AS-Interface sensors - System description

Intelligent sensors · Introduction
In 1994 ifm electronic presented the first intelligent AS-i sensors worldwide at the Hanover Trade Fair. Remote parameter setting via the bus and transmission of diagnostic messages to the controller were already possible. On the basis of this experience and due to new innovative sensor technologies it was possible to make AS-i sensors with a built-in interface smaller and more powerful. As for the housing types there is no difference any more to simple units with a binary switching output. So for sensor installation you have to take into account if it is a binary, analogue or an AS-i sensor - this is indicated on the type label.

When defining sensors with a built-in interface three levels are differentiated:
  • Sensors without a built-in interface
  • Sensors with diagnostic information
  • Sensors with a built-in interface
On the first level the sensors are connected via bus modules with standard signals (24 V switching signal, 0...10 V or 4...20 mA analogue signal). The advantage of this method is the large range of sensors without a built-in interface on the market and many I/O modules for all kinds of application. A disadvantage is certainly the restricted monitoring of the sensor function. On level 2 there are sensors with serial interfaces or bidirectional function check pins which can also be connected to specialised bus modules. Advantages are extended diagnostic possibilities, disadvantages are the interfaces specially adapted on the sensor and controller side. The optimum solution are AS-i sensors with a built-in interface on the third level of development. For AS-i sensors digital or analogue values can be transmitted. The AS-i sensor interface is standardised to IEC 62026-2. The most important sensor profiles as part of the AS-i specification ensure interoperability.

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System overview — AS-Interface sensorsSelector — AS-Interface sensors

Inductive sensors on a carriage