Tektronix 2221 - Page 170

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Appendix
B -
2221
Operators
A : The data channel for source and target for waveform
transfers is designated using the REFERENCE
WAVEFORM commands ( see DATA CHAnnel ) Either
channel of
the
acquisition or
Save Ref
memory
may
be retrieved from the oscilloscope . Waveform data
may be sent to either channel of a targetted Save Ref
memory
( see DATA
TARget
)
.
A : Flow
control must be used
when
sending
waveform
data to the oscilloscope at the higher baud rates . That
is because the input data buffer is only 160 characters
long and
it fills up
before
the
processor is
ready to
handle the
input
.
Because of
the
nature
of
binary
data , flow
control can not
be used
to
reliably
send
or
receive binary - encoded curve data . Use either HEX or
ASCII encoding instead . HEX - coded waveform data
requires fewer characters to be transferred than
ASCII - coded waveform data , and therefore is faster
than ASCII format . Also , parity must be disabled with
the
PARAMETERS
switch
setting for
binary
data
transfers . That setting has to be made before the
instrument is
turned on ; at
power
- on is
the only
time
the switch is
read .
Q : What is the purpose of the external clock ?
A : The external clock can be used to acquire signals that
change
too
slowly for the
normal
calibrated SEC
/ DIV
settings ( for example , one sample every hour ) .
Another use is to synchronize the 2230 so that
samples are
done on
selected events .
U
Q :
What
is the
size of
the
oscilloscope's data
output
buffer
?
!
Q : Can you re - arm Single Sweep via the communication
option ?
A :
The output buffer is about 1,000 characters .
Q :
Why do I sometimes get bad curve data when I
operate the DSO in the Repetitive Store Mode ?
A : The Single Sweep function may be armed using the
SGLSWP ARM command . Single Sweep may also be
queried to determine the state of the Single Sweep
function
(
ARM or
DONE ) .
U d
Q :
What
is
the
maximum
sensitivity in
digital
storage ?
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A : It is 2 mV / division , the same as in nonstore mode .
A : This
problem is
caused by not
allowing
enough
sweeps to occur
to fill the
entire
waveform record
.
Repetitive
Store
Mode ( random
equivalent
- time
sampling ) depends on the probability of filling the
waveform
record in a
specified
number
of
sweeps .
The more
sweeps that are used
to sample an
input
signal , the more probable it is that the waveform
record will be filled
when the
waveform is
asked
to
be
transferred . If
you
receive bad
curve
data
,
allow more
sweeps
to
occur
before requesting the
waveform
from
the
oscilloscope
.
Q : Can I compress , expand , or reposition the stored
waveforms
?
Cu
you
must
A : The
2230 has
commands
for
reformatting
a
target
reference waveform ; the 2220 and 2221 do not .
Q : What is the maximum expansion / compression factor
for stored waveforms with the 2230 ?
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One way
to do this
is to set
the
number of
sweeps
( via either
the
oscilloscope's menu
controls
or a
command
message
) to
a value
several
times
larger
than
the
number of
sweeps
needed for a 50 %
probability of filling the record ( see Controls ,
Connectors , and Indicators-
Section
3 of
the
Operators manual ) . Also , you can set RQS and OPC
on . Then ,
when the
specified
number
of
sweeps
have
been acquired , the oscilloscope will issue a single
SRQ ( service request ) . When the controller software
determines that an
the end - of -
acquisition OPC state
caused
the service
request , it
can
request
the
curve
data
,
A : Vertically , the reformat target waveforms may be
expanded or
compressed
by a factor
of ten from
their
acquired VOLTS / DIV setting . Horizontally , the X10
Magnification feature may be turned on for the
reformat target waveforms .
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Q : Can I return a reformatted waveform back to its
original settings ?
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Q : When operating in ALT or CHOP Vertical Mode , how
do I
designate from
which
channel
of
the
acquisition
or reference memory the waveform data is retrieved ?
How do I designate in which channel of a reference
memory
the
waveform data is stored
when
sending
waveforms to
the
oscilloscope ?
A : Yes . Query the BASegain to determine the acquired
volts / div setting and set the VGAin to that setting . To
return to the original vertical position , set VPOsition to
; turn HMag off to regain the acquired sec / div
setting
.
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