We present a Network on Chip (NoC) model with basic support for execution in constrained real-time. Actions for the processing element, switch, network interface, and channel components of NoC are specified in RT-DEVS, an extension of the DEVS formalism for real-time modeling. A desirable simulator must execute the actions defined in each NoC component within finite time periods. Execution of components' actions is supported by introducing a new capability to the DEVS-Suite simulator such that actions can be executed in real-time. The extended simulator can be used to develop, simulate, and evaluate the class of NoC designs that the underlying computing platform can support. NoC simulation can be used to obtain measurements such as system throughput and latency metrics under different communication patterns. This work offers a basis for future research where a NoC simulation can be embedded in a physical environment and thus enable NoC application designs and experimentations.