Agilent Technologies 8510C, Operating And Programming Manual

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Programming Examples
can b e more than one GPIB bus in a computer system. The select co de
allo ws y ou to access m ultiple GPIB busses indep enden tly .)
2. The computer sends the command \PLOP", along with the t w o-digit
instrumen t address n um b er (05).
3. All instrumen ts on the bus see the \PLOP" command. But only the device
set to address 05 with accept the command and p erform it.
(In this example, a plotter set to address 05 w ould p erform the PLOP
command, whic h plots a list of net w ork analyzer op erating parameter
v alues.)
Devices on the net w ork analyzer's system bus only use a t w o-digit address. A
\bus select co de" is not needed b ecause the net w ork analyzer is designed with
only one system bus. When y ou en ter the addresses of system bus devices (in
the 8510C address men u), only t w o digits are required.
Ho w pass-through w orks. Assume for no w that the system bus address (under 4
LOCAL
5
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
SYSTEM BUS ) is still set to 17. Also assume that y ou ha v e selected a prin ter of the system bus
with the ADDRPASS 01; command.
Under these conditions, the net w ork analyzer will accept an y command sen t to address 717.
When suc h a command is receiv ed, the analyzer passes it to the system bus, to the device at
address 01.
F or example:
OUTPUT @Nwa;"ADDRPASS 01;" ! Select address 01 for pass through commands
OUTPUT @Nwa_systbus; CHR"12" ! Send a form feed command to the printer
Remem b er, \@Nw a systbus;" and \@Nw a systbusdata" represen t the address of the system
bus. Y ou m ust set this up using a statement suc h as:
"ASSIGN @Nwa_systbus TO 717"
If the device is to output ASCI I data, use:
ENTER @Nwa_systbusdata; String$
where String$ is dimensioned to accept the ASCI I string sen t from the device. If the device
on the system bus do es not terminate its output with the CR/LF, then the program m ust
terminate the ENTER op eration.
The sp ecied pass-through address remains in eect un til c hanged b y the programmer.
Instructions and data may b e sen t to the net w ork analyzer GPIB address or to the net w ork
analyzer system bus address in an y sequence. When the net w ork analyzer system bus is
addressed, an automatic system bus `Lo cal' is issued whic h halts all system bus activity and
places the net w ork analyzer in Hold. When the net w ork analyzer GPIB is addressed following
a pass-through, an automatic system bus `Remote' is issued whic h returns con trol of the
system bus to the net w ork analyzer.
The addressed device cannot handshak e to the computer or resp ond to GPIB univ ersal or
addressed commands via the system bus.
13-28 GPIB Programming