Yes, there are NO applications for WSN. The sensors "sense" the agent, and upon sensing application packets are generated automatically by NetSim. This happens in n_NetSim_Zigbee_SensorEvent( ) in sensor.c. Users can modify this to set their own packet size/arrival times.
Application models are available in our IOT (Internet of things) library from NetSim release v9 onwards
Application models are available in our WSN library from NetSim release v11 onwards