Ok, folks, Portmon shows COM6 which is the port to a scope, via a USB connection. The terminal program (TeraTerm) is talking to it via that port. Later it's going to be a VBA routine and that's why I need to monitor, to see what gets stuck or doesn't appear.
Long story short I can set Portmon to monitor all other COM ports but not COM6. Says "Portmon cannot attach .... device may be in use". Well, duh, if it weren't in use I wouldn't need to monitor it ;-)
Is that normal? Any remedies? Use another port monitor software? Go back to ye olde logic analyzer like I used to do it (it's heavy, leads to backaches...)?