24 |
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USB-3200
AI
AI-SENSE
+
Vcm
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Figure 3.8 grounded signal source NRSE input
3.5.
Signal acquisition mode
When the USB-3200 series data acquisition
device
performs analog input measurement, it
supports continuous acquisition mode or limited number acquisition mode. The sampling rates of
both modes are hardware-timed. The limited number acquisition mode is called OneShot mode.
Hardware timing
Hardware timing means that the sampling rate of AI acquisition is controlled by a hardware digital
signal (AI sampling clock), which can be generated internally or externally.
Please refer to the chapter of “Synchronization system” for detailed settings for using externally
provided sampling clocks.
Continuous acquisition mode
Continuous acquisition mode refers to continuous and uninterrupted collection of data at defined
sampling speed.
In continuous acquisition mode, after the AI acquisition is triggered, the acquisition
device
collects the signal at a fixed sampling speed, buffers data into FIFO, and continuously uploads the
data in the FIFO to the computer memory buffer. The user program only needs to continuously
process the data in memory to achieve continuous uninterrupted data acquisition.
If the user program does not process the data fast enough, the data will gradually fill the 2M points
of storage space in computer memory buffer. New data cannot be written correctly after the