CMU Measurement Control
1100.4903.12 5.37 E-8
period. This implies that a single measurement result can be returned only once
by a SAMPle query; if called up repeatedly, SAMPle will return the result of sub-
sequent evaluation periods.
Due to this behavior, the SAMPle query is suitable for monitoring the progress of
continuous measurements in time. Multiple identical results, which might be
returned by repeated FETCh commands, are avoided.
A SAMPle query returns the results after interacting with the measurement (syn-
chronized query). This means that only valid results are returned, inconsisten-
cies are avoided.
Measurement states According to the definition given above the effect of the SAMPle query depends
on the measurement status and the history of the measurement:
Status Valid Results? Effect of SAMPle...?
STOP | RDY
| STEP
Yes Returns the current results. In this case, the SAMPle command
is equivalent to the FETCh command.
OFF No Generates an SCPI error –230, Data corrupt or stale. This is
why SAMPle should not be used while the measurement is in
the OFF state.
RUN Yes | No Waits until the end of the current evaluation period, returns the
results, and resumes the measurement (unless the current
evaluation period is the last to be measured).
STOP No Generates an SCPI error –230, Data corrupt or stale.
This scenario occurs, e.g. if the measurement is stopped ex-
plicitly before the first evaluation period has been terminated.
READ command
READ<type>:<meas_obj>[:RESult]<spec>?
Starts a new measurement, terminates the measurement and returns the results
after one single shot. The READ...? query is equivalent to:
ABORt...;
INITiate...;
FETCh...?
The READ command preserves all configurations (such as event reporting, stop
condition, statistics count...). READ initiates a measurement which is terminated
after one single shot (⇒ measurement state STOP, status RDY; if an error oc-
curred, the status is ERR). However, it does not affect the repetition mode set-
ting itself.
In case of no error (status RDY), the measurement can be continued by means
of the CONTinue command. It will be performed with the repetition mode set
before READ was executed.
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