ABSTRACT
AS-Interface (AS-i) (actuator/sensor interface) was defined and developed by a consortium of 11 German and Swiss companies between 1990 and 1994. AS-i Is the fieldbus for the lower levels of the information pyramid in industrial automation technology, with a broad range of applications in factory automation, process automation, building automation, and mobile equipment automation. The AS-i master provides the device data to the control unit. The AS-i transfers data and energy on a two-conductor cable; the two conductors are usually named AS-i+ and AS-i–. But AS-i– is different to the ground (GND), well known in direct current technology. The specification divides the master into three layers, which describe the master from the AS-i cable to the host interface. An important task of all the layers is the handling of errors, or not normal operating states, without sending false sensor or actuator signals. The master call data call (data exchange) is the most important and frequently used AS-i call.
