ashtech GG Surveyor, Reference Manual

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Command/Response Formats 129
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NMEA Data Message Commands
The NMEA message commands control all query and set commands related to
NMEA format messages and miscellaneous messages in a NMEA style format. All
standard NMEA message are a string of ASCII characters delimited by commas, in
compliance with NMEA 0183 Standards version 2.1. All non-standard messages are a
string of ASCII characters delimited by commas in the Ashtech proprietary format.
Any combination of these messages can be output through different ports at the same
time. The output rate is determined by the $PASHS,NME,PER command and can be
set to any value between 0.2 and 999 seconds.
Maximum NMEA update rate is dependent on receiver options.
For each NMEA message type there is a set command, a query command and a
response message. The set command is used to continuously output the NMEA
response message at the period defined by the $PASHS,NME,PER command. The
query will output a NMEA response message only once.
Set Commands
The general structure of the NMEA set commands is:
$PASHS,NME,str,x,s <Enter>
where x is the serial port to which response message should be sent (A, B, or C), and
s is either ON or OFF. ON will enable the message and OFF will disable the message.
The str is a 3 character strings that depicts the NMEA message to be output. The
available strings are:
AIM, GGA, GLL, GRS, GSA, GSN, GST, GXP, LTN, MSG, POS, RMC,
RRE, SAT, TCM, TTT, VTG, and ZDA
When a set command is sent correctly, the receiver will send a $PASHR,ACK
(command acknowledge) message. If the command is sent incorrectly or the syntax is
wrong, the receiver will sent a $PASHS,NAK (command not acknowledged)
message. Once acknowledged, the receiver will output the corresponding NMEA
data message at the interval defined by the $PASHS,NME,PER command, unless a
necessary condition for the message to be output is not present. For example, the
GGA message will not be output unless a position is being computed.
To disable all set NMEA message, use the $PASHS,NME,ALL command.
To see what NMEA messages have been enabled, use the $PASHQ,PAR command.