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

[Galen Seitz]

On 12/14/17 21:24, Denis Heidtmann wrote:
> Measuring with a 'scope with the laptop issuing the  command sigrok-cli
> --driver mastech-mas345:conn=/dev/ttyUSB0 --samples 10:
> 
> triggering on DTR
> 
> DTR goes from -6.6V to +7.6V and remains there 'till 9.64s
> RX goes from -2.6V to +6.4V for .48s then again at 2.6s,3.12s, etc 'till
> 7.32s (10 groups of data pulses after the initial .48s wide group)
> RTS sits at -6.4V except for a narrow spike to +6.6V at 2.44s
> TX  starts at -6.4V 'till 2.6s, 3.12s, etc where it has a double pulse of
> 5ms each spaced 1.7ms. These pulse groups start synchronously with the RX
> groups.
> 
> If I want to get more detail I think I need to trigger on TX.
> 
> So it looks like data is being sent. Is it received and sent to a bit
> bucket, or not received by the usb-to-serial device?  How to find out?

I think you should first confirm the baud rate.  Put your scope on the
RX line (assuming that's the output from the DMM) and look for the
narrowest positive or negative pulse.  That pulse width should tell you
what baud rate the DMM is using.  Confirm that you have configured the
serial port correctly.

Do you have a digital scope?  If not, I can see how you might have
trouble capturing these single shot events.  I could probably make it to
the clinic on Sunday if you'd like some help with this.

galen
-- 
Galen Seitz
galens at seitzassoc.com