https://rs-232-monitor.software.informer.com/
RS-232 Monitor (RSMon.exe). RS-232 monitor allows to communicate with devices connected to serial port by rs232 protocol.
serial portrsmonitordownload
https://www.eltima.com/com-port-data-emulator/
Find out how to emulate COM port activity of serial devices with Serial Port Monitor acting as a COM port data emulator
com portserial monitordataemulator