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Absolute Reference (MA)

(Not recommended) Reference point at zero absolute temperature and pressure

Using this block is no longer recommended. Instead, make absolute measurements by setting the Measurement reference parameter of the Pressure & Temperature Sensor (MA) block to Absolute. (since R2023a)

  • Absolute Reference (MA) block

Libraries:
Simscape / Foundation Library / Moist Air / Elements

Description

The Absolute Reference (MA) block represents an absolute reference for the pressure and temperature in a moist air network. At port A, the pressure and temperature are equal to absolute zero. Specific humidity and trace gas mass fraction are also equal to zero.

Unlike other domains, where each topologically distinct circuit within a domain must contain at least one reference block, moist air networks do not have this requirement. For more information, see Reference Node and Grounding Rules.

The purpose of the Absolute Reference (MA) block is to provide a reference for the Pressure & Temperature Sensor (MA). For example, to measure the absolute pressure and absolute temperature of a node, connect that node to the A port of a Pressure & Temperature Sensor (MA) block. Connect the B port of the Pressure & Temperature Sensor (MA) block to an Absolute Reference (MA) block.

If you use the Absolute Reference (MA) block elsewhere in a moist air network, it triggers a simulation assertion because air mixture pressure and temperature cannot be at absolute zero.

Examples

Ports

Conserving

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Moist air conserving port where the pressure and temperature are equal to absolute zero, and specific humidity and trace gas mass fraction are equal to zero.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2018a

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R2023a: Absolute Reference (MA) block no longer recommended

The Pressure & Temperature Sensor (MA) block now contains an implicit reference node, which means that you need only one port to make absolute measurements of pressure or temperature. Expose the second port only if you need to measure the difference in pressure or temperature between two nodes in the model.

In previous releases, to measure the absolute pressure and absolute temperature at port A, you needed to connect port B to an Absolute Reference (MA) block. This is no longer necessary because you can now make absolute measurements by setting the Measurement reference parameter of the Pressure & Temperature Sensor (MA) block to Absolute.

This change has no compatibility impact. Existing models that have an Absolute Reference (MA) block connected to a Pressure & Temperature Sensor (MA) block continue to work as before.