data into custom messages, which allows them to improve

communication and programming efficiency. The standard NMEA standard

provides for manufacturers to define their own custom, proprietary messages

as required. Proprietary NMEA messages are likely to be supported only by

the specific manufacturer. In the case of the Crescent Vector, it’s likely that

you will need to support custom NMEA commands within your application if

you wish to have your software configure the unit on-the-fly.

The Crescent Vector supports a variety of standard and proprietary NMEA

messages. These messages are used to configure the Crescent Vector and

also contain the required information from the Crescent Vector. You may

configure a selection of NMEA 0183 data messages on one port at various

update rates (each message has a maximum update rate) and a different

selection of NMEA 0183 messages with different rates on another port.