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.

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_DISCRETE_DATAREC.edge and MXF_DISCRETE_SAMPREC.edge specify the mask.
For direct IO, the port mask is specified as parameter for the read or write functions.