AS-Interface – Automation made simple

• Over 40 million ASi devices in use worldwide
• Over 7 million of them are safety devices
• More than 2,000 certified products
• Almost 70 % growth with regard to safety-oriented devices

The AS-Interface master connects sensors and actuators to the higher-level control via the ASi modules. With the ASi Master, digital and analog data that has been gathered decentrally by ASi modules, can be transferred to the higher level control through the respective bus system. The output signals of the controller are transmitted then through ASi to the actuators in the field.

More about ASi Master

ASi nodes are connected to the ASi Master with a cable. They are used to integrate the sensors and actuators into the ASi network, regardless ifinside the switching cabinet or in the field. These are connected to the power supply and data communication in the ASi network. Each node is assigned to a unique address in the network.

More about ASi nodes

The ASi cable is an unshielded, 2-core cable. It not only transmits data and power, but also enables easy and cost-effective installation. Thanks to piercing technology, participants can easily be installed on the profiled (thus reverse polarity protected) ASi cable – with perfect contacting and achieving protection class IP67. An additional 24 V supply is possible without problems.

More about ASi cable

The ASi cable is specified in the ASi standard (IEC 62026-2 or DIN EN 62026-2).

An ASi wire stripper is used for stripping ASi cables with an outer insulation of thermoplastic elastomer (TPE) or polyurethane (PUR).

The sensors or actuators are usually connected by means of piercing technology. In this process, the insulation of the flat cable, which is profiled to protect against reverse polarity, is pierced during installation by two piercing pins without the cable needing to be prepared beforehand. In this way, nodes can be relocated or added directly on the cable at any time without major installation effort.

Addressing of ASi-3 nodes

With ASi-3, there are 31 ASi addresses available, whereby each address may only be allocated once. A distinction is made between standard addressing and extended addressing. The addressing mode of ASi participants is determined by the manufacturer. With standard addressing, each ASi participant reserves a full address (1..31). With extended addressing, each address can be reserved by two ASi participants (1A..31A, 1B..31B). It is not possible to address an ASi node with standard addressing and an ASi participant with extended addressing on the same address, e.g. 3 and 3A or 3B.

Addressing of ASi-5 nodes

With ASi-5, the nodes are assigned an ordering number starting from 1. The numbering takes place sequentially.

In conventional design, a separate ASi power supply (with integrated decoupling coils) is required for the voltage supply of each ASi circuit. With ASi gateways and safety monitors of the version "1 power supply, 1 gateway for 2 ASi circuits, cost-effective power supplies" by Bihl+Wiedemann, the decoupling coils are already built into the devices. This enables the supply of two ASi circuits by means of one standard 30 V power supply.

With short cable lengths, even a standard 24 V power supply can be used. This is an optimal solution for small and very small systems – i.e., for small machines with 3 to 15 ASi nodes and a maximum cable length of 50 meters. We have an affordable line of ASi gateways, optimized for 24 V applications.

ASi distributors enable simple connection of various sensors and actuators to ASi anywhere in the field over an M12 connection. Active distributors are required for sensors and actuators without an integrated ASi chip. Passive distributors are suitable for sensors and actuators with an integrated ASi chip.

The total length of the ASi standard network is limited to 200 m for ASi-5 and 100 m for ASi-3. When determining the total length, all junctions must be included in the calculation. The ASi bus termination is a cost-effective module for extending the cable length in an ASi-3 network up to 200 m.

This diagram shows the basic structure.

For mixed ASi-5/ASi-3 circuits, we recommend an additional ASi bus termination if the cable length is approx. 70 m or longer. The ASi bus termination can help improve the ASi-5 communication.

The total length of the ASi standard network is limited to 200 m for ASi-5 and 100 m for ASi-3. To determine the total length, all junctions must be included in the calculation. The ASi repeater is a module for cable extension. It makes it possible to increase the cable length in an ASi-3 network up to 200 m. Areas with strongly impaired EMC can thus be bypassed. ASi repeaters cause a certain delay in the transmission of telegrams.

This diagram shows the basic structure.

More about ASi line extension

ASi-3 is a proven and stable technology with a wide range of available products. However, ASi-3 continues to be a future-proof technology whose possibilities are far from being exhausted. In the course of digitalization and Industry 4.0, it is now necessary to retrieve more and more data more quickly from the field level - in order to subsequently process them in higher-level instances. ASi-5 was developed for this requirement: The latest ASi generation offers a correspondingly high data bandwidth and short cycle times.

ASi-3 and ASi-5 are compatible with each other and complement each other optimally. Depending on the application or requirement, it must be checked individually which ASi technology is when the most appropriate or most economical. In practice, there will mostly be applications in which both ASi technologies are used. ASi-5 will therefore not replace ASi-3.

ASi end caps are used to protect the bare ends of the ASi or AUX profile cable against dust and humidity up to max. IP67 – for interference-free communication in the ASi circuit. They are available as left and right versions. Many Bihl+Wiedemann nodes and active distributors do not generally require the use of end caps because the cable ends can be terminated in the base.

The total length of the ASi standard network is generally limited to 100 m. When determining the total length, all junctions must be included in the calculation. However, the length can be increased, for example, to 1,000 m by means of repeaters, bus terminations and/or ASi tuners.

More about ASi line extension