Designing of a General Purpose Soft Programmable Logic Controller (PLC) for the Internet of Things (IoT) Era

Programmable Logic Controllers (PLCs) have dominated in the automation and in the controlling processes in industrial environments in the past decade. However, with the emergence of Internet of Things (IoT), the controlling and the automation processes have escalated to complex levels. Data should be harvested from different locations to make one decision for different devices. Communication and networking over the Internet is an important feature of the new controlling process. Moreover, smart control requires the implementation of different heavy-computing machine learning in Clouds or in edge devices. These new issues require an upgrade of the ossified PLC design. In this paper, a new soft-PLC device has been designed. The new design tackles three main issues. First, designing a simple interface to read data from analog and serial sensors without any modifications of the PLC. Second, proposing an enhanced LADDER programmer (ELADDER) to allow networking between servers and PLCs without the complexity of learning other programming languages. Finally, enhancing the computational power of the PLC by introducing multi-threading to control different processes in a parallel method. The proposed soft-PLC has been designed utilizing a system on board for the computational process and a micro-controller for sensor interfacing. The proposed soft-PLC has been tested in a Lab with different controlling tasks, reporting and networking.