Wire restrictions
While a block's output can be connected to multiple other blocks, a block's input can only have a single connection.
It is also legal to leave a block's input or output unconnected if that is not required (the
Average (Mean) block in the example that is given in
Processing order of wires does not have anything connected to its
Sample or
Reset inputs).
Wires cannot create cycles. This means, the output of a block cannot be connected to
the input of the same block, or to
the input of any block that is connected directly or indirectly to one of the source block's inputs.
For example, there are three blocks: Block1, Block2 and Block3. A model would contain a cycle in the following cases:
The output of Block1 is connected to the input of Block2, and the output of Block2 is connected to the input of Block1.
The output of Block1 is connected to the input of Block2, the output of Block2 is connected to the input of Block3, and the output of Block3 is connected back to the input of Block1.
There are many possible connections which may lead to cycles in the model. The model editor, however, prevents you from creating cycles.