AS-Interface/Bus Technology

Totally Integrated Automation Saves Time

By combining Profibus and AS-Interface, installing the entire electrical system carries only a fraction of the normal costs.

Consistent data management and integration automatically increase machine and system transparency. Just ask the set-up technicians at the SKF plant in Lüchow, who recently modernized their roller bearing production lines and now send control and safety signals via the same AS-Interface bus — even up to the higher-level master computer.

Totally Integrated Automation represents an important step in the right direction for the roller bearing manufacturer. Two 50-meter long internal ring production lines for manufacturing tapered roller bearings were retrofitted there with the latest technology. The best part of this update is the fact that Profibus DP and AS-Interface complement each other perfectly. Moreover, both standard signals and safety data are closely related and therefore simplify the system setup.

The actual solution is as follows: The electric drives in the system are attached to Profibus DP, whereas the sensors, valves and control elements communicate via the AS-Interface. While the Siemens safety monitor monitors the entire system emergency stop operating stations, which are located on an AS-Interface line, five of the ET-200S stations connected to Profibus provide the connection of the high feature motor starters for the 38 electric drives with the SIMATIC S7 CPU as the master.

The yellow and black AS-Interface cable as well as the purple Profibus cable run through the system from the face grinding machine to the tapered roller bearing internal ring laser signature. A SIMATIC S7-300 CPU controls all operations on the production line. It is located in the main control cabinet.

An ET 200S station with high feature motor starter, a safety monitor to safely shut down the system and the AS-Interface power supplies for the four AS-Interface lines in the system are also included. Two additional control cabinets provide space for the sub-distribution and the remaining high feature motor starters within the four ET 200S stations.

On the one hand, the fact that both Profibus and AS-Interface form a closed data stream is a major advantage for the production plant. On the other hand, standard and safety-related data can be transmitted via one common bus line. The Siemens program offers a wide spectrum of safety components for "ASIsafe". With the help of the SIMATIC manager and the completely programmed diagnostic blocks for ASIsafe, the entire plant can be monitored centrally during system startup. Generally valid: With SIMATIC Step7, machine operators are able to operate, monitor and archive data.

Thanks to a specially developed functional block for diagnostics, data can be forwarded from the AS-Interface safety monitor to the higher-level CPU, and the statuses of the safety slaves can be precisely evaluated. There is a functional block with similar functionality for Profibus error analysis, which sends and evaluates all diagnostic data from the individual distributed stations to the CPU, an effect SKF now enjoys thanks to AS-Interface and Profibus: "This saves an extremely large amount of time."

	AS-i/PROFIBUS - AS-Interface - Siemens \| 11/23/2008 11:38 AM

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