Robotic systems often operate under real-time constraints,requiring timely responses to sensor inputs. Early consideration of suchrequirements during design is advantageous. The Robot Operating System(ROS) provides a mature framework for system setup and communication,with ROS2 offering real-time capabilities. However, determiningthe maximum reaction time within a ROS network is intricatedue to complex variable processing and scheduling, especially with periodicand event-triggered tasks. In this report, we propose a model ofROS-based structural designs with timed automata semantics, facilitatingreal-time behavior analysis. We extend this model to incorporatenon-deterministic execution time and probabilistic loads, employing statisticalmodel checking (SMC) for scalability and accuracy. We compareagainst previous work to confirm the validity of our approach.