Understanding Smart Sensors - Nomads.usp

280 Understanding Smart Sensors• Publish on publisher port objects;• AddSubscriber and an associated callback operation on subscriber portobjects.The publisher and subscriber use a combination of domains, keys, andtopics/qualifiers (defined in the standard) to allow only the publications ofinterest to a subscriber object to be selected from publications received by asubscriber port [2].12.3.3 The IEEE 1451.1 ExampleAn example of how the NCAPs for sensors and actuators could be establishedfor a wastewater treatment system is provided in the appendix of 1451.1. Thatexample provides a rigorous implementation of the standard. Identifying theNCAPs is one of the initial steps. The system diagram in Figure 12.7 shows aPump speed control:analogMixer control:digitalNaOHPumpMixerWaste waterDatabaseLevel sensor:analogValve control:analogSewerLevelpHpH sensor: analogPump controlValve controlMixer controlAlarmsSet setpointsOperator stationFigure 12.7 Wastewater treatment system example. (After: [2].)