I'm working on a software development project that requires me to send signals to a device via an RS-232 port. Sadly the included utilities for transferring to and from the device would not work for mass distribution, so I'm left to writing my own. The included documentation doesn't really give any examples of the device's packet structure, and I would like to examine the packets sent to and from their included software package.

Is there a good program that would allow me to monitor packets coming to and from the serial port? Free is preferred, but not required.
['https://superuser.com/questions/101775', 'https://superuser.com', 'https://superuser.com/users/-1/']
[**Portmon**](http://technet.microsoft.com/en-us/sysinternals/bb896644.aspx), from Sysinternals, will do what you need:

> 
> Portmon is a utility that monitors and
>  displays all serial and parallel port
>  activity on a system. It has advanced
>  filtering and search capabilities that
>  make it a powerful tool for exploring
>  the way Windows works, seeing how
>  applications use ports, or tracking
>  down problems in system or application
>  configurations.
> 
> 
> 

![enter image description here](https://i.stack.imgur.com/GCDjb.gif)
<http://www.kmint21.com/serial-port-monitor/> or
<https://iftools.com/start/index.de.php>