ashtech DG14, Reference Manual

Page: 109 / 390

Receiver Commands 89
Receiver Commands
Receiver commands allow you to change or query the status of various operating
parameters such as elevation mask, antenna altitude, position mode, etc. In this
context, set commands are used to change the DG16’s operating parameters.
Query commands prompt the DG16 to output status messages for parameter
settings and receiver operation.
If an invalid set or query command is issued, a “not acknowledged” (NAK) response
is output:
$PASHR,NAK*30
Set command messages can be sent through serial port. When the DG16 receives
a valid set command message, it returns an "acknowledged" (ACK) message:
$PASHR,ACK*3D
The DG16 returns a NAK message if the command is invalid. For example, the set
command
$PASHS,SAV,Y<Enter> instructs the DG16 to save user-entered
operation parameters; the DG16 returns $PASHR,ACK*3D to acknowledge that
the command was valid and the instruction was carried out. The set command
$PASHS,SAV<Enter> is incomplete, and would cause the DG16 to flag it as an
invalid command by responding with a “not acknowledged” response:
$PASHR,NAK*30.
The set command message structure is as follows:
“Header,Command ID,<Command Parameters>*Checksum<Enter>”
The header field always contains $PASHS . The command identifier field contains
a three character string and is followed by the command parameters. The checksum
is strictly optional. All set commands are terminated with an
<Enter> or <CR><LF>
keystroke. All command string elements between the dollar sign ($) and the asterisk
(*), including the command parameters, are comma delimited; that is, the header,
the ID string, and the individual command parameters are separated by commas.
Enter the following set command to set the HDOP mask value:
$PASHS,HDP,6<Enter>
Query commands are used to request current GPS information and receiver status
information such as baud rate settings, position information, and tracking
information. Query command messages can be sent to either of the DG16’s serial
ports. Most query commands allow you to designate the port from which the
response message is sent. The DG16 acknowledges a valid query command
message by sending the requested response message through the specified port.
If the port is not specified in the query command, the response is sent from the
same port which received the query. The requested information is sent once each
time the command is issued and is not repeated.