This paper describes an educational system demonstrating the use of conventional devices and consumer-grade embedded systems for distributed industrial automation applications.
Modern industrial PLCs use remote I/O units to gather and deliver information for the monitoring and control of industrial processes. These distributed remote units are usually interconnected to the central PLC using an industrial communications network. Nowadays there is some convergence towards the use of Ethernet with supporting protocols such as Profinet, Ethercat, Ethernet/IP, Modbus/TCP, among others.
On the one hand, both central units, implemented through industrial PLCs, and I/O modules, have been mostly available from very well established manufacturers, mainly due to demanding regulations and high standard requirements in most fields of industrial automated processes.
On the other hand, a new generation of embedded systems with very high processing capabilities and at low cost, make it possible and very attractive to consider their use in substitution of the more conventional established-brand PLCs and I/O modules, especially when dealing with applications for less regulated environments. Some examples of successful deployments are those based on the Arduino, such as the Controllino PLC, the M-Duino and the Iono Arduino, as well as those based on the RaspberryPi computer such as the Iono Pi and the UniPi.
The developed educational system consists of a Central Control Unit that can be either a Siemens S7 1200 PLC, a ARM Cortex M3/4 Board with embedded communications peripherals, or a RaspberryPi very small form factor single-board computer, including communications hardware. For the Remote I/O Module a Vipa 053-1MT00-IM053 Interface Modbus/TCP Slave or a Arduino Uno Board with an Ethernet Shield can be selected. Any combination of central unit and extension module can be used while communications are implemented through the ModBus/TCP protocol at a speed of 100 Mbps.