AS-Interface

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The AS-Interface (abbreviated ASi for English Actuator-Sensor-Interface ; German Aktor-Sensor-Interface ) is a standard for fieldbus communication that was developed for connecting actuators and sensors . The aim is to replace the previous parallel cabling. The AS-Interface is mainly used on the sensor / actuator level. The AS-Interface has been an international standard according to IEC 62026-2 since 1999.

history

In 1990 the companies Balluff , Baumer , Elesta , Festo , ifm electronic , Leuze electronic , Pepperl + Fuchs , Sick , Siemens , Eaton Corporation , Turck and Visolux initiated a system for networking sensors and actuators. The idea for the AS-Interface system was born. In a development partnership of 11 of these companies under the direction of Andreas Schiff (ifm) - supported by the TH Leipzig , Professorship Werner Kriesel and the Research Center for Computer Science (FZI) at the University of Karlsruhe , Professorship Klaus Bender - the implementation of the simple and cost-effective system solution began . Just one year later, the "Association for the Promotion of Bus-Capable Interfaces for Binary Sensors and Actuators eV" was founded (first chairman: Heinz Walker ; management: Otto W. Madelung ), which today represents the interests of member companies worldwide as the AS-International Association Maintains agencies in 13 industrialized countries (managing director: Rolf Becker ).

In 2018, a new technology step was presented at the international trade fair SPS IPC Drives in Nuremberg . This technology, known as ASi-5, was developed by well-known manufacturers in the automation industry in cooperation with the chip industry and with the University of Stuttgart (Professorship: Joachim Speidel ) and the University of Rostock (Professorship: Helmut Beikirch ) as well as with the HTWK Leipzig (Professorship : Tilo Heimbold ).

commitment

The AS-Interface (from the English Actuator Sensor Interface ) has been developed as an alternative to the conventional parallel cabling of sensors and actuators and offers the following advantages:

  • flexibility
  • economics
  • simplicity
  • Reduction of installation errors
  • High distribution
  • Best networking opportunities
  • compatibility

The main areas of application of the system are factory automation, process technology and building technology.

technology

The AS-Interface is a single master system , i.e. a master exchanges input and output data with all configured devices. An unshielded two-core yellow flat cable is used as the transmission medium. The cable is used for signal transmission and at the same time for power supply (24 volts). The communication electronics and subscribers with low power requirements, for example light barriers, can be supplied directly via this. Consumers with a higher energy requirement, such as valve terminals, can use a separate, usually black flat cable for the energy supply (24 volts). The sensors or actuators are often connected using the so-called piercing technology. Here, the insulation of the flat cable, which is profiled to be protected against polarity reversal, is pierced by means of two piercing spikes during assembly, without this having to be prepared beforehand. This means that slaves can be installed or relocated at any time without major assembly work. Sensors and actuators that do not have an AS-Interface connection can be connected to the system via modules. The AS-Interface flat cable must be used for modules with penetration technology. The topology of the AS-Interface networks is arbitrary. Line, star, tree or ring structures can be set up.

ASi-3 communication and transmission technology

A telegram consists of 4-bit user data. The master communicates with the participants using a serial transmission protocol. Each participant is assigned an address by an addressing device or via the master. A maximum of 62 participants can be connected. Each participant can have inputs or outputs for actuators or sensors, up to 496 inputs and 496 outputs are possible in one system. The serial communication is modulated onto the power supply. The Manchester coding is used. The cycle is 5 milliseconds for 31 participants. Two cycles are necessary to address 62 participants. The topology of the AS-Interface is arbitrary, but without a repeater or extender, the cable length must not exceed 100 meters. Using a special terminating resistor (a combination of resistive and capacitive load), however, it is possible to increase the maximum cable length up to 300 meters. Diagnostic devices or masters with built-in diagnostic functions facilitate troubleshooting in networks. Failed slaves can simply be exchanged, the master automatically re-addresses them. Safety at Work describes the concept of functional safety that is used in ASi-3 technology. This means that safety-related components such as emergency stop actuators, door locks or light grids are used in the AS-Interface network.

