USGlobalsat EM-408 - Manual (Page 10)

EM-408
Specifications are subject to be changed without notice.
Page 10 of 14
Version 1.4.1
■ 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 （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.
Format
$PSRF101,<X>,<Y>,<Z>,<ClkOffset>,<TimeOfWeek>,<WeekNo>,<chnlCount>,<ResetCfg>
*CKSUM<CR><LF>
<X> X coordinate position
INT32