COM port not visible when connected to the my circuit

Hardware Development
1

Hi, I am using a Daisy Seed and protoboards to add an SD and MIDI interface. I programmed the Daisy to send messages via COM-port to the PC

Sometimes the COM port is invisible when turning ON the Daisy when it is in the protoboard. This does not happen when the daisy is not connected to anything

I am using this circuit, similar to Daisy Pod
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2

That MIDI interface is all wrong, and not similar to Daisy Pod. The purpose of the optoisolator is to completely isolate the two devices. I don’t know if this is causing your problem, but it is not correct.

This is the MIDI IN on Daisy Pod:

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