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Building Automation with ASi

The advantages of AS-Interface have now become familiar in Building Automation as well. The following overview shows the simple, cost-saving installation, and the high degree of flexibility of this industrial networking solution for automation systems:

AS-Interface – Building Automation

The advantages of AS-Interface – such as simple, cost-saving installation and high degree of flexibility – have now become familiar in Building Automation as well. Numerous companies are relying on the ASi installation system for applications such as controlling fire and smoke damper systems, shutter drives or heating and cooling ceilings using analog output modules. Damper actuators with flow regulators can also be connected to the controller through the MP-Bus Gateway. It is also possible to process EnOcean signals from wireless buttons and sensors through ASi. Customer proximity is our hallmark, which means we stand by you in word and deed and are open to custom-tailored solutions. Just contact us.

Basic Concept of AS-Interface 

AS-Interface is an industrial networking solution for automation systems. It is designed for connecting simple field I/O devices such as binary ON/OFF, analog and safety I/O devices according to EN 50295, IEC 62023-2. Using only a two conductor flat or round cable (ASi cable, 2 x 1.5 mm2, 16 AWG) to connect all nodes to the master using a free topology. This is the main advantage of this system compared to conventional, parallel wiring, where every single signal has to be wired directly to the control system.

Data and power are available in the same ASi cable . Every node or module has its own address for accessing its data. The nodes can be addressed from 1 to 31 (single address, or, with extended addressing, there are 62 addresses available (1A to 31A and 1B to 31B). Single addresses and modules with extended addressing (AB modules) can share the same network.

The Structure

The ASi Master/Gateway controls the ASi network and acts as a direct link to the host (PLC, Building Management Systems, etc.). Combined with an integrated mini-PLC functionality the master can also be used for pre-processing or as a stand-alone device without the need for a host controller (programming language IL or C).

A Gateway is an ASi Master, and simultaneously a node to higher level network ( PROFIBUS , EtherNet/IP , Modbus , etc.). AS-Interface is the lowest level of the automation pyramid intended for Actuator/Sensor networking.


Free Topology

ASi supports free topology such as Star, Ring, Linear, Tree and Mesh network (see examples below).

Tree topology

Ring topology


The simple and highly flexible ASi network bus is one of the great strengths of the system. The polling  principle allows the use of any topology and features a variety of different field and control cabinet modules. Whatever the requirements in your building we make it possible to record both digital and analog values and control either type of actuator. Whether a ventilation flap with four digital and four analog outputs, an analog output module for controlling heating/cooling ceilings, or special equipment such as an MP-Bus or EnOcean gateways.

You can also process both ASi standard and ASi Safety (up to SIL3) data over the same ASi network. The data can be processed in the master or passed on to the higher level building management system through the fieldbus interface on the master.

ASi Features per line


Unshielded two conductor flat cable *


Power Supply and data in one cable with max. 8 A

Number of Nodes per ASi line

up to 62

Number of I/O Binary

up to 248 Inputs and 248 Outputs

Number of I/O Analog

up to 124 Inputs or Outputs

Cycle Time

5 ms

Transmission Rate

167 kbit/second

Error Protection

Identification and repetition of faulty frames

Supported Topology

Tree, Star, Ring, and Linear


Up to SIL 3, Category 4, PLe (EN 62061, EN 61508, EN ISO 13849-1, EN 954-1)

Cable Length

100 m (extensible up to 1000 m)

* Of course other cables, such as NYM-J or E90 cable, can also be used.


Gateways for linking to any Building Management System

Optionally with integrated controller (mini-PLC) also usable as stand-alone devices

  • Permanent line path monitoring
  • Plain text messages on the display and to the BMS
  • Pre-parameterized on request

Power Supplies

  • Single phase
  • 3 phases
  • 24 V to ASi
  • 1,8 A, 2 A, 4 A, 8 A
  • Decoupling unit for 2 ASi networks

    Module for controlling damper actuators

    • For ventilation, fire and smoke dampers
    • Inputs for end position detection
    • Additional input e.g. for fire alarms
    • Output for controlling dampers
    • Supply of the drives from ASi or external 24 V

    Module for increased safety requirements

    • For ventilation, fire and smoke dampers according to Swiss standard for soldered strut and fire alarms
    • Inputs for end position detection
    • Control up to SIL 3/Cat. 4/PLe
    • Supply of the drives from ASi or external 24 V

    Module for controlling
    shutter drives

    • 2 shutter drives (230 V AC) per module controllable
    • 4 inputs for switches
    • For 4-/5-conductor-shutters
    • Trip-/position recognition

    Relay Module for field applications (230V/24V)

    MP-Bus Gateway

    EnOcean ASi Wireless Module

    • For linking EnOcean wireless modules (e.g. pushbuttons, temperature sensors, window contacts, presence detectors) to ASi
    • Available in individual designs

    • ASi Safety Module to Control  Fire/SmokeDamper Actuators (up to SIL 2)

    • Mixed Input / Output Modules
    • For floating contacts, OSSD outputs and safety mats
    • Electronic outputs
    • Relay outputs

    • Speed/Standstill monitoring

    Digital and Analog Input and Output Modules

    In Stainless Steel,

    For example:

    • Digital 4I/4O
    • Digital 8I
    • Digital 8O
    • Relay outputs (230 V AC)

    In surface-mounted box,

    For example:

    • 2 analog (0-10 V) + 2 digital outputs for heating/cooling ceilings
    • Digital 4I/4O
    • Input Modules for CO2, relative humidity, etc.

    Coated module for
    flush-mounted boxes

    • 4 digital inputs for standard switches





    Cabinet modules

    • 4E/4A, 8E/8A
    • 0/4...20 mA
    • 0...10 V
    • Pt100, Pt1000
    • Thermocouples

    • Digitale I/O Modules
    • Pt100, Pt1000
    • Analog  I/O Modules



    Diagnostics/Circuit extension

    Benefits at a glance


    • Save hardware by reducing I/O cards, cabinets and wiring
    • Robust, globally standardized industrial bus with already more than 27 million installed nodes
    • Simple electronics with robust performance in industrial quality
    • Free choice of network topology
    • Quick installation, reduce maintenance and shorten testing time,fast commisioning and ability to expand the system
    • Easy commissioning, and opportunity to expand the system
    • Transmission in real-time
    • Avoid wiring errors (no risk of faulty electrical connection)
    • High resistance against EMC noise
    • Fast error localization, spontaneous diagnostics and enhanced diagnostic options


    ASi is fully backwards compatible. This means that a master according to the last specification 3.0 can communicate with all existing nodes according to the different specifications 2.0, 2.11 and 3.0. This guarantees a future proof investment.

    Simply to connect

    Owing to the yellow profile cable* and the piercing technology, ASi modules are easily expandable and can be connected reverse polarity protected.


    * Of course other cables, such as NYM-J or E90 cable, can also be used.

    This could also be of interest to you

    Control of Fire Dampers and Smoke Extraction Dampers

    Find out how you can reduce fire loads in the building by up to a factor of 30 with ASi. Thanks to the ASi profile cable, fire dampers and smoke dampers can be supplied with data and energy via a single two-wire cable.


    The standardized fieldbus system AS-Interface (ASi) helps you drastically reduce your wiring complexity. You also benefit from free choice of topology and cost-effective integration of safety features on the same infrastructure.

    Products for Building Automation Available in the Web Shop

    ASi advantages, such as freedom of topology, extremely simple installation or high flexibility, have also become widely adopted in building services engineering. Here you will find our wide range of products.

    Questions about our products and solutions?