A Novel Lightweight CAN-based Functional Safety Protocol for Low-Performance Embedded Systems

The Controller Area Network (CAN) is one of the important buses in industrial control systems. However, the complexity of its CANopen Safety functional safety protocol limits its application in low-performance devices. A novel lightweight CAN-based functional safety protocol based on Fail Safe Over EtherCAT (FSoE), referred to as Fail Safe Over CAN (FSoCAN), is proposed. To address the problem of FSoE incompatibility with the CAN bus, the FSoCAN communication model uses the CAN-TP protocol to extend the data frame length, and the calculating residual error rate method of FSoCAN is derived. To overcome the lack of a broadcasting mechanism in FSoE, a broadcast polling mechanism for FSoCAN is designed, and the method of calculating polling time is given. Theoretical calculations indicate that the residual error rate of FSoCAN can reach 7.03 × 10⁻¹³/h. Experimental validation demonstrates that FSoCAN effectively detects communication errors, such as faults, losses, and delays, with the experimental polling time deviating from theoretical values by only 0.01%. Compared to sequential polling, the broadcast polling method of FSoCAN reduces polling time by 27%. Both theoretical analyses and experimental results demonstrate that FSoCAN complies with the IEC 61784-3 functional safety fieldbus SIL3 standard and is suitable for low-performance industrial devices.