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Chapter 5
The PCI-1712/1712L can acquire data in single value, pacer, post-
trigger, delay-trigger, about-trigger and pre-trigger acquisition modes.
These analog input acquisition modes are described in more detail in
the followings:
Single Value Acquisition Mode
The single value acquisition mode is the simplest way to acquire data.
Once the software issues a trigger command, the A/D converter will
convert one data, and return it immediately. User can check the A/D
FIFO status (A/D_F/E on Read BASE+8) to make sure if the data is
ready to be received. For detailed information, please refer to Appendix
D.9 Interrupt and FIFO status.
Pacer Acquisition Mode
Use pacer acquisition mode to acquire data if you want to accurately
control the time interval between conversions of individual channels in
a scan. A/D conversion clock comes from A/D counter or external
AI_CLK on connector. A/D conversion starts when the first clock
signal comes in, and will not stop if the clock is still continuously
sending into it. Conversion data is put into the A/D FIFO. For high-
speed data acquisition, you have to use the DMA data transfer for
analog input to prevent data loss.
Post-Trigger Acquisition Mode
Post-trigger allows you to acquire data based on a trigger event. Post-
trigger acquisition starts when the PCI-1712/1712L detects the trigger
event and stops when the preset number of post-trigger samples has
been acquired or when you stop the operation. This trigger mode must
work with the DMA data transfer mode enabled.
Use post-trigger acquisition mode when you want to acquire data
when a post-trigger event occurs. Please specify the following
parameters when using software in post-trigger acquisition mode:
Set to Post-Trigger Acquisition Mode
The A/D sample clock source and sampling rate
The trigger source and edge type
The acquired sample number N
PCI-1712/1712L User's Manual
– 34 –
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