In consultation with users and suppliers, SERCOS International (SI) is developing a specification for an encoder profile for the SERCOS III real-time Ethernet protocol. It is expected to be available in November 2009, along with a conformance test being developed in parallel to ensure interoperability of different devices.

In the first and second generation SERCOS interfaces, absolute and incremental encoders were connected to the servo drives or to the control system via a separate fieldbus, and not directly to the real-time bus. Because of the universal use of real-time Ethernet-based SERCOS III, there has been a demand to directly integrate encoders into a SERCOS III network. The new encoder profile ensures that the functions (absolute or relative) are made available via clearly defined vendor-independent interfaces. The profile defines the functions supported by a device and how these functions may be used by other devices, such as control systems or servo drives.

SI also will provide an open source software driver library for the SERCOS III real-time Ethernet communication system master implementation. The driver software will be available as source code, without any license fees or usage limitations.

SI is cooperating with the Open Source Automation Development Lab (OSADL) to disclose the SERCOS III master driver. The OSADL eG is an international cooperative that promotes and coordinates the usage of open-source software for machine and plant control systems.