Subsystem Definition
The Subsystem Definition () feature is used to define subsystems, which can be inserted as components into the main system using a Subsystem Instance node. Create the subsystem by adding subnodes to the Subsystem Definition node.
It is possible to add all types of two port and single port components within a subsystem definition. It also allows to add subsystem instance within a subsystem definition in order to create nested subsystems.
Name
Enter a component Name for the subsystem definition. The default name (for the first instance) is sub1.
Node Connections
Define the number of connecting nodes by adding more nodes or deleting existing nodes and set the Node names at which the subsystem connects to the main system or to other subsystems. The order in which the Node names are defined is the order in which they are referenced by a Subsystem Instance node.
The components constituting the subsystem should be connected only to the subsystem’s nodes and to themselves.
Input Parameters
This section is used to make a parameterized subsystem. This is an optional feature and enabled only with the Advanced Physics Options checked. It is possible to add required number of parameters by setting Parameters and Default value. These parameters are then available to be used within a subsystem and their actual values are provided by the Subsystem Instance node while linking this subsystem node to the main system.
Context Menus
Lumped Mechanical System > Subsystem Definition
Ribbon
Physics tab with  Lumped Mechanical System selected:
Global > Lumped Mechanical System > Subsystem Definition