User`s manual

Application Hints 63
PCIS-DASK
Digital Input Programming Hints
Multiple-buffered Asynchronous Continuous Digital Input
This section describes the function flow typical of multi-buffered
asynchronous digital input operation. While performing continuous
DI operation, the DI configuration function has to be called at the
beginning of the application. For asynchronous DI, the SyncMode
argument in continuous DI functions has to be set to
ASYNCH_OP.