I/O flags are objects that describe how signals enter or leave the design. Depending on how it is configured, an I/O flag may describe a single signal or a group of multiple signals. I/O flags differ from Connectors in that diagnostic calculations will exclude them from consideration as sources of failure.
When to Use I/O Flags
Nearly all designs require I/O flags (the only exception being when connectors are used instead). Although I/O flags may appear anywhere in the design, they are typically placed around the edge of the design. External signals entering the design, like power and ground, are modeled using an I/O flag with an output port (the signal enters at the I/O flag, then flows out of the flag's output port into the design).
I/O Flag Rollup Method
In the context I/O Interpretation Panel, the Rollup Method is used to specify how output functions will be created on the port that corresponds to a given I/O flag on an upper-level assembly. There are two different rollup methods that can be selected for a given I/O flag:
Single Output
By default, I/O flags represent a single signal either entering or leaving the design. On higher-level assemblies that link to that object, a single output function will be created on the port that corresponds to that I/O flag.
Multiple Output
When this rollup method is selected, multiple output functions may be created on upper-level ports that are linked to that I/O flag. One upper-level output function will be created for each net function that reaches the I/O flag at the lower level.
Working with I/O Flags
For more detail on working with I/O flags, choose from the following:
