This paper proposes a multi-resolution co-design modeling approach where hardware and software parts of systems are loosely represented and composable. This approach is shown for Network-on-Chips (NoC) where the network software directs communications among switches, links, and interfaces. The complexity of such systems can be better tamed by modeling frameworks for which multi-resolution model abstractions along system's hardware and software dimensions are separately specified. Such frameworks build on hierarchical, component-based modeling principles and methods. Hybrid model composition establishes relationships across models while multi-resolution models can be better specified by separately accounting for multiple levels of hardware and software abstractions. For Network-on-Chip, the abstraction levels are interface, capacity, flit, and hardware with resolutions defined in terms of object, temporal, process, and spatial aspects. The proposed modeling approach benefits from co-design and multi-resolution modeling in order to better manage rich dynamics of hardware and software parts of systems and their network-based interactions.