HP 54501A - Page 37

Multiple
Queries
You can
send
multiple
queries
to
the
instrument
within
a single
program
message,
but
you
must
also
read
them
back within
a
single
program
message.
This
can
be
accomplished
by
either
reading
them
back
into
a
string
variable
or
into
multiple
numeric
variables.
For
example,
you
could
read
the
result of
the
query
:TIMEBASE:RANGE?;DELAY? into
the
string
variable
Results$ with
the
command:
ENTER
707;Results$
When
you
read
the
result
of
multiple
queries
into
string
variables,
each
response
is
separated
by a
semicolon. For
example,
the
response
of the
query
:TIMEBASE:RANGE?;DELAY?
with
HEADER
and
LONGFORM
on
would
be:
:TIMEBASE:RANGE
<range_setting>;:TIMEBASE:DELAY
<delay_setting>
If
you
do
not need
to
see
the
headers
when
the
numeric
values
are
returned,
then
you
could
use
following
program
message
to read
the
query
:TIMEBASE:RANGE?;DELAY? into
multiple
numeric
variables:
ENTER
707;Resultl,Result2
Note
Instrument
Status
When
you
are
receiving
numeric
data into
numeric
variables,
the
headers should
be
turned
off. Otherwise
the headers
may
cause
misinterpretation
of
returned
data.
Status
registers
track
the
current
status
of
the
instrument.
By
checking
the
instrument status,
you can
find
out
whether
an operation
has
been
completed,
whether
the
instrument
is
receiving
triggers,
and
more.
The
chapter
"Message
Communication
and
System
Functions"
explains
how to
check
the
status of
the
instrument.
HP
54501A
Programming
Introduction
to
Programming
an
Oscilloscope
1-19