ASi-5 communication and transmission technology

16 bits are available for cyclical transmission with ASi-5. A cyclical transmission of up to 32 bytes per participant is possible. An acyclic parameter channel with up to 256 bytes is also available to each device. ASi-5 thus provides a quantity structure of up to 1536 binary inputs and 1536 binary outputs per Ethernet address. The system enables a cycle time of 1.2 milliseconds for up to 24 participants. This fast cycle time enables new fields of application that were previously reserved for expensive network systems. 96 participants can be addressed in an ASi-5 network. These 96 devices then have a cycle time of 5 milliseconds. Communication diagnostics describes the information on message transmission between the connected participants and the master. The system continuously monitors the transmission quality of the messages from the connected devices. This single channel diagnosis is available in the system. Disturbed transmission channels are automatically tracked. A device diagnosis provides information on the connected device. The available diagnostic data is determined by the device manufacturer. Diagnostic data can be transmitted via the acyclic services with a data width of up to 232 bytes. The ASi-5 system is open to the use of parameter interfaces such as IO-Link . IO-Link devices up to 32 bytes can be integrated cyclically and collected efficiently over large distances.

16 safe bits are available for functional safety devices such as emergency stop devices, safety light grids, safety switches and the like. SIL-3 performance level e according to IEC 13849 is achieved for functional safety. With ASi-5, a transmission of 16 safe bits is available for the safety-relevant switching devices.

ASi-5 uses a new type of communication method. The new procedure of the ASi-5 technology also enables the use of ASi-3 components (full downward compatibility), together with components of the new ASi-5 technology, on a common cable, as has been the case since the introduction of the ASi-3 technology is used (unshielded two-core yellow flat cable). If ASi-3 devices are to be used together with ASi-5 components, an extended master ASi-3 / ASi-5 must be used in addition to the corresponding devices. Existing systems can easily be upgraded with new devices with additional functions. New systems can be built with the new ASi-5 devices and at the same time with proven ASi-3 components mixed on one cable.

Normalization

The AS-Interface is described in the international standard IEC 62026-2: 2015.

Other local standards are:

  • Europe: EN 62026-2: 2015
  • Japan: JIS C 82026-2 (2013)
  • China: GB / T 18858.2 (2002)
  • Korea: KS C IEC 62026-2 (2007)

The certification of AS-Interface products is carried out by the "AS-International Association eV" Tests and certifications ensure that devices from different manufacturers work together. The functional safety concepts for AS-Interface were positively assessed by the TÜV (Technical Monitoring Association) and the Institute for Occupational Safety and Health of the German Social Accident Insurance , and compliance with the relevant safety standards was confirmed.

literature

  • Werner Kriesel , O. Madelung (ed.): ASI - The actuator-sensor-interface for automation. Hanser Verlag, Munich / Vienna 1994, ISBN 3-446-17825-2 , 2nd edition 1999, ISBN 3-446-21064-4 .
  • Werner Kriesel, OW Madelung (Eds.): ASI - The Actuator-Sensor-Interface for Automation. Hanser Verlag, Munich / Vienna 1995, ISBN 3-446-18265-9 , 2nd edition 1999, ISBN 3-446-21065-2 .
  • Werner Kriesel, H. Rohr, A. Koch: History and future of measurement and automation technology. VDI-Verlag, Düsseldorf 1995, ISBN 3-18-150047-X .
  • Werner Kriesel, Tilo Heimbold , D. Telschow: Bus technologies for automation - networking, selection and application of communication systems. Hüthig Verlag, Heidelberg 1998, 2nd edition 2000, ISBN 3-7785-2778-9 .
  • R. Becker: Automation is easy - with AS-Interface. AS-International Association, Frankfurt am Main 2008.
  • Wolfgang Weller : Automation technology at a glance. Beuth Verlag, Berlin / Vienna / Zurich 2008, ISBN 978-3-410-16760-0 , and as an e-book.
  • W. Wahlster: (R) Evolution 4.0 - Interview. In: trends in automation. The Festo customer magazine. No. 2, 2012, pp. 9-11.
  • Wolfgang Weller: Automation technology through the ages - development history of a fascinating subject. Verlag epubli, Berlin 2013, ISBN 978-3-8442-5487-7 , and www.edoc.hu-berlin.de, January 13, 2013.

Web links