Process automation with AS-Interface – versatile and convenient integration

AS-Interface (ASi) is the preferred solution for many process automation and process optimization sectors. These include in particular the food industry, glass and steel production, chemicals and pharmaceuticals. However, users in the fields of process engineering, control engineering and control technology can also benefit from AS-Interface.


The proven advantages of AS-Interface include the transmission of data and power via just one cable, simple wiring using piercing technology and great freedom in the choice of topology. You can also benefit from numerous other ASi advantages in process automation.


A wide selection of ASi-5 valves is available for process technology, e.g. from GEMÜ or SPX FLOW. These generally provide you with many additional diagnostics and parameters for process data so that your system is ideally equipped for Industry 4.0 requirements. Of course, many other modules for different tasks are available with ASi. They can be used to easily integrate digital and analog inputs and outputs, IO-Link sensors or serial protocols such as RS232. ASi also makes it possible to implement cost-saving safety technology on the same two-wire cable. For instance, AS-Interface can be used to safely monitor analog signals such as temperature, pressure, or fill level simply, reliably and, above all, cost-effectively.

Process automation – advantages at a glance

for Industry 4.0

With ASi-5, you benefit from detailed diagnostics and numerous parameterization options. Additional information can also be read out in parallel with process data. Our ASi-5/ASi-3 Gateways also offer modern interfaces such as OPC UA or REST API and, thanks to FIMLET, enable integration into FIM.

Cost savings
with ASi-5

The functionalities of the valve heads with integrated ASi-5 are comparable to the respective IO-Link solutions. However, you will not need to use any additional master ports or IO-Link communication. If you still want to use IO-Link devices in the application, you can use our convenient, cost-effective IO-Link masters. Compared to Ethernet-based solutions, With ASi, you enjoy the benefits of significantly less connectors and cables.

Convenient integration of components from different manufacturers

Commissioning, configuration and diagnostics of ASi networks is very easy and convenient with the Bihl+Wiedemann Software Suite. It is even possible to fully integrate components from other manufacturers.

Ensuring compliance with important documentation requirements

Using the IIoT connection via IT interfaces such as OPC UA and Rest API, it is possible to ensure that parameter changes are recorded and logged. This ensures compliance with the documentation requirements that are necessary in some sectors of process technology.

Numerous options for integrating valves

With AS-Interface, sensors and actuators are integrated seamlessly into the communication bus – all without the need for additional cables via digital I/Os.


This means that our active distributors with integrated ASi connection can be used to make any sensors and actuators ASi-capable (ASi in the distributor). You can connect sensors and actuators that are already ASi-capable anywhere in the field using compact passive distributors (ASi in the sensor). Find out here how you can easily integrate a wide range of components into ASi.


ASi-5 allows IO-Link sensors to be controlled directly via ASi. This enables process data such as temperature or pressure to be communicated and parameterized in real time. With AS-Interface, the valves can be placed anywhere along the ASi cable.

Integration into virtually any control system

AS-Interface can be used regardless of the system and manufacturer. By supporting all common fieldbus systems, functional safety stays absolutely unchanged, regardless of the control system used. This means that many applications can be implemented easily and cost-effectively.

Saving wiring costs

As a rule, AS-Interface wiring is performed using piercing technology with branches for the valves used. However, this is not always possible. Other safety precautions must be taken in explosion-protected zones (ATEX Zone 2 or Class1 Div 2) or in exposed areas of the food industry (IP69k). In such special environments, the use of distribution boxes and ASi via round cables in combination with certified ASi nodes is the ideal solution.

Cost reduction by eliminating expensive master ports

In process automation, both IO-Link and AS-Interface are ideally suited for a wide range of applications. ASi-3 is the ideal solution for many standard applications because it is cost-effective and easy to integrate,


Whereas, ASi-5 can really come into its own with more complex applications. In terms of functionality, ASi-5 can be compared with an IO-Link solution. However, with ASi-5 you will always avoid the costs associated with the master port and IO-Link communication. That is because the ASi-5 connection is integrated directly into the device.

Further advantages of ASi-5 in process automation

  • Over 100 devices on just one gateway

  • Transmission of 2 to 32 bytes of process data per module

  • Parameter image configuration with parameters up to 128 bytes

  • Detailed diagnostics in the event of an error

  • Additional information can be read in parallel to the process data if required

IO-Link and ASi-5 – same convenience, greater diagnostic options

Extra information can play a decisive role when it comes to process technology – not only with respect to possible wear, but also for predictive maintenance or to analyze external effects on process stability. Many sensors or actuators such as valve heads can easily capture this information in addition to the process-relevant data. Thanks to a wiring technology with a 2-wire cable for power and data, it is very convenient to physically integrate such "smart devices" with ASi. The interface of the smart device is virtually irrelevant because ASi-5 offers the option of integrating many different protocols, e.g., IO-Link. The direct connection of ASi-5, for example in the valve head, is still the most efficient way.

Convenient integration with the Bihl+Wiedemann Software Suite

The Bihl+Wiedemann Suite (BW2902) and the Bihl+Wiedemann Safety Suite (BW2916, BW3065) are two software packages used for commissioning, configuring and diagnosing ASi networks. The software can also be used to fully integrate components from other manufacturers. The technology used is irrelevant. It doesn't matter whether it's IO-Link, ASi-5, various different drive manufacturers or serial protocols. The Bihl+Wiedemann Software Suite allows you to configure, parameterize and commission virtually all devices required for process automation. Above all, the additional information provided by the device can be easily read and interpreted thanks to the graphical user interface and plain text messages.

IIoT connection ensures compliance with documentation requirements in the pharmaceutical sector

The extended diagnostic options offered by ASi-5 can be used for modern IIoT and Industry 4.0 applications. The most important IT interfaces such as OPC UA and REST API plus drivers in specialized systems such as ABB's Field Information Manager (FIM) are available for this purpose. They serve to record and log parameter changes, as is required in the pharmaceutical sector. This ensures that the important documentation requirement is met.

Functional safety in process automation

Safety applications in the functional safety sector can also be implemented with AS-Interface. This ranges from classic E-stop buttons, safety doors and light barriers to safe monitoring of temperature and pressure. The big advantage: safe and standard signals can be transmitted on the same two-wire line. This eliminates the need for costly duplicate infrastructure.


More Information

Proven in practice many times over – process automation with AS-Interface

Find out how other customers have already successfully implemented AS-Interface in process technology and how it enabled them to drastically reduce installation expenses and wiring complexity.

The brewery, which recently opened in April 2019, was designed and built by the brewery experts GEA Process Engineering A/S. All the brewery’s processes including ASi Masters and motors are controlled via PROFINET by two Siemens PLCs. All the brewery’s processes including ASi Masters and motors are controlled via PROFINET by two Siemens PLCs. All the tanks, kettles and plant components can be mutually connected by means of a system of 744 pneumatically activated process valves – controlled by eight ASi Masters from Bihl+Wiedemann. The ASi network also links together instruments and sensors that record the process data from each fermentation tank, such as the pressure, level and temperature.

Like most, the process industry is under intense cost pressure. For years, AS-Interface has been succeeding in reducing installation costs. The introduction of ASi-5 technology provided additional features to increase plant performance significantly. The strategic business units are pharma, food and biotech, industry, semiconductors, and medical.


Source: ASiMAG issue 2023-E2

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