Digitize Command - HP 54501A Programming Reference Manual

Digitize
Command
The
ACQUIRE
and
WAVEFORM
subsystems are subsystems that affect
the
DIGITIZE
command.
The
DIGITIZE
command
is
used to capture
a
waveform in
a
known format which is
specified by the
ACQUIRE
subsystem.
When the
DIGITIZE
command
is
sent to an instrument, the
specified channel signal
is
digitized with
the current
ACQUIRE
parameters.
To obtain waveform data,
you must
specify
the
WAVEFORM parameters for the waveform data prior to sending the
:WAVEFORM:DATA?
query.
The number of data points comprising
a
waveform
varies according
to the
number requested
in the
ACQUIRE
subsystem.
The ACQUIRE
subsystem determines the number of data points, type of acquistion, and
number of averages used
by
the
DIGITIZE
command.
This
allows you to
specify exactly what the
digitized information will
contain. A typical
setup
is:
OUTPUT 707;'
OUTPUT 707;'
OUTPUT
707;'
OUTPUT 707;'
OUTPUT
707;'
OUTPUT 707;'
OUTPUT 707;'
OUTPUT 707;
":ACQUIRE:TYPE AVERAGE"
<
terminator >
":ACQUIRE:COMPLETE 100"
<
terminator
>
":WAVEFORM:SOURCE
CHANNELl'
< terminator >
":WAVEFORM:FORMAT ASCII"
< tenninator>
":ACQUIRE:COUNT 4"
< terminator >
":ACQUIRE:POINTS
500"
< terminator >
":DIGmZE CHANNELl"
< terminator>
":WAVEFORM:DATA?"
<
terminator >
This setup places the instrument into the average mode with four
averages
and defines the data record to be 500 points. This means that when the
DIGITIZE
command
is
received, the waveform will not be stored into
memory until 500 points have been averaged
at least four times.
After
receiving the :WAVEFORM:DATA?
query, the instrument will
start
passing the waveform information when addressed
to talk.
Digitized
waveforms are passed from the instrument to the controller by
sending
a
numerical representation of
each
digitized
point.
The format of
the
numerical representation
is
controlled with
the
:WAVEFORM:FORMAT
command and may be selected
as
ASCII,
WORD, BYTE, or
COMPRESSED.
Introduction to Programming an Oscilloscope
HP 54501A
1-20
Programming