{"id":"sercos-iii","model_id":"SERCOS III","name":"SERCOS III","summary":"SERCOS III is an open, Ethernet-based real-time communication protocol for automation devices. It uses Fast Ethernet at 100 Mbps full duplex and summation-frame transmission, with configurable communication cycles from 31.25 μs to 65 ms and synchronization accuracy below 1 μs. It supports ring, line and star/tree topologies, direct cross communication between slaves, and safety functions up to SIL3 with CIP Safety according to IEC 61508.","study_notes":["Communication cycle time is configurable between 31.25 μs and 65 ms.","Synchronization accuracy is less than 1 μs.","Process data is consolidated into one summation-frame telegram rather than transmitted in individual telegrams.","Hot plugging does not affect real-time or synchronization characteristics.","TCP/IP and other Ethernet-based protocols can share the same cable with real-time data.","Sercos slaves can communicate directly with one another through cross communication.","Supported topologies include ring, line, and star/tree structures.","Ring redundancy is supported.","Devices and their positions in the topology are recognized automatically.","Drives can be parameterized over Sercos without a separate configuration device.","Sercos uses IEEE 802.3 Ethernet physics and copper or fiberglass cables."],"safety_notes":["Safety functions up to SIL3 can be implemented with CIP Safety on Sercos according to IEC 61508.","Safety-relevant and non-safety-relevant data are transferred over the same cable.","CIP Safety routing allows devices to communicate safely outside network boundaries.","In a ring configuration, cable breaks are recognized within 25 μs and data is lost for at most one cycle."],"sources":[{"url":"https://www.sercos.org/technology/","title":"Technology","accessed":"2026-10-25"},{"url":"https://www.sercos.org/","title":"Sercos Automation Bus","accessed":"2026-10-25"}],"verification":{"status":"source_checked","checked_at":"2026-10-25","values":4,"method":"llm_source_check"},"updated_at":"2026-10-25","type":"protocol","spec":{"transports":["ethernet_l2"],"architecture":"master_slave","encoding":"binary","default_ports":[],"data_types":[],"standard_body":"IEC","standard_ref":"IEC 61784, IEC 61158, IEC 61800-7","related":["iec-61508"]},"url":"https://machineschema.com/protocol/sercos-iii","license":"https://creativecommons.org/licenses/by/4.0/"}