ashtech DG14, Reference Manual

Page: 247 / 390

NMEA Commands 227
NMEA Commands
The comma after the header is followed by the ASCII data string and the message
checksum. The checksum is separated from the data string by an asterisk. Both
standard and non-standard NMEA messages use a dollar sign ($) to indicate the
beginning of a message, and both types are terminated with a <CR><LF> delimiter.
GGA, which is a standard NMEA message:
$GPGGA,DATA*CHECKSUM<CR><LF>
The structure of non-standard NMEA messages:
HEADER,MESSAGE ID,DATA*CHECKSUM<CR><LF>
Standard NMEA messages include the message identifier in the header. Non-
standard messages, which have an Ashtech format, have the message identifier in
a separate field. SAT, a non-standard message:
$PASHR,SAT,DATA*CHECKSUM<CR><LF>
The data types that appear in NMEA messages can be integers, real numbers
(decimal), hexadecimal numbers, alphabetic characters, and alphanumeric
character strings.
Data items are separated by commas; successive commas indicate data not available. Two
successive commas indicate one missing data item; three successive commas indicate two missing
items.
See the NMEA 0183 Standard for Interfacing Marine Electronic Navigational Devices for more details
on protocols and message formats.
NME: Enable/Disable All NMEA Messages
$PASHS,NME,ALL,x,OFF
Disable ALL NMEA message types on port x, where x is the output port.
Example
Enter the following command to disable all NMEA messages for Port A.
$PASHS,NME,ALL,A,OFF <Enter>
Enter the following command to disable all NMEA messages for Port B.
$PASHS,NME,ALL,B,OFF <Enter>
You must enter both of the above commands to disable the output of all messages from both ports.
At 10 Hz output rate, a baud rate of 115,000 bps is required to output all the NMEA messages. At
greater output rates, the raw data must be split between the two serial ports, or some of the
messages should be turned off. To receive data at high baud rates (e.g., 115,000), ensure that the
computer has a suitable serial I/O capability. Most newer computers with Pentium or 486 processors
have good enough serial communication to support high data rates.