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This chapter covers the formats and content of the serial port commands through
which the G12 receiver is controlled and monitored. These serial port commands
set receiver parameters and request receiver status information and other data.
Use Evaluate™ software or any other standard serial communication software to
communicate with the receiver. Note that the baud rate and protocol of the computer
COM port must match the baud rate and protocol of the receiver port for commands
and responses to be successfully transmitted and received. The communication
protocol is 8 data bits, 1 stop bit, and no parity.
All messages sent by the user to the receiver are either “Set” command messages
or “Query” command messages. Set commands generally change receiver
parameters and initiate data output. Query commands generally request receiver
status information. All set commands begin with the string $PASHS; all query
commands begin with $PASHQ. $PASHS and $PASHQ are the message headers.
They are required for all set or query commands. All commands must end with an
<Enter> or <CR><LF> (Carriage Return/Line Feed) keystroke in order to send the
command to the receiver. If desired, an optional checksum may precede the
<Enter> characters. All response messages also end with <Enter> or <CR><LF>
characters. Please note that some messages are functional only if the appropriate
option is installed.
When a command is sent to one of its serial ports, the G12 responds by outputting
a message indicating the acceptance or rejection of the command. In the case of
query commands, the G12 either outputs a response message containing data
relevant to the query or sends a “NAK” response, indicating that the query command
was invalid. All G12 response messages begin with the string $PASHR, including
status messages that are set for output at regular intervals from either of the G12’s
serial ports.
G12RevD.book Page 47 Tuesday, April 2, 2002 4:33 PM
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