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AS-Interface: The fieldbus standard

AS-Interface (ASi) is used for communication within automation technology and is a supplement to the conventional standard fieldbus systems. With ASi, various field devices, such as sensors and actuators, can be integrated into a controller at the lowest automation level. But what exactly is AS-Interface? Which technologies are used here and what advantages do you as a company gain by using ASi?

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L’interface AS vous offre les avantages suivants :

  • Simplicité : avec elle, vous profitez d’une intégration aisée et d’une installation rapide
  • Efficacité : le protocole intelligent offre une sécurité accrue
  • Flexibilité : l’intégration flexible est possible de manière directe ou décentralisée au choix
  • Rentabilité : réalisez des économies en réduisant le nombre de câbles

Fundamentals of AS-Interface

Use of AS-Interface at field level

AS-Interface (Actuator-Sensor-Interface) is a global standardised fieldbus system for connecting sensors and actuators to a higher-level controller via a common data transmission medium.

AS-Interface is used at field level and generally serves to transfer process data to a higher control level. For example, field devices can be integrated into existing networks either directly via the so-called ASi master or via a gateway. Specific information and process data are transmitted between the field devices and the controller using a 2-wire yellow AS-Interface profile cable. This special AS-Interface cable is used for both transmitting data and supplying power to the field devices.

Simple configuration of AS-Interface

Master-slave communication model

At field device level, AS-Interface is governed by the master-slave principle. In this case, communication between the ASi master and its slaves (field devices) occurs as a cyclic request. The ASi master manages data traffic, thereby connecting the participants to the higher-level controller. The master thus monitors and controls the entire data exchange within the network. It sends information to the slaves, which then evaluate it (filter out the information intended for them) and send back a response to the master. Slaves can be simple, individual field devices or compact field modules.

Integration options of AS-Interface in automation systems

As standard, AS-Interface is implemented as a sub-fieldbus system in established, high-performance fieldbus systems and Industrial Ethernet for communication purposes. This extends down to the lowest field level.

PLC
A PLC, or programmable logic controller, is a special computer that is primarily used by the industry for control and regulation purposes.
Gateway
A gateway is used to connect various types of networks and communication services.
Control head 8691
Type 8691 - Control head for decentralised automation of process valves ELEMENT. Discover more.
Control head 8681
Type 8681 - Control head for decentralised automation of hygienic process valves. Discover more.

The network topology

AS-Interface can be used to flexibly select the network topology. As a result, a linear structure is just as suitable as a star or tree structure. ASi protocol thus allows for modular expansion of an industrial communication network, which in turn enables individual adaptation to the topology of existing systems. At the same time, cabling within the network can also be reduced. This level of flexibility leads to a significant reduction of cabling effort within the network.

The AS-Interface flat cable

Data transmission and power supply through a single cable

The yellow AS-Interface flat cable is characterised by the fact that data is transmitted and power supplied to the field devices via the same 2-wire profile cable.

For the additional supply of certain 24V DC field devices or modules, a black profile cable is used, if required. 

The maximum cable length per segment is 100 m but it can be extended using repeaters, for example.

Technical data

The field devices can be connected directly to the AS-Interface cable via a push-in connector. Piercing technology is used to connect the devices. During installation, two piercing needles attached to the cable pierce the insulation of the flat cable, thereby establishing a secure connection to the network. This technology ensures reliable connection and easy installation.

AS-i cable

Advantages of the AS-Interface cable

AS-Interface cable technology is valued for its simple, efficient and economical networking. The use of the AS-Interface flat cable for simultaneous power supply and data transmission makes it possible to avoid wiring errors.
In addition, this leads to a reduction in cabling and the associated installation costs.

 

Your advantages with AS-Interface

Our Bürkert expertise

We have been a reliable industry partner for many years and offer high-quality technology solutions. This also applies to the field of automation technology. An essential component of modern automation concepts is digital communication. As a member of the AS-International Association, we are actively involved in shaping this sector and certify our products and system solutions accordingly.
With the aid of AS-Interface, our products can be integrated into your plant when implementing an automation concept. Moreover, your individual requirements on the network topology can also be taken into account.
To provide you with the best possible support for the automation of your production plants, the communication protocol AS-Interface can be found in many of our applications and products.

 

 

Application examples with AS-Interface

Bürkert products with AS-Interface are generally used in process automation for controlling and regulating media (gases, liquids).  This includes processing plants for food production and packaging, as well as the beverage industry, dairies and application in the pharmaceutical sector.

Our control heads and positioners with AS-Interface

ASi-compatible products

Type 8691

Control head for decentralised automation of ELEMENT process valves

Type 8691
  • Contact-free inductive valve position registration (Teach-In function)
  • Coloured illuminated status display
  • Integrated control air routing in the actuator
  • Fieldbus interface AS interface, DeviceNet, IO-Link or büS (Bürkert System Bus)
  • With ATEX II cat. 3G/D / IECEx approval

Type 8695

Control head for decentralised automation of ELEMENT process valves

Type 8695
  • Contact-free inductive valve position registration (Teach-In function)
  • Coloured illuminated status display
  • Integrated control air routing in the actuator
  • AS-Interface, DeviceNet, IO-Link, Bürkert system bus (büS)
  • With ATEX II cat. 3G/D approval

Type 8681

Control head for decentralized automation of hygienic process valves

Type 8681
  • Universal attachment for hygienic process valves
  • Contactless position measurement system with 3 switching points (Teach-In function)
  • Coloured status display
  • Manual override operative with closed housing
  • AS-Interface, DeviceNet, IO-Link, büS/CANopen

Type 8694

Digital electropneumatic positioner for the integrated mounting on process control valves

Type 8694
  • Compact, robust stainless Steel design
  • Start-up by automatic TUNE-function
  • Contact-free position sensor
  • Integrated control air routing
  • AS-Interface, IO-Link or Bürkert System bus (büS)

Type 8694

Digital electropneumatic positioner for the integrated mounting on process control valves

Type 8694
  • Compact, robust stainless Steel design
  • Start-up by automatic TUNE-function
  • Contact-free position sensor
  • Integrated control air routing
  • AS-Interface, IO-Link or Bürkert System bus (büS)

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