The inport 1 gets the Value from ts_N , defined in the Workspace as a double timeseries Variable.
In the Configuration Parameters which can be accessed by pressing CTRL +E , go to Data Import/Export Category.
The Data Import/Export category includes parameters for configuring input data for simulation (for example, for Inport blocks) and output data (for example, from Outport blocks). The parameters allow you to import input signal and initial state data from a workspace and export output signal and state data to the MATLAB workspace during simulation.
In the Data Import/Export section you can observe that 3 Variables are loaded as inputs to the Model from the Workspace, this is where the inport 1 gets its signal value (ts_N) from.
The Value of ts_N Variable is defined in PreLoadFcn Callback Function which can be viewed and edited by going to the Modeling tab, then clicking Model Settings > Model Properties > PreLoadFcn.
