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13-2 SCPI Signal-Oriented Measurement Commands Model 2520 User’s Manual
Command summary
The signal-oriented measurement commands are used to acquire readings. You can use
these high-level instructions to control the measurement process. These commands are
summarized in
Table 13-1 .
Acquiring readings
FETCh?
Description
This query command requests the latest post-processed readings stored
in the reading buffer. After sending this command and addressing the
Model 2520 to talk, the readings are sent to the computer. This com-
mand does not affect the instrument setup.
This command does not trigger source and measure operations; it sim-
ply requests the last available readings. Note that this command can
repeatedly return the same readings. Until there are new readings, this
command continues to return the old readings. For example, assume that
the Model 2520 performed 20 source and measure operations. The
:FETCh? command will request the readings for those 20 source and
measure operations. If :FETCh? is sent while performing source and
measure operations (ARM annunciator on), it will not be executed until
the Model 2520 goes back into idle.
NOTE
The :FETCh? command is automatically asserted when the :READ? or :MEA-
Sure? command is sent.
The readings that are acquired depend on which data elements are
selected (
Section 14 , “ FORMat subsystem ,” “ Data elements ” ). Measure
readings take priority over source readings, and data from channels not
sourced or measured are assigned the NAN (not a number) value of
+9.91e37.
Table 13-1
Signal-oriented measurement command summary
Command Description
:FETCh?
:READ?
:MEASure? Requests latest readings.
Performs an :INITiate and a :FETCh?.
If output is off, turns output on. Performs an :INITiate and
a :FETCh?.