Primary goals of this monograph:

While Sscom is a champion in its own right, it's helpful to see how it stacks up against other popular serial debuggers.

Serial Debug Assistant - Free download and install on Windows

For cellular modems (GSM/GPRS/LTE) or Bluetooth modules, you can load a list of sequential AT commands into the multi-string panel: AT (Check status) AT+CSQ (Check signal quality) AT+CREG? (Check network registration)