Simulation of structured text language for PLC programming

Programmable Logic Controllers (PLC) have been used for long in Industry and are part of learning programs in academia. The utilization of these devices must be done with care due to their electrical connections and to the work with possible dangerous or sensitive machines. As such, learning to program and use those in a safe and effective way is recommended and desired both in industrial and academia contexts. We describe a software simulator, which simulates a PLC TSX3721 as well as its programming code, namely Structured Text (ST), and also a HMI panel. It can be used to simulate discrete-event systems, discrete-time systems and hybrid systems, at their several working stages. A description of the PLC simulation architectures and its development is provided, as well as illustrative examples.