As computation and communication resources get more and more economical and reliable, measurement and control systems are becoming more large-scale, distributed, and software-enabled. This presentation focuses on the run-time models for software running on the computational nodes in distributed measurement and control systems.
We start with an overview of run-time models, classifying them in terms of message acquisition styles, message semantics, triggering mechanisms, scheduling mechanisms, and notions of time. Then, we discuss four models that are built in Ptolemy II, two long-existing ones, synchronous dataflow (SDF) and finite-state machine (FSM), and two newly developed ones, real-time processes (RTP) and time-synced discrete event (TSDE).