Safety Products with Integrated Bus Interface - EUCHNER GmbH + Co. KG - #4

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General 4 Subject to technical modifications; no responsibility is accepted for the accuracy of this information. Bus systems in safety systems Bus systems are also used for wiring safety products. The AS-Interface bus is recognized by accredited certification bodies. A consortium comprising various international companies was established to develop the safety-relevant part of the bus protocol. EUCHNER is actively involved in the development and production process in this organization. With the AS-Interface Safety at Work, a monitor is employed as an additional bus subscriber to monitor the protocol. This protocol is embedded in the AS-Interface protocol, and its purpose is to guarantee safety on the bus. With Safety at Work, the monitor also assumes the link functions realized using safety relays and terminals when parallel wiring is used in the control cabinet. The monitor is thus ultimately a programmable small safety control system. The bus technology thus considerably reduces the amount of wiring, not only in the field, but especially in the control cabinet as well. AS-Interface Safety at Work in safety systems AS-Interface is a low-level bus system that is used for the transfer of small data volumes. It is particularly suitable where digital signals are required in the field. However, analog signals can also be processed. Thanks to its simple structure, AS-Interface does not require any programming. For most bus subscribers, it is only necessary to set the address of the bus subscriber. No special knowledge of the bus is required. Any safety component can be connected to the bus. The monitor is designed so that these components can be connected irrespective of their manufacturer. Device compatibility is guaranteed at all times. When connecting an AS-Interface Safety at Work device, it is important not only to ensure compatibility with the bus, but also to facilitate compliance with the Machinery Directive. AS-Interface certification ensures that the bus subscribers also comply with the standards that apply to the bus. Certification by the stated bodies ensures that all safety components are in compliance with the Machinery Directive. The ASiMon software is used to implement the links in the monitor. All settings for the safety components are thus made in the monitor. Setup diagnostics can be selected and the logical component links can be implemented. The monitor thus represents the core of the entire safety system. It replaces both the wiring and the safety relays. The simple construction of a bus system practically eliminates the possibility of errors in the wiring. The bus and monitor diagnostic functions also facilitate rapid error detection. Consequently, setup can be performed directly after the planning phase and the preparation of the monitor configuration. The bus subscribers then simply have to be connected. The extremely effective bus diagnostic function is also useful during operation. Should an error occur during operation, all situations can be detected and displayed in the control system. Most EUCHNER safety switches have freely programmable LEDs that can be used for an effective diagnostic function. Any system standstills can thus be dealt with quickly. Operation of AS-Interface Safety at Work Replacing faulty components is very easy with AS-Interface Safety at Work. A bus subscriber that needs to be replaced only has to be substituted with a device with its address set to 0. The bus starts this device automatically when a button is pressed. This exchange thus progresses very rapidly and without the use of a programming device. It is even possible to replace the monitor with a new device without the use of a computer. In this case, a new device and a “push of a button” are all that is needed to get the system up and running again. Because of the many advantages of AS-Interface Safety at Work and the large selection of different of safety components, this system is also ideal as an autarchic safety system within an installation that uses a higher-level fieldbus. If the diagnostic function is required in this case, it can easily be incorporated in the higher-level bus by means of an integrated gateway. EUCHNER safety switches maximize all of the features that the bus has to offer. Switches with guard locking do more than just signal the position of the movable safety guards to the control system. They also distinguish and signal the position of the guard locking compared with the position of the door. Complete visualization of the safety guard is thus possible. EUCHNER provides full diagnostic functionality for the most common control systems. With EUCHNER switches, the guard locking is controlled using the bus. Because of the separate supply cable for the auxiliary power, the guard locking can also be activated as a safe channel. Many switches have LEDs integrated on the front; these LEDs can be controlled using the bus. On-site diagnosis can therefore be performed with the control system without the need for additional wiring. Minimization of the costs for hardware Instead of a separate monitor, EUCHNER also offers devices on which the monitor is directly integrated in the gateway. As a result the costs for hardware are reduced and the functionality increased at the same time. On the integrated gateway with monitor GMOx two complete AS-i buses can be connected; in the application these buses act like a single larger AS-i bus. In addition, the number of safe outputs increases to up to 16 per device used. On the GMOx devices, safe distributed outputs SOM can be used on the AS-i bus. These outputs have relay contacts for shut down, but can also read inputs at the same time. Control and also diagnostics in this case are via the GMOx. In addition the output SOM can be controlled by the machine control system during operation. This feature of course only works if the GMOx also provides an enable.