MATLAB: How to have the From Workspace block output the data at a certain time step in Simulink 6.5 (R2006b)

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I have a From Workspace block and I want this block to output the signal at a certain time step and not immediately after starting the simulation.

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The Triggered Signal From Workspace block in the Signal Operations library of the Signal Processing Blockset 6.4 (R2006b) can be used to import signal samples from the MATLAB workspace into the Simulink model at a certain time when triggered by the control signal at the input port.

You can also use the following approach to output a signal from workspace at a certain time step:

- use a Lookup Table block instead of the From Workspace block

- enter the time and signal values into the "Vector of input values" and "Table data" fields of the Lookup Table

- create a simple counter based on Sum block and feedback loop to feed the Lookup Table

- place all in an enabled subsystem

Now you should be able to output the signal from workspace when you enable the subsystem. Refer to the attached model example.mdl for more information.

You can also mask the subsystem to provide time and signal data as mask parameters. If you want to be able to output a signal from a mat-file at a certain time step, you can create a even more complex mask. This mask would take the mat-file's name as a parameter and could then load the mat-file's data in the mask initialization function. Note that you might need to properly set parameters like the sample times if you want to use this approach.

Related Solutions

MATLAB: How to vary the values of the Analog Output signals during real-time simulation on the target in xPC Target 2.7.2 (R14SP2)

This can be done in xPC Target 2.7.2 (R14SP2) by using a Look-Up Table block. The attached model, lookupex.mdl, provides a simple example of this. The Lookup Tables are fed by constant blocks. If you build this model and enter the command:

set(tg,'ShowParameters','on');

you will see the following tunable parameters:

 Parameters           = INDEX   VALUE             TYPE      SIZE    PARAMETER NAME                BLOCK NAME                    
                           0       [...]             DOUBLE    1*10    Value                         Constant                      
                           1       [...]             DOUBLE    1*10    Value                         Constant1                     
                           2       [...]             DOUBLE    1*10    InputValues                   Lookup Table                  
                           3       [...]             DOUBLE    10*1    OutputValues                  Lookup Table                  
                           4       [...]             DOUBLE    1*10    InputValues                   Lookup Table1                 
                           5       [...]             DOUBLE    10*1    OutputValues                  Lookup Table1

Therefore, you can completely specify vectors for the Analog Output using the values for the Constant blocks and the the Output Values in the Lookup Tables with the SETPARAM function as follows:

setparam(tg,3,rand(1,10));

Match up the first input value with the Output Value you would like for the first element of the vector, and so on. You could do this independent of Analog Input values, or any other values for that matter. You can also set the sample times based on the length of time you want the signals to be output.

MATLAB: How to add or remove specific S-function block ports in Simulink 6.5 (R2006b)

The ability to add or remove specific S-function block ports is not available in Simulink 6.5 (R2006b).

To work around this issue, you can put your S-function block inside a masked Subsystem block. This creates another hierarchical layer for your S-function block, such that it connects to the rest of the model through the Subsystem block's inports and outports. Within the context of that Subsystem, you can use a mask callback function to implement logic that allows the block to maintain its wiring. For example, use the:

1. ADD_LINE and DELETE_LINE functions to create and remove signal lines

2. SET_PARAM function to change the port number of a specific port

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Related Solutions

MATLAB: How to vary the values of the Analog Output signals during real-time simulation on the target in xPC Target 2.7.2 (R14SP2)

MATLAB: How to add or remove specific S-function block ports in Simulink 6.5 (R2006b)

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