What are "gap ports" in Simulink?

I am trying to convert a Subsystem to a Subsystem Reference, but I get this error message. What are "gap ports"? I can't find any mention of it on MATLAB Documentation or MATLAB Answers.

Answer 1

[Payas Bahade]

Hi Zachary,

This is a known issue and the error is due to the number of port handles and the number of port blocks inside the Subsystem being unequal.

To get rid of the error, both port handles and port blocks have to be equal in number.

Hope this helps!

[Zachary]

In the end, I was unable find the mismatch between port handles and number of port blocks. Instead of using the toolstrip UI conversion, I manually copied the contents into a new Blank Subsystem, saved the file, and configured a new Subsystem Reference block to point to this new file.

If this post is viewed by others, I might have been able to troubleshoot by reading the block's 'PortHandles' and 'Ports' properties...

port_handles = get_param(gcb,'PortHandles')
ports = get_param(gcb,'Ports')

...and altering the incorrect values with set_param, but I didn't try this so no promises.