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Chapter 5
PCI-1712/1712L User’s Manual
Advantech Co., Ltd.
www.advantech.com
Analog Input Acquisition Modes
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:
q 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.
q 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.
q 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:
w Set to Post-Trigger Acquisition Mode
w The A/D sample clock source and sampling rate
w The trigger source and edge type
w The acquired sample number N