Measurement Computing LGR-5320 Series - Manual (Page 19)

LGR-5320 Series User's Guide Functional Details
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The first step in both multichannel and analog triggering is to examine the input signals. To determine trigger
validity, the FPGA can examine each input signal in one of eight ways. Refer to the following table.
LGR-5325, LGR-5327, LGR-5329 trigger signal attributes
Trigger type Slope Duration Initialization
Above-level N/A Instantaneous Level
Below-level N/A Instantaneous Level
Above-level-with-latch N/A Latched Level
Below-level-with-latch N/A Latched Level
Rising-edge Rising Instantaneous Edge
Falling-edge Falling Instantaneous Edge
Rising-edge-with-latch Rising Latched Edge
Falling-edge-with-latch Falling Latched Edge
The input signals are compared a specified signal level.
Above-level trigger —This trigger is valid whenever the signal goes above the specified level, and stays valid
until the signal goes below the level.
In Figure 12, the channel trigger is valid during the two shaded intervals.
With the LGR-5327 and LGR-5329, whether or not this condition triggers an acquisition depends on the type of
multichannel triggering (AND or OR) and on the state of other trigger channels.
 With OR multichannel triggering, the LGR-5327 and LGR-5329 triggers a scan when the signal first rises
above the threshold. If the device is ready and the condition is met, the scan is triggered.
 With AND multichannel triggering, the LGR-5327 and LGR-5329 does not trigger a scan until every
specified trigger channel is valid. If all other trigger channels are valid, the device triggers an acquisition
when the signal reaches the shaded region. If some channels are not valid, however, this channel has no
effect.
Figure 12. Above level initialization, instantaneous duration
Below-level trigger —This trigger is valid whenever the signal level is below the level and stays valid until the
signal goes above the level—the opposite of above-level triggering.
With the LGR-5327 and LGR-5329, as with all multichannel trigger types, the acquisition's actual trigger
depends on the combination of this trigger with the other channels' trigger states.
Figure 13. . Below level initialization, instantaneous duration
Above-level-with-latch trigger— With this trigger type, the channel becomes valid when the signal level is
above the threshold, and remains valid until the acquisition is complete and re-armed.
Figure 14. Above level initialization, latched duration
Level
Trigger Trigger
Trigger Trigger
Level
Trigger Trigger
Trigger Trigger
Trigger
Level