{"id":17147,"date":"2024-09-19T15:56:16","date_gmt":"2024-09-19T19:56:16","guid":{"rendered":"https:\/\/blogs.mathworks.com\/simulink\/?p=17147"},"modified":"2024-09-19T15:56:16","modified_gmt":"2024-09-19T19:56:16","slug":"how-to-correct-errors-in-port-width-or-dimension-in-simulink","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/simulink\/2024\/09\/19\/how-to-correct-errors-in-port-width-or-dimension-in-simulink\/","title":{"rendered":"How to correct errors in port width or dimension in Simulink?"},"content":{"rendered":"
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Let's continue our tour of the most viewed Simulink-related MATLAB Answers. This week, we look at:<\/span><\/div>
How to correct error in port width or dimension in simulink ?<\/span><\/a><\/div>
While this error mentions dimensions, the same principles and techniques to debug this error apply also to other properties like data types and sample times.<\/span><\/div>

The Problem<\/span><\/h2>
To begin, let's recreate a model similar to the one in the <\/span>MATLAB Answers post<\/span><\/a>:<\/span><\/div>
\"\"<\/img><\/div>
mdl = <\/span>\"PropagationIssue\"<\/span>;<\/span><\/span><\/div><\/div>
out = sim(mdl,<\/span>\"CaptureErrors\"<\/span>,<\/span>\"on\"<\/span>);<\/span><\/span><\/div><\/div>
out.ErrorMessage<\/span><\/span><\/div>
ans = <\/span><\/div>
'Error due to multiple causes.\r\n Caused by:\r\n Invalid setting for input port dimensions of 'PropagationIssue\/Demux'. The dimensions are being set to [-1]. This is not valid because the total number of input and output elements are not the same\r\n Error in port widths or dimensions. Invalid dimension has been specified for 'Output Port 1' of 'PropagationIssue\/Transfer Fcn'.'\r\n<\/div><\/div><\/div><\/div><\/div><\/div>

A First Solution<\/span><\/h2>
In this specific model, my best guess is that the user thought that they had to use a <\/span>Demux<\/span><\/a> block to send a signal to two destinations. The simplest way to fix this model is to get rid of the Demux block and simply branch the signal. To branch a signal, you can right-click on it and drag.<\/span><\/div>
\"RemoveDemux.gif\"<\/img><\/div>
While this model is easy to fix, getting this error in a more complex model can be challenging. Let's see how I typically debug this error.<\/span><\/div>

Debugging Tips<\/span><\/h2>
When running into propagation errors, there are typically two blocks reported: The source and the destination. In this case we have:<\/span><\/div>