Active function propagation is utilized when one or more signals enter a part and a new signal leaves the part. For active functions (output functions that utilize active propagation), a single net function is created for each active output function, rather than for each of the received input signals. Since, with active propagation, signal flow is simplified, the original input signals are no longer visible to the Analyst (although, of course, the model still keeps track of the dependency).
The following diagram depicts three cases in which functions are propagated actively:
Active propagation is used when a function does not depend upon one and only one input (or bidirectional) port.
In the examples at left, the output of object X is active because the output function depends upon two inputs.
The outputs of objects Y and Z are active because the output functions depends upon no inputs (the control input to object Z does not count as an input when determining whether a function is active or passive). (Example a Battery has a charge that is not dependent on an input)
In each case, a single signal (or net function) is generated, named after the output function that produced it. Here a control port has been used to force the output into the Active mode.
When to Use Active Function Propagation
Active function propagation is most desirable when modeling specific dependencies on an object. When output functions require complex combinations of inputs, there is no purpose in trying to have the input functions passed through the part.
