USGlobalsat EM-406a - Manual (Page 9)

EM-406a
Specifications are subject to be changed without notice.
Page 9 of 13
Version 1.4.1
Name Example Units Description
Message ID $GPVTG VTG protocol header
Course 309.62 degrees Measured heading
Reference T True
Course degrees Measured heading
Reference M Magnetic
Speed 0.13 knots Measured horizontal speed
Units N Knots
Speed 0.2 Km/hr Measured horizontal speed
Units K Kilometers per hour
Checksum *6E
<CR><LF> End of message termination
■
NMEA Input Command
A.) Set Serial Port ID:100 Set PORTA parameters and protocol
This command message is used to set the protocol (SiRF Binary, NMEA, or USER1) and/or the
communication parameters (baud, data bits, stop bits, parity). Generally, this command is utilize to
switch the GPS module back to SiRF Binary protocol mode, where an extensive message commands
are readily available. In example, whenever users are interested in altering navigation parameters, a
valid message sent and is receive by the recipient module, the new parameters will be stored in
battery backed SRAM and then the receiver will restart using the saved parameters.
Format:
$PSRF100,<protocol>,<baud>,<DataBits>,<StopBits>,<Parity>*CKSUM
<CR><LF>
<protocol> 0=SiRF Binary, 1=NMEA, 4=USER1
<baud> 1200, 2400, 4800, 9600, 19200, 38400
<DataBits> 8,7. Note that SiRF protocol is only valid f8 Data bits
<StopBits> 0,1
<Parity> 0=None, 1=Odd, 2=Even
Example 1: Switch to SiRF Binary protocol at 9600,8,N,1
$PSRF100,0,9600,8,1,0*0C<CR><LF>
Example 2: Switch to User1 protocol at 38400,8,N,1
$PSRF100,4,38400,8,1,0*38<CR><LF>
**Checksum Field: The absolute value calculated by exclusive-OR the 8 data bits of each character
in the Sentence, between, but, excluding “$” 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. First, the most significant character is transmitted.
**<CR><LF> : Hex 0D 0A
B.) Navigation initialization ID:101 Parameters required for start
This command is used to initialize the GPS module for a “Warm” start, by providing real-time position