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Automation Technologies 2/2014

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  • Automation
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Automation Technologies 2/2014

Components and software

Components and software back to current issue previous page 02 With shared devices, failsafe and standard controllers can jointly access the same device to integrate them into the Ethernet-based Profinet without any system discontinuity. Thanks to a minor adaptation of the F-CRC (cyclic redundancy check) and of the sequence counter in the PROFIsafe frame, communication errors caused by switches or WLAN clients can now also be detected. Experts from numerous renowned companies in the PROFIsafe workgroup of PI examined further error scenarios and mathematical calculations of errors and drew up solutions for them so that PROFIsafe today offers the highest possible status of safety-related communication. Among other things, PROFIsafe machines and plants up to PL e according to ISO 13849-1 or SIL3 according to EN 62061 can be implemented. High-flexibility features Yet the developers of PROFIsafe did not focus solely on safety-related communication; they also simplified the engineering and replacement of equipment. With the aid of the Tool Calling Interface (TCI), the configuration engineer simply has to call the specific configuration software of an F-device in order to process the individual F-parameters. This is possible directly from the engineering environment. The F-parameters are saved locally and additionally stored in the CPU by means of a specified i-Parameter server. In the event of a device being replaced, these specially saved parameters can be downloaded from the CPU to the new device without any further assistance from the engineering. A further option is the switching on and off of individual channels — without any repercussions on the other channels in the same failsafe I/O module. The corresponding amendment to PROFIsafe specifies this “channelgranular passivation” and the appropriate presentation of the quality of safety-related input and output signals. Completely new plant and machine designs are feasible through the transmission of safetyrelated data over wireless connections, which is only possible with PROFIsafe. For example, communication cables no longer have to be laid in the festoon cable systems of crane systems subject to high stress, for example, or in the vicinity of power rails in transport systems that are subject to high levels of interference. Safety-related communication over wireless LAN permits the integration of emergency-off pushbuttons and the associated acknowledgment mechanisms on wireless panels, which considerably simplifies the development of mobile operating concepts. What is more, PROFIsafe permits the connection of safety-related Intrinsic Safety (Ex-i) devices via a PN/PB link. Even if an application demands the separation of the F-controller and the standard controller, the savings of a shared network and the integration of safety functions into devices can be exploited with the aid of a shared device. Conclusion A growing number of device manufacturers and integrators, having taken the first step of using PRO- FIsafe, are recognizing the additional possibilities offered by the protocol. With the “safe speed” feature, for example, plant sections do not necessarily have to be safely shut down, but can carry on running under these conditions. In connection with PROFIdrive for the standardized control of drives and PROFIenergy for energy saving, PI offers a comprehensive package of standardized and globally accepted solutions. www.profibus.com AUTOMATION TECHNOLOGIES 2/2014

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