ABSTRACT
SERCOS III is the third generation of an open and IEC compliant universal bus for Ethernet-based real-time communication standard. It is defined in IEC 61158, 61784, and 61800-7. It combines “on the fly” packet processing for delivering real-time Ethernet and standard transmission control protocol/Internet protocol (TCP/IP) communication to deliver low latency industrial Ethernet.
It uses summation frame method and operates without hubs and switches thereby reducing latency. Each station in the network has its own ASIC or FPGA. It processes data twice per cycle. Thus, devices communicate with each other without going through the master.
It is a multi-protocol capable one which makes it possible to transmit various communication protocols simultaneously by using a common and uniform network architecture. As an example, SERCOS III devices can coexist with Ethernet I/P and TCP/IP devices without real-time capability or functionality of individual protocols being compromised. A fieldbus system can be connected to a SERCOS network via a gateway.
It is capable of linking 511 devices with a jitter of ±10 ns. It can operate in both slave-to-slave and controller-to-controller modes.
Devices in a SERCOS III network need to comply with two separate addressing schemes: Ethernet’s media access controller (MAC) addressing and SERCOS III addressing.
