select bus elements programmatically

Rutherford - 2021-10-07T12:48:43+00:00

Question: select bus elements programmatically

I have signals in a SIMULINK bus and I would like to select specific signals from it. The issue is that I want to run an initialization script that will decide which subset of signals to select. I see that you can select bus signals manually via the bus selector block. Is there any way to perform this function programmatically?  

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Expert Answer

John Michell answered . 2025-12-15

Use set_param on the 'OutputSignals' Parameter

The key parameter for a Bus Selector block is OutputSignals, which specifies the selected elements as a comma-separated string of element names (hierarchical names for nested buses, e.g., 'bus1.signalA,bus2.nestedSignal').

Example Code

Assume your model is loaded, and the Bus Selector block path is 'myModel/mySubsystem/BusSelector1'.

1. Get current selected signals (optional, to build upon existing):

   matlab

    

   currentSignals = get_param('myModel/mySubsystem/BusSelector1', 'OutputSignals');
   disp(currentSignals);  % e.g., 'signal1,signal2,nested.busSignal'

    

    

2. Set new selected signals (overwrites all; specify the full list):

   matlab

    

   set_param('myModel/mySubsystem/BusSelector1', 'OutputSignals', 'signalA,signalB,nestedBus.signalX');

    

    
   • This updates the block: adds/removes output ports accordingly.
   • Element names must match exactly what's available in the input bus (case-sensitive, including hierarchy like 'topBus.subBus.element').
   • For a single element: 'mySignal'
   • For none (clear all): '' (empty string)

3. To add to existing without overwriting:

   matlab

    

   current = get_param('myModel/mySubsystem/BusSelector1', 'OutputSignals');
   newList = [current ',newSignal'];  % Append (add comma if current not empty)
   if ~isempty(current)
       newList = [current ',newSignal'];
   else
       newList = 'newSignal';
   end
   set_param('myModel/mySubsystem/BusSelector1', 'OutputSignals', newList);

    

    

Additional Options

• Output as virtual bus: If you want selected elements grouped into one virtual bus output port:
  matlab

   

  set_param('myModel/mySubsystem/BusSelector1', 'OutputAsBus', 'on');  % or 'off' for separate ports

   

   
• After setting, update the model diagram if needed:
  matlab

   

  set_param('myModel', 'SimulationCommand', 'update');

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