[PLUG] serial communication with dmm (was com port in guest to usb in host (virtual box))

[Denis Heidtmann]

I will make those measurements, but I am doubtful it will show anything.
The schematic I have shows DTR to be the collector and RTS to be the low
end of the emitter resistor of the output NPN.  I did see solid pulses on
the emitter with sigrok.  But perhaps DTR and/or RTS are pulsed when they
should not be.  It is too bad my 'scope has limited record length and no
way to store the data off the 'scope.

On Thu, Dec 28, 2017 at 11:42 PM, Russell Senior <russell at personaltelco.net>
wrote:

> Have you measured the voltages on DTR and RTS during the runs?
>
> Try it with sigrok and with the vendor software and see if there is a
> difference in those values.
>
> On Thu, Dec 28, 2017 at 9:51 PM, Denis Heidtmann
> <denis.heidtmann at gmail.com> wrote:
> > This saga continues.
> >
> > On the laptop with a usb-serial adapter I got to the point where the
> > commands:
> > sigrok-cli --driver mastech-mas345:conn=/dev/ttyUSB0 --show
> > sigrok-cli --driver mastech-mas345:conn=/dev/ttyUSB0 --scan
> > sigrok-cli --driver mastech-mas345:conn=/dev/ttyUSB0 --samples 10
> >
> > behave as expected except the last one returns no data.  I was advised to
> > try using these same commands on the desktop which has an RS232 port,
> thus
> > removing the usb-serial adapter from the picture.  Good idea.
> >
> > After just guessing what serial port to use, I run the following command:
> >
> > sigrok-cli --driver mastech-mas345:conn=/dev/ttyS0 --scan
> > The following devices were found:
> > mastech-mas345 - MASTECH MAS345 with 1 channel: P1
> >
> > This is the same response I got on the laptop.
> >
> > sigrok-cli --driver mastech-mas345:conn=/dev/ttyS0 --show
> > mastech-mas345 - MASTECH MAS345 with 1 channel: P1
> > Supported driver options:
> >     conn
> >     serialcomm
> > Supported configuration options:
> >
> > This is the same response I got on the laptop.
> >
> > sigrok-cli --driver mastech-mas345:conn=/dev/ttyS0 --samples 10
> >
> > [no response except the usual ~10 second delay]
> >
> > This is the same response I got on the laptop.  RATS!
> >
> > This eliminates the usb-serial device from the picture.
> >
> > Recall that when running --samples 10 command on the laptop I was able to
> > detect pulses on the serial line consistent (in a general sense) with a
> > response from the dmm.  Also recall that running  the mfg. sw under
> windows
> > on the desktop showed flawless communication.
> >
> > finally, I report:
> > stty -F /dev/ttyS0 -a   speed 600 baud; rows 0; columns 0; line = 0;
> > intr = <undef>; quit = <undef>; erase = <undef>; kill = <undef>; eof =
> > <undef>;
> > eol = <undef>; eol2 = <undef>; swtch = <undef>; start = <undef>; stop =
> > <undef>;
> > susp = <undef>; rprnt = <undef>; werase = <undef>; lnext = <undef>;
> > discard = <undef>; min = 0; time = 0;
> > -parenb -parodd -cmspar cs7 hupcl cstopb cread clocal -crtscts
> > -ignbrk -brkint ignpar -parmrk -inpck -istrip -inlcr -igncr -icrnl -ixon
> > -ixoff
> > -iuclc -ixany -imaxbel -iutf8
> > -opost -olcuc -ocrnl -onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0
> > vt0 ff0
> > -isig -icanon -iexten -echo -echoe -echok -echonl -noflsh -xcase -tostop
> > -echoprt
> > -echoctl -echoke -flusho -extproc
> >
> > And the protocol is reported to be:
> >
> > data format: 7n2 at 600 baud (7 bits, no parity, 2 stop bits).
> > Control lines:
> >    DTR and RTS lines are used to power the TX line: RTS is clear
> >    for -12 supply; DTR is set for +12 supply. Data transmission is
> >    solicited sending whatever character to the RX line.
> >
> > Any suggestions as to where to go from here?
> >
> > Thanks,
> > -Denis
> > _______________________________________________
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