Technological Foundations
AS-Interface
AS-Interface (short for Actuator/Sensor Interface) is an internationally recognized standard for field bus communication. With over 32 million nodes installed world-wide, it is heavily used at the sensor/actuator level of automation systems.
This simple wiring system consists of four components: the AS-i Master, an AS-i power supply, the yellow AS-i cable, and the AS-i slaves. Using piercing technology, sensors and actuators are connected directly to the AS-i cable. The unshielded two-conductor cable carries both power and communication, including safety signals. As a result, AS-Interface eliminates cumbersome parallel wiring. The AS-i Master controls the data communication on the network. As a Gateway it creates the connection between the AS-i network and the controller (e.g. PLC). The upper-level fieldbus treats it like a fieldbus slave. Integrating an AS-i network into an existing fieldbus or Ethernet system is no more complicated than adding any other I/O module.
Benefits of AS-Interface
AS-Interface offers the following benefits to the user
- Ease of use: The system can be operated and maintained with negligible training effort or specialized service personnel
- Free topology: AS-Interface allows cables to be routed according to the mechanical structure of the system (line, start, tree or ring structure)
- Fast, flexible installation and effortless expandability: New slaves can be added without error-prone and time-consuming cable assembly using piercing technology right on the AS-i cable
- Effortless integration of new slaves due to standardized profiles
- High availability and noise immunity
- Great savings on planning, installation, expansion, and service time compared to parallel wiring systems
- Certified products ensure manufacturer compatibility
AS-Interface installation
An AS-Interface installation using IP67 digital modules with M12 quick disconnects from Bihl+Wiedemann offers many advantages. The mounting base of the module contains two times two connections for the yellow profile cable. These connections enable a clean and well organized AS-i installation where up to four AS-i cable end caps and two passive distributors per module can be saved. Further information on the AS-Interface installation can be found in the section installation tips.
Safety technology using AS-i Safety at Work
Safety aspects play an important role in an increasing number of automation systems and designs – especially where personnel safety is at risk through hazardous movements. Safety-related requirements are documented for instance in the EU Machine Directive (Directive 2006/42/EC) or in the occupational safety regulations of various countries.
The Safety at Work concept of AS-Interface makes it possible to seamlessly integrate safety components, i.e. safety sensors and actuators, as well as safety monitors, into virtually any commonly used automation system. Compared to conventional safety solutions, the advantage of AS-i Safety at Work is the ability to send safe and unsafe signals over the same cable. This eliminates the previously required redundant infrastructure as well as the costs associated with complex and error-prone parallel wiring.
The AS-i safety components can be used just like any other standard slave at any location on the AS-i network in combination with standard AS-i components without any restrictions or limitations. The AS-i master treats the safety components just like any other normal AS-i slave. Safety sensors, safety actuators, and the safety monitor interact in a special communications environment.
AS-i Safety at Work is approved for applications with up to SIL3 safety requirements according to EN 61508 or PLe according to EN ISO 13 849-1:2006.
