An architectural approach for reconfigurable industrial I/O devices

This paper presents an architecture concept for reconfigurable industrial I/O devices. In order to avoid the use of special hardware modules as well as to offload the PLC from real-time preprocessing of sensor data, these tasks are shifted into the reconfigurable I/O device. Therefore, an FPGA based architecture template is proposed that supports loading of application-specific functions into the I/O device at runtime. The architecture template is partitioned into a static part and several reconfigurable slots. While the static part implements all fixed design elements, like the communication with the field bus and the in-system CPU, all application-specific functions are mapped onto the reconfigurable slots. In order to perform the reconfiguration of application-specific functions at runtime, the partial reconfiguration technology of modern FPGAs is used. The proposed concept is evaluated by mapping a case study with four reconfigurable slots onto a Xilinx Zynq-7000 SoC. The results show that new application-specific functions can be flexibly loaded into the I/O device. The total reconfiguration process of exemplary application-specific functions requires up to 3 ms and cause down-times below 0.5 ms. This especially enables new control applications that can even change the preprocessing within I/O devices during cyclic data communication.