Understanding the real behavior of an application before implementation enables engineers to reduce development time and cost because it optimizes system resource utilization. This is true especially for a Wireless Sensor Network (WSN) whose evolution strongly depends on the number of nodes, on their configuration and on the amount of traffic. This implies the need for methodologies and tools which ensure that the final product satisfies the specifications while reducing analysis and development time. This paper presents reference WSN-oriented customization of an existing modeling framework in which the designer can build network components at every layer of the OSI protocol stack, consider details about physical layer and communication medium, easily exchange the WSN configuration, simulate it by analyzing several parameters and finally generate code for different target hw/sw platforms.