Linx Technologies RXM-GPS-SR - Manual (Page 7)

Page 13 Page 12
NMEA INPUT MESSAGES
The following outlines the serial commands input into the module for
configuration. By default, the commands are input at 9,600bps, 8 data bits, no
parity, and 1 stop bit. SiRF binary commands are input at 38,400bps, 8 data bits,
no parity, and 1 stop bit.
All fields in all proprietary NMEA messages are required; none are optional. All
NMEA messages are comma delimited.
The table below outlines the message identifiers supported by the module.
Name Example Description
Start Sequence $PSRF
Message ID <MID>
Message Identifier consisting of three numeric
characters. Input messages begin at MID 100.
Payload DATA Message specific data.
Checksum CKSUM
CKSUM is a two-hex character checksum as
defined in the NMEA specification, NMEA-0183
Standard For Interfacing Marine Electronic Devices.
Checksums are required on all input messages.
End Sequence <CR><LF>
Each message must be terminated using Carriage
Return (CR) Line Feed (LF) (\r\n, 0x0D0A) to cause
the receiver to process the input message. They are
not printable ASCII characters, so are omitted from
the examples.
Message MID Description
SetSerialPort 100 Set PORT A parameters and protocol
NavigationInitialization 101 Reset the modules
Query/Rate Control 103
Query standard NMEA message and/or set
output rate
LLANavigationInitialization 104 Reset the modules
Development Data On/Off 105 Development Data messages On/Off
PowerManagement 200 Sets the power performance of the receiver
StaticNavigation 202 Sets static navigation On/Off
Table 10: Serial Data Structure
Table 11: Message ID Values
RMC – Recommended Minimum Specific GNSS Data
The table below contains the values for the following example:
$GPRMC,053740.000,A,2503.6319,N,12136.0099,E,2.69,79.65,100106,,,A*53
VTG – Course Over Ground and Ground Speed
The table below contains the values for the following example:
$GPVTG,79.65,T,,M,2.69,N,5.0,K,A*38
Name Example Units Description
Message ID $GPRMC RMC protocol header
UTC Time 53740 hhmmss.sss
Status A A=data valid or V=data not valid
Latitude 2503.632 ddmm.mmmm
N/S Indicator N N=north or S=south
Longitude 12136.01 dddmm.mmmm
E/W Indicator E E=east or W=west
Speed over ground 2.69 knots TRUE
Course over ground 79.65 degrees
Date 100106 ddmmyy
Magnetic Variation degrees Not Available, Null Field
Variation Sense E=east or W=west (Not shown)
Mode A A=autonomous, D=DGPS, E=DR
Checksum *53
<CR> <LF> End of message termination
Table 8: Recommended Minimum Specific GNSS Data Example
Table 9: Course Over Ground and Ground Speed Example
Name Example Units Description
Message ID $GPVTG VTG protocol header
Course over ground 79.65 degrees Measured heading
Reference T TRUE
Course over ground degrees Measured heading (N/A, Null Field)
Reference M Magnetic
Speed over ground 2.69 knots Measured speed
Units N Knots
Speed over ground 5 km/hr Measured speed
Units K Kilometer per hour
Mode A A=autonomous, E=DR
Checksum *38
<CR> <LF> End of message termination