I have working RS-232 serial...

If you are desperate for serial I have what may be a solution, perhaps a little expensive... See this thread:

http://forum.parallels.com/thread8785.html

 

Have you tried unplugging and then replugging the device?

I found that helped to reacquire it after such a shut down.

 

For anyone looking to bridge data transfer between Parallels and an RS-232 device, this "SerialClient" program is a great tool. By connecting to a named socket created by Parallels and passing data through a Keyspan USB to serial adapter, it ensures seamless communication with RS-232 devices. Additionally, the ability to log transferred data for protocol analysis is a valuable feature.

You can download SerialClient from:

Please keep in mind that this software is still in beta, so usual disclaimers apply. Happy testing!