Safety is becoming an increasingly important topic in machine and plant construction. This has become evident in legislation and tightened safety requirements in national and international standards designed to protect human beingswww.cechina.cn, material assets控制工程网版权所有, and the environment.
        The goal of functional safety is to minimize or even eliminate the risks that can occur during normal or impaired operation of machines or facilities. Here, safe position measuring systems are essential.
        The increased use of processors and programmable systems led to a revision of the EN 954-1 standard, which had been in effect for machine construction since 1997 and was harmonized under the European machine directive. The EN 954-1, with its deterministic approach, was no longer adequate for the new requirements—a fact taken into account in its successor standard, EN ISO 13849. This new standard includes the reliability of components and programmable codes similar to the IEC 61508www.cechina.cn, as well as the product standards derived from it, such as IEC 62061 for electrical drives.
        Particularly in mechanical and plant engineering, moving axes are a potential danger, inspiring increasing numbers of designers to integrate the mandatory safety functions directly in the drive. As a result, a technical trend has emerged toward purely digital transmission of position values from an encoder to the drive Control. This means that more complex electronic systems have become necessary in both the drive control and the encoders for precise position acquisition. The functions now available in machine and manufacturing systems and the concomitant stringent safety requirementswww.cechina.cn, as defined in the relevant new standards控制工程网版权所有, call for position encoders with entirely new solutions for safety-related applications.

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