Implicit versus Explicit Connection Structures

An implicit connection structure has the nice property that additional components can be added to the structure without the need for additional explicit connections. A new component becomes automatically connected to the system.

Consider the CircuitBoard Modelica code below. New components added to the compvec vector within the compTwo model instance become automatically connected. The reason is that all outer envHeat connectors within the compvec vector automatically reference the inner envHeat definition connector declared in the CircuitBoard.

connector HeatPort Modelica.SIunits.Temp_K T "Temperature in [K]"; flow Modelica.SIunits.HeatFlux q "Heat flux"; end HeatPort;
model Component "Component within a circuit board in an environment" outer HeatPort envHeat; // Reference to environment heat interface HeatPort heat; // Local heat connector of component equation connect(heat, envHeat); end Component;
model TwoComponents "Two Components together" Component compvec[2]; end TwoComponents;
model CircuitBoard inner HeatPort envHeat; // Definition of environment heat interface Component comp; TwoComponents compTwo; end CircuitBoard;

Explicit Connection

As a comparison we show the same example modeled using traditional explicit connections depicted in with corresponding Modelica code below.Each time we add a new component to the compvec vector in the compTwo instance, an additional explicit connection has to be added into the TwoComponents class as a connect-equation

connector HeatPort Modelica.SIunits.Temp_K T "Temperature in [K]"; flow Modelica.SIunits.HeatFlux q "Heat flux"; end HeatPort;
model Component HeatPort heat; end Component;
model TwoComponents Component compvec[2]; HeatPort heat; equation connect(compvec[1].heat, heat); connect(compvec[2].heat, heat); end TwoComponents;
model CircuitBoard HeatPort envHeat; Component comp; TwoComponents compTwo; equation connect(comp.heat, envHeat); connect(compTwo.heat, envHeat); end CircuitBoard;