Identifying the Need for Multiple Output Functions on a Single Port
By default, eXpress creates a single output function on each output port of the design. There are times, however, when it is necessary to create more than one output function on a single port. There are a variety of situations in which this might be necessary, including:
The signal that emerges from a port is affected by multiple, separately testable capabilities of the part. In this situation, an output function should be created to represent each function of the part that can be separately diagnosed. For example, in a fuel system, two functions may be used to represent a device's ability to maintain the fuel's temperature and pressure.
The functionality of the part that emerges from a port can have alternative dependencies in different states. In this case, an output function should be created to represent each set of dependencies that the signal can have. For example, if a switch is used to choose between two data sources, then two output functions should be created to represent the two sets of dependencies.
An output port has functionality in common with another port on the same component (in other words, some portion of the component's internal functionality feeds both outputs). In this case, an extra function could be added to each port (using the same function name) to represent the functionality that is common to both ports (see also the topic "Functions Observable at Multiple Ports").
