Data Format For Hp-Ib Transfer - HP 54501A Programming Reference Manual

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