The Boolean Fan Input function block is useful to detect and trap one or more of the discrete inputs as it transitions to the Set state. When this condition is detected, a copy of the OUT_INT output is held in the block's FIRST_OUT output. This output can be used to determine which input(s) or initial conditions caused a machine to fail. The OUT_INT output always reflects the state of the inputs, whereas the FIRST_OUT output updates only when the IN_Dn parameters transition from all zero to one or more non-zero and ARM_TRAP is non-zero.