Programmable logic controllers (PLCs) are the core element of industrial plants in todays deployments. They read sensor values, execute control algorithms, and write output values. Furthermore, industrial plants have lifetimes of one or more decades. Thus, in a realistic Industry 4.0 scenario, these devices have to be integrated in novel systems. In order to apply advanced concepts and technologies, such as computation offloading, which requires data exchange between PLCs and edge cloud, we investigate open communication interfaces of two typical PLCs of Siemens S7 series. Hence, each of the interfaces is analyzed based on plug & play capability, if metadata is provided, protocol efficiency, and performance. For the latter, the smallest possible update time for each of the interfaces will be measured.

翻译：可编程逻辑控制器(PLC)是当今部署中工业工厂的核心要素。 它们读取传感器值, 执行控制算法, 并写出输出值。 此外, 工业工厂的寿命为1年或10年以上。 因此, 在现实的产业4. 0 假设中, 这些装置必须融入新的系统。 为了应用先进的概念和技术, 比如计算卸载, 这需要在PLCs和边缘云之间进行数据交换, 我们调查两个典型的Siemens S7系列PLC的开放通信界面。 因此, 每个界面都根据插接和播放能力( 如果提供元数据的话) 、 协议效率和性能来分析。 对于后者, 将测量每个界面的最小更新时间 。