Portmon [work] Here

Get the tool from the official Portmon - Sysinternals page.

To understand Portmon’s significance, one must first recall the technical environment of the 1990s and early 2000s. Serial (RS-232) and parallel (Centronics) ports were the primary highways for external devices. Industrial machinery, Point-of-Sale scanners, laboratory instruments, GPS receivers, medical monitors, and early PDAs all spoke over these asynchronous, often finicky, lines. Debugging a communication failure meant guessing: Was the baud rate mismatched? Was there a parity error? Was the device sending a malformed command, or was the software dropping bytes? Traditionally, solving these mysteries required a physical "breakout box" or a hardware logic analyzer—expensive, bulky tools not available to the average developer or technician. portmon

Go to Capture > Ports and check the COM or LPT ports you want to watch. Get the tool from the official Portmon - Sysinternals page

Portmon is a well-known legacy tool from the Windows Sysinternals suite, originally developed by Mark Russinovich. It is designed to monitor and display all serial and parallel port activity on a system. Was the device sending a malformed command, or

: Researchers use Portmon to assess muscular fatigue and recovery times during high-intensity training, such as plyometric exercises.