Safety at Work Installation Certification Applications

Functional Safety Technology

AS-Interface Safety at Work

Why AS-Interface?

Automation is simply easier and faster with AS-Interface. The system’s connectivity reduces labor as well as expenses and supports the advantages of decentralized installations. In numerous applications, AS-Interface is the proven standard for networks.

Currently, more than 44 million AS-Interface devices are in operation. The system uses Safety at Work technology to provide functional safety.

AS-Interface provides an efficient connection to modern control systems for devices, switches, sensors and actuators. The system uses a two-conductor cable that handles communication and power supply. Components can be connected quickly and easily, at any location and at any time using piercing technology. This fast and easy to use technology reduces installation, system, and maintenance costs.

Automation developed from needing a large number of contact points connected by a large number of cables to using just one single cable. This cable links everything and is simply directly connected, significantly reducing time for wiring and errors.


up to 60% cost reduction possible with AS-Interface


AS-Interface in the World of Modern Automation

As digitalization advances the importance of the availability of the components’ device data increases. AS-Interface is an established technology to cost-efficiently connect the devices on the network to the control system that can be located in a variety of different systems. The components’ data are consistently available in host systems and cloud applications. AS-Interface’s main advantage is the easy and ideal connectivity, especially from a cost point of view.

Operational advantages:

AS-Interface System Components

The AS-Interface shadow logo indicates that a device is certified by the independent AS-Interface testing center. Therefore, devices from different manufacturers can be operated effortlessly on a single AS-Interface network.

To add safety switches to an AS-Interface network, the following components are required:


AS-Interface Safety at Work

AS-Interface Safety at Work enables wiring a system up to category 4 performance level e according to EN ISO 13849 or up to SIL 3 according to IEC 61508, respectively. The system designer determines the correct combination of safety components and sets up the safety monitor configuration according to the selected control category. With appropriate component selection, performance level e, category 4 can be achieved. Testing of all safety functions is mandatory.

The safety monitor works like a safety relay. The safety monitor or the safety controller have output circuits that include two redundantly constructed release circuits and can, in general, be used up to control category 4 performance level e. The safety monitor’s functions by far exceed those of a single safety relay due to additional integrated safe logic modules. Depending on the application, a single safety monitor can replace several conventional safety relays, significantly reducing wiring and saving space in the control cabinet.

To achieve the preferred safety category, the designer needs to ensure that the safety components and the associated safety functions are coordinated and documented accordingly during safety monitor configuration. The safety monitor’s specific functions perfectly support the functional safety engineer’s work.


Master-Gateways, Components, Power Supplies, Accessories

The master organizes communications on the AS-Interface network. From a technical point of view, the master provides the components’ data without safety function. A master feeding data into another network is called a gateway.

Foremost, all devices on the network communicating through AS-Interface are system components. There are safe components for functional safety, achieving special requirements essential to the respective safety standards. Then there are components that provide or react to control data. These components are devices, sensors, actuators or modules.

On the network, the AS-Interface power supply has several tasks. It provides power to all components and it contains the so-called data decoupling.

Data decoupling is necessary to generate communication signals on the network that are particularly robust against interferences. The power supply provides power to components and their electronics. In addition, power supplied via AS-Interface can also be used to provide 24 V at the components’ outputs.

A wide range of accessories is offered for AS-Interface, from addressing and diagnostic devices to suitable accessories for cable installation. AS-Interface cables are available in various sheath materials to meet typical requirements concerning flame and oil resistance or flexibility.