MEASurement Commands 2
Keysight N8262A Programming Guide 145
FETCh[1]|2|3|4 Queries
The FETCh? queries set the specified window’s measurement function. This can be
set to either single channel, difference or ratio measurements, with relative mode
either off or on. They then recalculate the measurement and place the result on
the bus. The format of the result is set by FORM[:READ][:DATA]. Refer to
Chapter 6, “FORMat Subsystem,” on page 275 for further information.
The query returns a measurement result when it is valid. The measurement result
is invalid under the following conditions:
–When *RST is executed.
– Whenever a measurement is initiated.
–When any SENSe parameter, such as frequency, is changed.
If data is invalid, the FETCh? query is not completed until all data becomes valid.
The exceptions to this are, if the power meter is in the idle state and the data is
invalid, or the power meter has been reconfigured as defined above and no new
measurement has been initiated. In such cases, the FETCh? routine generates the
error –230, “Data corrupt or stale” and no result is returned. A common cause for
this error is receiving a FETCh? after a *RST. If the expected value and resolution
parameters are not the same as those that were used to collect the data, error
–221, “Settings conflict” occurs.
When TRIG:SOUR is INT1, INT2 or EXT and a new acquisition has been
initiated (using the INIT command for example), FETCH? waits until the trigger
takes place before executing. If triger conditions are not satisfied - when the
trigger level differs greatly from the signal level for example - this can give the
impression that the power meter has hung.
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