User`s manual

66 Application Hints
PCIS-DASK
Digital Output Programming Hints
4.4 Digital Output Programming Hints
The PCIS-DASK provides three types of digital output operation:
non-buffered single-point digital output operation, buffered contin-
uous digital output operation, and pattern generation.
The non-buffered single-point DO uses software polling method to
write data to the device. The programming scheme for this kind of
DO operation is described in section .
The buffered continuous DO uses DMA transfer method to trans-
fer data from user's buffer to device. The maximum number of
count in one transfer depends on the size of initially allocated
memory for digital output in the driver. The driver allocates the
memory during system boot (in Windows
®
NT) or Windows startup
(in Windows
®
98). It is recommended that applications use
DO_InitialMemoryAllocated function to get the size of initially allo-
cated memory before performing continuous DO operation.
The buffered continuous digital output includes synchronous con-
tinuous DO and asynchronous continuous DO. These are
described in section and section . For special consideration and
performance issues for the buffered continuous analog input, refer
to Chapter 5: Continuous Data Transfer.
The Pattern Generation DO outputs digital data pattern repeatedly
at a predetermined rate. The programming scheme for this kind of
DO operation is described in section .