Upon the occurrence of an event at the REQ input of an instance of function blocks of this type, the value of the OUT variable will take on the value of the IN0 or IN1 input, depending on whether the value of the G input is FALSE or TRUE respectively, and an event will then occur at the CNF output.

The type of the IN0,IN1 and OUT variables is given by the suffix ( xxx ) of the FB type name.

An example of this family of FB types is shown above, where xxx = REAL .

These FB types are found in the src/select folder of the FBDK.