actuator sensor interface (AS-i)
The AS-Interface, Actuator Sensor Interface (AS-i), is a sensor- actuator network that connects the actuators and sensors via a 2- wire line. Via this 2-wire line the control signals and the user data for the components are transmitted, the configuration data for the system architecture and the monitoring data for intelligent components and the network, but also the supply voltage of 24 V for the components.
In terms of concept, the AS-Interface corresponds to a simple, cost-effective fieldbus in master- slave operation at field level, which is easy to install and optimized for binaryperipheral devices, for actuators and sensors. Peripheral components can be added or disconnected directly.
The AS-Interface networks automation components at the field level up to the control level. It is mainly used in Europe, especially in Germany.
Up to 62 nodes can be connected to the AS-Interface, which are permanently monitored by the master station. The cycle time depends on the number of slaves and adjusts automatically. With six slaves it is 1 ms, with 62 slaves 10 ms. The length of the AS-Interface is 100 m and can be extended up to 300 m with three repeaters. The data rate is 167 kbit/s. Topologically, an AS network can be very flexible and allows configurations in star topology, bus topology, tree topology and linetopology.
Special unshielded 2-wire cables are available for the AS-Interface, which can be connected with reverse polarity protection. Up to 8 A can be transmitted via them. The cable connection is a mandrel, which pierces the insulation of the cable when it is connected and makes contact with the cable core. For identification purposes, the cable sheaths are color-coded: light blue indicates the negative supply line, brown the positive.