Sequoia / Tahoe Series User Manual California Instruments
M447352-01 REV-A 251
Figure 7-4. HARMONICS Menu, Triggering
The following trigger sources are available in the HARMONICS menu:
Entry Description
Immediate This mode causes a trigger to occur as soon as the START field is
tapped. No trigger source needs to be specified for this trigger mode.
This mode is equivalent to the SCPI command, INIT:IMM:ACQ.
This trigger source is appropriate if no trigger condition is known or
desired. When using this trigger source, the acquisition is always
triggered.
Phase This mode causes the acquisition system to wait for the zero phase
angle of the output voltage. The phase angle of the current with
respect to the voltage is determined by the load, so triggering at a
specific current phase angle is not possible, since it is not controlled
by the power source. However, when capturing current waveform
data, the phase relationship to the voltage can be determined easily
by triggering at the 0° point on the voltage.
7.3.3 Trigger delay
The trigger DELAY field allows setting the amount of pre- or post-trigger data that should be used when
positioning the data acquisition window with respect to the trigger event.
Entry Description
POST-TRIGGER DELAY Positive trigger delay value means the acquisition window is delayed
by the amount of time specified. In this case, the actual trigger instant
itself is no longer present in the acquisition buffer. This condition is
shown in Figure 7-5, where a 20 ms trigger delay is used after
triggering on phase = 180°, with an output frequency of 50 Hz. The
trigger point is indicated by the dashed line; it occurs on the first 180°
point that occurs after the START field is tapped. Once the trigger
occurs, the acquisition holds off the specified 20 ms, after which the
data is captured. Using a positive trigger delay value always yields
post-trigger data. Positive trigger delay values may be set from 0.0 ms
to 1000.0 ms (1 second) in 0.1 ms increments. The value may be
entered directly with the touch-screen keypad or using the rotary
encoder.
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