ADLINK Technology NuDAQ PCI-9812/10, Руководство пользователя

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Operation Theorem
Middle-Trigger Acquisition
Use middle-trigger acquisitions in application where you want to
collect data before and after a specified trigger event. Acquiring
data before a trigger event occurs for Middle trigger might not get
the specified count of data, just like the pre-trigger mode.
DMA start External trigger Event DMA Stop
The desired number of samples after trigger event is pre-loaded in
post trigger counter register and will count down on the rising edge
of ADC sampling clock after the trigger condition is met. When the
count reaches 0, the counter stops. The trigger can either be an
external analog trigger or digital trigger.
Delay Trigger Acquisition
Use delay trigger acquisition in application that you want to delay
the data collection after the occurrence of a specified trigger event.
The delay time is controlled by the value which is pre-loaded in the
post trigger counter register. Then the counter counts down on the
rising edge of ADC sampling clock after the trigger condition was
met.
When the count reaches 0, the counter stops and PCI-9812/10
starts to acquire data.
External trigger Event Acquisition start DMA stop
post trigger counter
count from N down to 0
Acquire n A/D data
Time
Acquire n A/D data
after trigger event Acquire m A/D data
before trigger event
Time