Tektronix 2221 - Page 98

U
Options and
Accessories -
2221
Operators
CURVE
<
space
>
% <
Binary Count MSB > <
Binary
Count LSB > < Binary Data > < Checsum > < Termi
nator >
Table 7-17
Typical 8 - Bit Binary - Encoded Waveform Data
C
GPIB EOI
( 1 = Asserted )
Where :
Byte
Contents
Decimal
CURVE
is a literal
string
indicating that
curve
data
follows
.
1
2
3
4
с
U
R
ย
%
is used as a header character
to
show the
start of a
binary
block ,
67
85
82
86
69
32
37
น
5
6
E
<
SP >
% 7
<
Binary
Count
MSB >
8
is the most
significant
byte
of
the two - byte
Binary Count .
Binary Count is the length of
the
waveform , in
bytes ,
plus
the one - byte
checksum .
< Bin Count MSB >
< Bin
Count USB >
160
01a
9
d
10
11
1st Pt
2nd Pt
dz
<
Binary
Count
LSB >
is the least - significant byte of
the Binary Count
.
<
Binary
Data
>
4105
4096th Pt
d4096
is made up
of 256 , 512 ,
1024 ,
2048 , or
4096 data
points .
Each data
point is
either
a
1
byte ( 8 bits ) or 2 - byte ( 16 bits )
representation
of
each
digitized
value .
4106
<
Checksum >
chk
1
1 When
TERM- EOI
41076
41089
< CR >
< LF >
13
10
1
بل
<
Checksum >
( 100116 or 4097
)
is the
two's -
complement of the
modulo
256 sum
of
the
preceding data
bytes
and the
binary count .
The Checksum
is
used
by
the
controller
program
to verify that all data values
have
been
received
correctly .
bAll RS - 232 - C or GPIB with TERM –
LF / EOI .
CRS - 232 - C with TERM
=
CR - LF .
Table
7-15
illustrates the
data transferred
for a
4096 - point , 8 - bit , binary - encoded waveform . The waveform
data -
point values vary
with the
signal
amplitude
.
C
C
1. The curve header is " CURVE #H " instead of
"
CURVE %
" .
Table 7-16
illustrates
the
data
transferred for a
4096 - point , 16 - bit ( averaged ) , binary - encoded waveform .
2. Each data point is two ASCII hexadecimal characters
for 8 - bit
transfers
and four
ASCII
hexadecimal
characters
for 16 -
bit
transfers .
Hexadecimal
Encoding
3. The byte count is sent as four successive ASCII hex
adecimal
characters
, but the
value of the
byte count is
identical to a
comparable
BINary
transfer
.
With
HEXadecimal waveform
data encoding ,
characters
representing an 8 - bit or 16 - bit data point are sent in a
fixed
ASCII
hexadecimal
format .
There are no
delimiters
(
commas
)
between
data
points . Data format
is very similar
to
BINary
format ,
with
the
following
exceptions
:
C
C
4. The
checksum
is sent as
two
successive ASCII
hex
adecimal characters .
7-22