Highly accurate synchronization of system time in distributed systems with IEEE 1588

IEEE 1588 is a standard to synchronize the clocks of distributed devices in a network. Current protocol versions are based on the specification IEEE 1588-2008, also called 1588 V2. Depending on the hardware and topology used, accuracy down to a two-digit nanosecond range can be achieved. With an increasing number of devices providing hardware support for IEEE 1588, also the number of applications grows…

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New methods for the analysis of the physical layer of CAN networks and possibilities for robustness improvement

By Tobias Frey and
Thomas Waggershauser

With CAN-based systems being used in manifold applications that require continuous operability, also under harsh environmental conditions and extended service-cycles, the verification of CAN operability is essential. Especially, the direct detection of failure sources enabling thorough maintenance before systems may fail…

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In CAN networks the underlying transport protocol sets structural limits to the system in standard applications. CAN currently manages a 1 Mbit/s transmission rate, given that the overall network cable length does not exceed 25 meters. If longer lines are necessary, the transmission rate must be recuded – the longer the distance, the higher the speed loss. However, with suitable topology components, high bandwidths can be realized even in large networks. Specific benefits of various solutions will be outlined in the article.

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Industrial Ethernet is the talk of the day and the list of its promises is impressive: high data rates, long cable distances, and cost-efficient standard cables and plugs make Ethernet technology seem the communication medium of the future for automation manufacturers and users. While the benefits cannot be denied, Industrial Ethernet systems are not necessarily the best communication solution for each and every application. CAN is still a very simple, flexible, and powerful network technology which, considering its low costs, is an unrivaled solution for many applications.

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Thanks to the availability of real-time extensions and low-cost components, Ethernet is increasingly used in automation and metrology. For many automation applications, exact time synchronization of controls, sensors and actuators within a network or even between several networks is vital. One possibility for this is offered by the “Precision Clock synchronization Protocol for Networked Mea-surement and Control Systems” or „Precision Time Protocol” (PTP) for short, which is defined by the IEEE standard 1588. However, the protocol only provides the basis: maximum precision for synchronization requires support from suitable hardware. The following text describes how IEEE 1588 PTP works and what hardware-based solutions are suitable for it…

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