[PLUG] com port in guest to usb in host (virtual box)

[Neal]

On Sat, Dec 16, 2017 at 9:30 AM, Denis Heidtmann <denis.heidtmann at gmail.com>
wrote:

> With this new found knowledge I noticed that the interface was set for 1
> stop bit.  I set it for two, as the protocol is reported to use.  It made
> no difference in the behavior I observe--no response (other than the usual
> delay) to the request for data.
>

Be aware that if you close and re-open the serial port the driver
might/could/should (I have no experience but something I'd check) reset the
comm parameters. So ideally the program you're talking to the port with
would be the one setting the baud rate and bits so there's no chance for
unintended consequences. I've lost track of how you're doing it.

Ideas?  Should I look for/fabricate connectors which will allow me to use
> my desktop to snoop on the serial traffic?


If you have a couple more serial adapters that would be great, but we
shouldn't have to resort to that. :)


>   Or should I be looking at the
> usb signals?


Only if you have a USB sniffer/protocol analyzer. There's a LOT of stuff
going on at the bus level that would be way too much work to sort out
without one.

Maybe the transmitted signals from the dmm are not getting
> through the usb-serial device.
>

I just recalled a technique used for capturing RF packets from wireless
temperature sensors utilizing the sound card input as a storage scope. If
you're only running 600 baud it will be more than fast enough. All you need
is a resistor or two to scale the input signal:

https://rayshobby.net/reverse-engineer-wireless-temperature-humidity-rain-sensors-part-1/

Enjoy!

NealS