Table 7-16
Numeric Argument Format for Commands
Numeric Number
Argument Format Examples
<NR1>
Integers
+1,
2,
-1,
-10
<NR2>
Explicit decimal point
-3.2,
+5.1, 1.2
<NR3>
Floating point
in
+
1.E-2,
1.0E+2,
scientific notation
1.E-2,
0.02E+3
WAVEFORM TRANSFERS
The
instrument
can
transmit
and
receive waveforms. It
can
transfer these waveforms
in
binary, hexadecimal, or
ASCII encoding.
When
sending waveforms to the instru-
ment, the target must
be
one of the numbered reference
memories
(REF4
only for the 2220
and
2221
).
Waveforms
transferred from the oscilloscope to the controller
may
be
from either the current acquisition or one of the numbered
reference memories (again
REF4
for the 2220
and
2221).
The
data source (the memory location from which the
waveform data comes )
and
the data target (the memory
- - location where data sent to the oscilloscope ends
up)
are
selected independently.
Waveform Preamble
The
waveform preamble contains the attributes for the
associated waveform data. These attributes include the
number of points per waveform, scale factors, vertical
offsets, horizontal increment, scaling units,
and
data
encoding.
The
preamble information
is
sent
as
an
ASCII-
encoded string
in
all
cases.
The
exact attributes sent
depend
on
the waveform
and
the acquisition
mode.
A typical response to the preamble query WFMpre? for
a Y (time-implied) acquisition is:
WFM
WFl:"ACQ,
CH1
,0.5V,DC,0.2mS,SAMPLE,
CRV#
1",NR.P:4096,PT.O:122,PT.F:Y,
XMU:0.0E0,XOF:0,XUN:S,XIN:2.0E-6,
YMU:20.0E-3,YOF:-20,YUN:V,ENC:HEX,BN.F:RP,
BYT:1,BIT:8,CRV:CHK;
Options and
Accessories-2230
Operators
A typical response to the preamble query for
an
X-Y
acquisition
is:
WFM
WFl:"ACQ,XY,0.2V,DC,50.0mV,DC,
1.0µS, SAMPLE,
CRV#
4",
NR.P:2048,PT.O:216,PT.F:XY,XMU:8.0E-3,
XOF:0,XUN:S,XIN:20.0E-9,YMU:2.0E-3,YOF:0,
YUN:V,ENC:BIN,BN.F:RP,BYT:1,BIT:8,CRV:CHK;
These replies
are
single
line
messages that
end
with
the selected message terminator
(CR
or CR-LF). With the
GPIB interface,
EOI
(end-or-identify)
is
also sent if that ter-
minator mode
is
selected.
Transferring Waveforms
The
oscilloscope
can
respond with the preamble only,
the curve data only, or the preamble
and
curve data
together.
The
queries to obtain these responses
are,
in
order, WFMpre?, CURVe?,
and
WAVfrm?
For the combined response to WAVfrm?, the preamble
is
separated from the curve data
by
a semicolon
(;).
The
preamble information
is
always formatted
as
ASCII
characters. Waveform (CURVE) data internal to the oscil-
loscope
is
stored
as
8-bit, unsigned integers. Before that
data
is
sent
via
the Communications option, it
is
changed
into
one
of three formats: binary, hexadecimal, or ASCII.
The
resolution of the formatted data points may
be
either
8-bit or 16-bit. Waveform record length
is
1024 data points
for the shortest or 4096 data points for the longest. The
number of bytes that
are
required to transfer data
depends
on
several variables.
See
the NR.Pts description
in
the Waveform Preamble Fields command table for more
information.
The
largest number of curve data bytes ever
needed
to
send
a waveform
is
8192 bytes (for a
4K
record
that
has
two bytes per data point).
Binary Encoding
BINary data
is
transferred
as
unsigned binary integers.
Each
data point
in
the record
is
either 8 bits or, when
averaged,
16
bits. BINary encoding format has the follow-
ing
waveform curve data form:
7-21
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