Measurement Computing LGR-5320 Series - Manual (Page 20)

LGR-5320 Series User's Guide Functional Details
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Below-level-with-latch trigger —With this trigger type, the channel becomes valid when the signal level is
below the threshold and remains valid until the acquisition is complete and re-armed—the opposite of above-
level-with-latch triggering). Latched triggers are often used in multichannel "AND" triggering—the acquisition
does not trigger until all trigger channels are valid. After a latched trigger becomes valid, it stays valid and waits
for the other triggers to become valid until the acquisition is triggered and completed.
If the trigger is not latched, the channel may not stay valid. A LGR-5320 Series device does not trigger the
acquisition until the channel becomes valid again, and all channels simultaneously reach their thresholds.
Latched triggering is used to trigger an acquisition after an event has occurred, while non-latched triggering is
used only during the simultaneous occurrence of desired signal levels. It is possible to combine different trigger
types in a single multichannel trigger.
For example, by configuring channel 3 for below-level triggering, and channel 2 for above-level-with-latch
triggering, the device could trigger the acquisition when channel 3 is below 0.9 V after channel 2 has gone
above –1.3 V.
Figure 15. Below level initialization, latched duration
Rising-edge trigger —This trigger becomes valid after the signal level has been below the hysteresis range and
then goes above the threshold. This trigger becomes invalid when the signal level goes below the hysteresis
range. Unlike above-level triggering, the channel cannot become valid until the signal level first goes below the
hysteresis range. This prevents the false triggering that would occur if the signal were above the threshold at the
start of the acquisition.
Figure 16: Rising edge, instantaneous duration, edge initialization
Falling-edge trigger —This trigger is the reverse of the rising-edge trigger: the trigger becomes valid after the
signal level has been above the hysteresis range and then goes below the threshold. This trigger becomes invalid
whenever the signal level goes above the hysteresis range. This prevents the false triggering that would occur
with below-level triggering if the signal was below the threshold at the start of the acquisition.
Figure 17: Falling slope, instantaneous duration, edge initialization
Trigger
Level
Threshold
Hysteresis
Trigger
No
Trigger
Hysteresis
No
Trigger
No
Trigger
Hysteresis
Trigger
Threshold
No Trigger
No Trigger
No Trigger