SoftPLC-Based Control: A Comparison between Commercial and Open-Source EtherCAT Technologies

Nowadays, most control systems are based on programmable logic controllers (PLCs) and on commercial programs, but the use of conventional PCs is becoming an increasing by popularity and competitive alternative. After an introduction that underlines the positive and negative aspects of both solutions, EtherCAT, a hard real-time industrial Ethernet protocol that allows the use of both conventional PCs and open-source software, is analyzed. Two different EtherCAT master implementations are compared, which are based on a commercial and on a open-source software, respectively. In order to highlight differences and provide a short reference, a simple example was implemented in the two environments.