Each of the electrical component has variables corresponding to the domain being modeled. Electrical components have voltage and current. The voltage corresponds to the difference of potential between the positive and negative pin (across the component), whereas the current corresponds to the amount of charge going through the component.
Two properties v and i are created in TwoPinComponent. During the simulation, the voltage and the current will vary over time. As a result, the properties need to be stereotyped by PhSVariable. Their type must be a ValueType that has a unit with a symbol. Voltage and Current are already provided by the simulation library, so they can be selected (remove filters if necessary). The resistor has an additional property - the resistance. A property r is created in the resistor. Since the resistance will not change during the simulation, the property needs to be stereotyped by PhSConstant. It is necessary to create a new ValueType called Resistance that will serve as a type for this property. It must have a corresponding SysML Unit with a symbol set to Ω. Additionally, it must be a specialization of SysML Real.
The image below shows how Block Definition Diagram (BDD) should look like at this point.
