Real-time network communication using 8B10B coding for mechatronics control

Abstract

High-speed and high-precision actuator control is required for industrial manufacturing equipment. In such systems, the control operation cycle needs to be shortened to 100 μs or less. Recently, the quantity of sensors and actuators is increasing because new control methods have been developed. Therefore, the amount of information input/output to/from sensors and actuators is also increasing. Any electromagnetic noise occurring inside the equipment due to using high-voltage power or various actuators affects the system performance. The authors are thus developing a network communication system for high-speed and high-precision mechatronics control considering electromagnetic noise. The network communication adopts an original protocol operating in the 40-MHz band with 8B10B coding for SerDes logic implemented on an FPGA. In this paper, a method for the K-code usage of 8B10B coding to reduce packet transmission overhead is proposed, as well as a data transfer scheduling method that can reduce communication delay by setting a communication period for each data and distributing the amount of data transfer per communication cycle. Evaluation results show that the cycle-to-cycle jitter in sampling between the main controller and the control device was 260 ns. In addition, the data transfer scheduling reduced communication delay by 36% compared to the case without the scheduling.

Keywords

• fpga
• field network
• serial communication
• distributed system
• real-time network