24/11/05 - Article - Safety at Work - AN UNFINISHED REVOLUTION
Now the last cable looms in modern plants can be cleared because the safety technology can be integrated in nearly all automation conceptsusing AS-Interface's Safety at Work. The technology venture Bihl + Wiedemann located in Mannheim takes care of providing the right connection to the respective system. |
| It is really not overstated to
describe the situation in the range of safety technology of modern plants as a
revolution. As every good revolution this one hold its own motto: "Together not
side by side." Up to now in automation, there had to be a double infrastructure: one for the not-safe signals and other for the safe signals. This combination leads to (especially cost) disadvantages. Now, the Safety at Work concept manages to integrate safety relevant communication into almost every existing automation system.
he meaning of this fact in practice can be demonstrated by means of an example that takes place at hundred of manufacturing facilities every day. Many budgets for installation were about to collapse previously if the Technical Supervisory Association (TÜV) required additional safety devices such as extra stops to certificate the plant. In such cases parts of the plant had to be rewired and more important newly documented. Today the new motto is: Just connect it to the yellow AS-i cable and ready! Bihl + Wiedemann: The right connection to almost all well-established automation systems It does not matter if it is Profibus or DeviceNet, if CC-Link or Ethernet: Safety at Work is able to offer its specific advantages just like AS-Interface itself for nearly all existing PLCs.
The technology enterprise Bihl+Wiedemann greatly contributes to AS-i's openness to well-established systems. This company from Mannheim, a new member of the AS-i Safety at Work consortium since 2005, is specialized in products speaking almost every language of the automation's world. The superordinated fieldbus treats the Masters, Gateways and Links as slaves, making their integration into a present network as easy as to link a standard slave. Extensive diagnostic functions as add-on The maintenance in respect of the plant's condition offers enormous potentials. Safety at Work users can be very glad to get all diagnostic functions of AS-Interface's innovation step 3.0 as an add-on. In contrast to conventional safety technology no additional connection is necessary, because the safety monitor, the heart of the concept, continuously communicates with the Master, being able to transfer the respective diagnostic information without any problem anytime. In addition the user gets the information which AS-Interface provides, because it is always listening to the telegram traffic on the bus. Long Line? No problem! In many cases the great functionality of AS-Interface leads to great network's extensions, but the limit 100 m from the "stone-age" of AS-Interface is now obsolete due to simple accessories.
Bihl+Wiedemann offers a big range in the field of circuit extension, too. Bihl+Wiedemann helps the user to handle the long-range-route with AS-Interface providing Repeaters, Bus Terminations or Tuners, depending on the individual requirements. The easiest and most flexible solution are the so-called IP20 Repeaters. Mounted directly into the switchboard in combination with an additional power-supply they allow to extend the network in 100 m steps. Furthermore the Repeaters can be used to isolate parts of a network from each other or to feed several segments of a network by separate power if necessary. The most cost-efficient solution to extend the circuit up to 200 m is to integrate the passive Bus Termination, provided that the compensation of the network's impedance is successful. If this is not the case, no problem: the AS-Interface Tuner, an active Bus Termination, for networks with length up to 300 m is at your disposal. It adjusts itself automatically to the situation found in the particular network during the teach-in-phase. As a matter of fact the components can be combined with each other. Using up to two repeaters in series, one can achieve lengths of up to 600 m (with passive bus termination) or 900 m (with tuners). A decisive advantage of tuning AS-Interface networks: there is no decrease in data security when using the AS-Interface Tuner. So it is allowed to involve the Tuner into AS-Interface Safety at Work networks or in plant's automation where the demanding requirements on the network's availability are high. |
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Article as PDF file |
The article appeared in AS-i Magazin, issue 2/2005
