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Transport begin

The transport begin represents the first compartment in a transport sub-system, and is “duplicated” when the simulation starts so that the total number of compartments (including the end compartment) equals N. This has the effect that the initial condition of the begin block will be assigned to all compartments of the transport.

The begin block is automatically added when a transport sub-system is created. A transport sub-system can only contain one begin block.

Editing the begin block

NoteMost block properties can be edited directly in the blocks window.

The block editor is shown by right-clicking the block in a window and selecting Edit. In the Blocks window, you can also show the block editor by selecting the block and clicking the Edit button, or by double-clicking the right-most “validation” column of the block.

The block editor has three tabs:


This page lets you edit basic properties such as name, sub-system and base unit. See editing properties for more information.


This page lets you edit the visual properties of the block in the Matrix window. See Editing appearance for more information.


This page lets you specify dimension and index specific properties.

Dimension - You can specify the dimension of the block by using the Type drop down list. Depending on the dimension the index drop down lists are activated. Note that compartments can only be either scalar or vector.

Data - The table let you specify index specific properties like initial conditions. Note that properties assigned here will be used for every compartment in the transfer sub-system.

  • Indices - For blocks that are non-scalar, the first columns will specify indices from the index lists. This allows you to specify different expressions for different indices. The top row is named “default” and can be used when the same value should be set for all indices.
  • Initial Condition - Allows you to enter an expression for the initial inventory of the corresponding material. Note that a value, a parameter or an Expression in the initial condition is evaluated when the simulation is started and time = t0. The Expression editing tool is available to help the user to enter and edit data.
  • dy/dt - Lets you add extra term to the differential equation of the compartment. This feature is useful, for instance, for a simple integration of values where it is not logical to modify the state of the compartment through transfers.
  • Non-negative – If set, the inventory of the compartment cannot be negative. Default = “disabled”
  • Abs. error tol.– Sets the absolute error tolerance for the given material. If empty, the “global” value set in simulation settings is used. Default = <empty>
  • Information - By using the Table control button you can display more columns that will help you document your model.

See also

transport_begin.txt · Last modified: 2019/11/18 13:34 (external edit)