All discrete lines have edge detection capability. Active lines and edge polarity (rising or falling edges) are selectable line by line using a mask value. When a selected line changes in the selected direction, a corresponding bit is set in an edge detection field.

Sampling mode does not use the edge detection functionnality, it simply returns the current lines state in the FIFO at each sampling period.

IO access

Two types of access are defined for the software support of the discrete devices.

FIFO
In this mode, an application uses MX Foundation services to send and receive sequences of signals.
Direct
In this mode, an application controls / monitors directly the discrete port signals.

Port Masks

Both types of access use a port mask value to define on which line(s) the operation takes place.

For the FIFO services, the MXF_FLEXDIO_DATAREC.edge and MXF_FLEXDIO_SAMPREC.edge specify the mask.
For direct IO, the port mask is specified as parameter for the read or write functions.