Sensor Plug In Plug-and-measure Support

SANY D2.3.4 Specification of the Sensor Service Architecture V3 Doc.V3.1 Copyright © 2007-2009 SANY Consortium Page 222 of 233 In the following, some of the major steps in supporting plug-and-measure functionality are described. They are illustrated in Figure 10-37.

10.12.1 Sensor Plug In

The concepts and mechanisms described in the following concentrate on the deployment of a new smart sensor in a sensor network controlled by a station compu ter, where “new smart sensor” means a new instance of a sensor type initially unknown to i.e. not registered with the measurement station. A smart sensor is considered to be a sensor that provides a certain amount of processing and storage ability that can be connected to the station, meaning that both sensor and station computer have to support the same communication technology e.g. USB, ZigBee, IEEE1451, CAN-BUS and the necessary hardware and software layers have to exist in order to enable simple byte stream communication between the two. Figure 10-37: Plug-and-measure Component Interaction Upon plug-in connection on the hardware level the application layer on the measurement station has to become aware of the new sensor e.g. through a notification mechanism. Considering the rather large number of existing technologies at this level it is impossible to provide a generic approach to how this should be accomplished. Two prominent patterns can be identified though: SANY D2.3.4 Specification of the Sensor Service Architecture V3 Doc.V3.1 Copyright © 2007-2009 SANY Consortium Page 223 of 233 1. The “sensor triggered plug-and-measure” pattern implies that the station computer passively listens for new sensors and is notified when a new sensor is connected. To illustrate this consider the case of a USB sensor connecting to the USB subsystem of the station. Upon connection the USB subsystem fires an interrupt that is propagated through various software layers, eventually translated into a notification and caught by the station computer sub-process handling new sensors. 2. The “station triggered plug-and-measure” pattern implies that the station actively polls for new attached devices. This can easily be imagined for the case of simple bus technologies like CAN-BUS.

10.12.2 Sensor recognition and connection establishment