HP 54501A - Data Format for HP-IB Transfer

D3ta
Format for
There
are
four
formats
for
transferring
waveform
data
over
the
HP-IB.
H
P-l
B
Transfer
These
formats
are WORD,
BYTE,
COMPRESSED,
and
ASCII.
WORD, BYTE,
and
COMPRESSED
formatted
waveform
records
are
transmitted
using
the
arbitrary
block
program
data format
specified
in
IEEE
488.2.
ASCII
format
block
data does
not use
a
block
header.
When
you
use
this
format,
the
ASCII
character
string
"#S <
DD...D
>"
is
sent before
the
actual
data.
The
8
indicates
how
many
< D
>
's
will
follow.
The
<
D
>
's
are
ASCII
numbers,
which
indicate how
many
data
bytes
will
follow.
For
example,
if
512
points
were
acquired
the
Block
Header
"#800000512"
would
be
sent.
The
8
indicates
that
eight length
bytes follow,
512
indicates
that
512
data
bytes (binary)
follow.
WORD
Format In
the WORD
format
the
number
of data
bytes
is
twice
the
number
of
words
(data
points).
The
number
of
data
points
is
the
value
returned
by
the
:WAVEFORM:POINTS?
query.
The
number
of
data
bytes
is
followed
by
a
sequence
of
bytes representing
the
data
points,
with the
most
significant
byte
of
each
word transmitted
first.
In
this
format
the
data
is
shifted
so
that
the
most
significant bit
after
the
sign bit
contains
the
most
significant
bit
of
the
data.
If there
is
a
hole in the
data,
it
will
be
represented
by the
16-bit
value of
-1.
The
range
of data
in
the WORD
format
is
from
0
to
32640.
WORD
format
is
useful in
applications
where
the
information
is
read
directly
into
an
integer
array
in a
controller.
Word
and ASCII
formatted
data
returns
the
most accurate
data
values.
HP
54501A
Programming
Waveform Subsystem
17-5