Abstract

Control systems for factories, buildings, grid infrastructure and transportation currently use industrial Ethernet protocols such as PROFINET®, CC-Link®, EtherCAT®, and many others to manage and control production lines, robots, and automation. The short cycle time of real-time Ethernet makes it possible to run control algorithms with a central control unit. IEEE Ethernet standardization has introduced several standard features under the umbrella of Time Sensitive Networking (TSN) to enable achieving the real-time required by these applications.

In practice, the existing versions of industrial Ethernet protocols are sufficient and still used. Industrial Ethernet protocols such as EtherCAT often utilize standard IEEE 802.1Q Ethernet at the controller and modified solutions at the devices. To improve the preciseness of timing of placement of a frame on the wire, some non-IEEE standard solutions like time triggered send (TTS) are being used at the devices.

This application note features the use of the standard TSN feature of Enhancements to Scheduled Traffic (EST) at the controller in comparison to standard Ethernet protocols. EST, also known as time-aware-shaper or Qbv, is one of the fundamental TSN features available in modern embedded processors. A comparison of achievable timing accuracy between a standard TSN based solution and a vendor specific TTS are presented in this application note.