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24 Volt AS-i

Cost-Effective Solution for Small Systems


What is AS-Interface?

AS-Interface is a globally standardized fieldbus system (EN 50295 and IEC 62026-2). It is a system that links sensors and actuators to a controller over a common data transmission path.

Data and power through a single cable

The abbreviation AS-i stands for Actuator-Sensor Interface. This interface connects the modules in the lowest process level in automation systems with each other. The usual cable trees are replaced here by a single electrical cable – the AS-i cable. This cable carries both data and power.

The four AS-i components

Leading manufacturers around the world support this simple wiring system. It consists of four components: the master, the slaves, a power supply and the yellow AS-i cable. Each slave has a unique address assigned to it which the master used to exchange in- and output data.

Power for AS-i

AS-i modules are generally powered by an additional power supply having a rating of 30 volts.

Small systems can eliminate the power supply

Bihl+Wiedemann now offers masters which can be connected to already present standard 24 V power supplies, without the need for an additional AS-i power supply. This is an ideal solution for small machines having three to 15 slaves and a maximum cable length of 50 meters.

24 Volt AS-i overview

  • Ideal for small and very small applications (around 3-15 slaves)
  • No additional AS-i power supply needed
  • Can be powered directly by the 24 V already present in the control cabinet
  • Maximum 4 A available for AS-i
  • Up to 50 m AS-i cable length
  • Interfaces with all common fieldbus systems

Maximum Cable Length 50 Meters

AS-i with 24 V standard power supply

AS-i with 30 V power supply

V = R × I
Voltage = Resistance × Current


The longer the AS-i cable, the greater the resistance. This means for 24 Volt AS-i that a cable length of 50 meters should not be exceeded, since otherwise the voltage drops too low.

Ideal for a Handful of Slaves

24 Volt AS-i is economical for just three or more modules

Save with 24 Volt AS-i

  • Save space

The 24 Volt AS-i system saves valuable space in the control cabinet since the existing standard power supply can be used.

  • Save time and effort

With 24 Volt AS-i the documentation and installation time is reduced. Simply connect the 24 Volt AS-i Gateway to an existing power supply – that's it.

  • Reduce costs

24 Volt AS-i saves money since no additional AS-i power supply is needed. This also means a circuit breaker can be eliminated.

Questions about our products and solutions?