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COMMAND REFERENCE 4 - 55
Description:
The FETCh? queries are part of the measurement instruction set. They return the
signal characteristic from the last initiated measurement, as specified by the
<measure function> part of the query header.
An initiate command must precede a FETCh? query. The initiate command may
be given either explicitly as INITiate[:IMMediate] command, or explicitly by a
READ? or MEASure? query. When the acquisition is still in progress, the
response to a FETCh? query does not become available until the acquisition is
completed. In such a case, no error is reported. Execution of INITiate[:IMMediate]
and FETCh? is equivalent to the execution of the READ? query.
A FETCh? query may also return a signal characteristic from a valid acquisition
result that is stored in a TRACe memory element.
Example: Send
→ FETCh:AC? (@M2_3) Fetches AC- RMS of the M2_3 trace.
A FETCh? query allows the same parameter sets as the corresponding
MEASure? and CONFigure instructions. Their use distinguishes from these
instructions in that they only serve to specify the desired result from a FETCh?
query. They don’t affect the instrument settings. They may also be sent for
reasons of compatibility with a preceding CONFigure or READ? instruction.
When the <measure_function> part of the FETCh? query header is defaulted, the
characteristic as specified by the last executed FETCh?, READ?, or MEASure
query is returned. When such a query is not executed since the last power on
cycle, the measure function VOLTage:DC is assumed by the oscilloscope.
The default :VOLTage node specifies that the requested characteristic relates to
the voltage component of the signal. For example, the rise time or the frequency
of the voltage.
Restrictions:
(1) A FETCh? query may be executed only when the oscilloscope is in the
digital mode (INStrument:SELect DIGital). The digital mode is selected after
*
RST. Executing this query when the instrument is in the analog mode
generates execution error -221,"Settings conflict; Digital mode required".
(2) A FETCh? query may not operate on a TRACe memory element that has
been modified since the last executed INItiate[:IMMediate], READ?, or
MEASure? command. Otherwise execution error -230,"Data corrupt or
stale" is generated.