Making Measurements; Controlling Measurement Samples - Agilent Technologies 66311A User Manual

Making Measurements

The dc source has the ability to make several types of voltage or current measurements. These
measurement capabilities are particularly useful for loads that draw current in pulses.
NOTE:
Because there is only one measurement buffer, you cannot measure output voltage and
current simultaneously.
All measurements are performed by digitizing the instantaneous output voltage or current for a defined
number of samples and sample interval, storing the results in a buffer, and then calculating the measured
result. Many parameters of the measurement are programmable. These include the number of samples,
the time interval between samples, and the method of triggering. Note that there is a tradeoff between
these parameters and the speed, accuracy, and stability of the measurement in the presence of noise.
There are two ways to make measurements:
♦ Use the MEASure commands to immediately start acquiring new voltage or current data, and return
measurement calculations from this data as soon as the buffer is full. This is the easiest way to make
measurements, since it requires no explicit trigger programming.
♦ Use an acquisition trigger to acquire the data as discussed under "Triggering Measurements". Then
use the FETCh commands to return calculations from the data that was retrieved by the acquisition
trigger. This method gives you the flexibility to synchronize the data acquisition with a transition in
the output voltage or current. FETCh commands do not trigger the acquisition of new measurement
data, but they can be used to return many different calculations from the data that was retrieved by
the acquisition trigger. Note that if you take a voltage measurement, you can fetch only voltage data.
NOTE: For each MEASure form of the query, there is a corresponding FETCh query. FETCh
queries perform the same calculation as MEASure queries, but do not cause new data to
be acquired.

Controlling Measurement Samples

You can vary both the number of data points in a measurement sample, as well as the time between
samples. This is illustrated in Figure 7-2.
Figure 7-2. Commands that Control Measurement Time
SENS:SWE:TINT <time>
SENS:SWE:POIN <# of points>
Programming the DC Source - 7
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