User`s guide

PCIS-DASK Application Hints • 33
5.1 Analog Input Programming Hints
PCIS-DASK provides two kinds of analog input operation  nonbuffered
single-point analog input readings and buffered continuous analog input
operation.
The non-buffered single-point AI uses software polling method to read data
from the device. The programming scheme for this kind of AI operation is
described in section 5.1.1.
The buffered continuous analog input uses interrupt transfer or DMA
transfer method to transfer data from device to user’s buffer. The maximum
number of count in one transfer depends on the size of initially allocated
memory for analog input in the driver. The driver allocates the memory at
system boot time (in Window NT) or Windows startup time (in Window 98). We
recommend the applications use AI_InitialMemoryAllocated function to get the
size of initially allocated memory before performing continuous AI operation.
The buffered continuous analog input includes:
- synchronous continuous AI
- non-triggered non-double-buffered asynchronous continuous AI
- non-triggered double-buffered asynchronous continuous AI
- triggered non-double-buffered asynchronous continuous AI
- triggered double-buffered asynchronous continuous AI
They are described in section 5.1.2 to 5.1.6 section respectively. About the
special consideration and performance issues for the buffered continuous
analog input, please refer to the Continuous Data Transfer in PCIS-DASK
chapter for the details.