Structural Analysis- Dyanmo

Hello everyone,

I have a script that creates simple truss and performs structural analysis by using "structural analysis for dynamo"package. I can easly change the inputs (height, lenght) of structure and perform the analysis after changing them.

When I create custom node from the same script I can still perform analysis but if I change any variable, I need to restart dynamo to perform another analysis.
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I am using same script and I do not understand why this is happening. Is there anyone who can help me about it ?