A curious question - is it possible on a 16FX target to detect a connected debugger at runtime ?
I checked hardware manual (Cypress MB96300 Series Hardware Manual, Doc. No. 002-19737 Rev.), especially everything related to the EDSU, but no such thing was mentioned.
The ETM peripherals on Cortex M MCUs usually allows such a feature.
Background is, I consider using the USART interface reserved for the debug connection to output runtime logging messages if no debugger is connected. I am sure an attached debugger will not cope well with such a feature, probably breaking the connection.