Quantum Data 802BT - Manual (Page 112)

102 Chapter 7 Using GPIB Interface
Sending commands and queries
The generator parses command lines one at a time. Command lines must be terminated
with a carriage return (<cr>).The generator immediately echoes each character as it is
received and places it in a command line buffer. This buffer currently has room for a total of
256 characters. If more than 256 characters are sent before sending a <cr>, then the
following response will be given:
Buffer overflow<cr><lf><cr><lf>R:\>
Upon receiving a carriage return, the generator immediately echoes the <cr> and follows it
with a line feed (<lf>). The generator then parses the command line and initiates whatever
processing is implied. The generator then responds with one of the following four
responses depending on the condition:
Command invalid<cr><lf><cr><lf>R:\>
<message1><cr><lf><message2><cr><lf>...<messageN><cr><lf><cr><lf>R:\>
Execution error: <nnnn><cr><lf><cr><lf>R:\>
R:\>
Where <cr> and <lf> are the carriage return and line feed characters, respectively.
Note: Handshaking routines should only look for > and not R:\>. In the future, the R:\ part
of the prompt may change (for example, may be expanded to indicate the current path).
Bench-top generators output the following prompt on their serial port after finishing the
power-on procedure.
R:\>
This feature allows ATE systems to know when the generator is ready.
Sending multiple commands and queries per line
You cans send multiple commands and queries per line by separating each command or
query with a semi-colon (;) character. For example:
HTOT 900; ALLU
The response to multiple queries will be a series of data elements separated by
semi-colons (;). For example, with the VGA_m3 format loaded, the following command
string will produce the response shown.
HRES ?; VRES ?; VTOT ?
640;480;525
Normally, all of the commands on a command line associated with a single command
terminator are read as a single command message without regard for execution or
completion order. However, by inserting the *WAI command, you can force the generator