This information is part of the Modelica Standard Library maintained by the Modelica Association.

Package Sensors consists of idealized sensor components that provide variables of a medium model and/or fluid ports as output signals. These signals can be, e.g., further processed with components of the Modelica.Blocks library. Also more realistic sensor models can be built, by further processing (e.g., by attaching block Modelica.Blocks.FirstOrder to model the time constant of the sensor).

For the thermodynamic state variables temperature, specific enthalpy, specific entropy and density the fluid library provides two different types of sensors: regular one port and two port sensors.

• The regular one port sensors have the advantage of easy introduction and removal from a model, as no connections have to be broken. A potential drawback is that the obtained value jumps as flow reverts.
• The two port sensors offer the advantages of an adjustable regularized step function around zero flow. Moreover the obtained result is restricted to the value flowing into port_a if allowFlowReversal is false.

Modelica.Fluid.Examples.Explanatory.MeasuringTemperature demonstrates the differences between one- and two-port sensor at hand of a simple example.

• 22 Dec 2008 by R;uumldiger Franke
  
  • flow sensors based on Interfaces.PartialTwoPort
  • adapted docu to stream connectors, i.e., less need for two port sensors
• 4 Dec 2008 by Michael Wetter
  included sensors for trace substance
• 31 Oct 2007 by Carsten Heinrich
  updated sensor models, included one and two port sensors for thermodynamic state variables