USGlobalsat ER-112 - Manual (Page 11)

ET-112
Specifications are subject to be changed without notice.
Page 11 of 15
Version 1.3
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
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,,,,,*CKSUM
0=SiRF Binary, 1=NMEA, 4=USER1
1200, 2400, 4800, 9600, 19200, 38400
8,7. Note that SiRF protocol is only valid f8 Data bits
0,1
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
Example 2: Switch to User1 protocol at 38400,8,N,1
$PSRF100,4,38400,8,1,0*38
**Checksum Field: The absolute value calculated by exclusive-OR the 8 data bits of each character
in the Sentence, between, but, excluding “$” 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.
** : 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
（
in X, Y, Z coordinates), clock offset, and time. This action enables the GPS receiver to search for the
necessary satellite signals at the correct signal parameters. The newly acquired and stored satellite
data will enable the receiver to acquire signals more quickly, and thus, generate a rapid navigational
solution.
When a valid Navigation Initialization command is receive, the receiver will restart using the input
parameters as a basis for satellite selection and acquisition.