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USING THE COMBISCOPE INSTRUMENTS 3 - 15
READ:FREQuency? Starts the acquisition and returns the measured
frequency.
READ:FREQuency? Starts a next acquisition and returns the new
frequency result.
READ:FREQuency? Etc.
3.3.6 Multiple characteristics from a single acquisition.
It is often necessary to determine several signal characteristics from the last
acquired waveform. Starting a new acquisition, as READ? and MEASure? do, is
undesired. For that purpose, READ? is broken down into two additional
instructions, which are the INITiate[:IMMediate] command and the FETCh? query.
Executing this sequence of instructions is equivalent to READ?. The
INITiate[:IMMediate] command starts the acquisition. FETCh? determines the
requested signal characteristic and returns the result. This concept allows you to
perform several different FETCh? queries on a single set of acquisition data.
Example:
MEASure:AC? Configures the instrument to measure the RMS value
of the AC component of the signal at input channel 1,
starts the acquisition, and returns the desired result.
FETCh:FREQuency? Determines and returns the frequency of the signal
that is acquired by the preceding MEASure? query.
FETCh:RISE:TIME? Uses default parameters to determine and return the
rise time of the first pulse.
As distinct from the READ? query, defaulting the measure function part of the
FETCh? query, causes the CombiScope instrument to return the characteristic
that was requested with the last executed FETCh?, READ? or MEASure? query.
For this reason, the measure function should always be explicitly specified in the
header of the FETCh? query.