To step back a bit I fabricated a little fixture to make it convenient to test the lines going into the dmm. I found a description of those lines: 5-pin inline connector.
pin 1 Gnd pin 2 TX pin 3 RTS (must be off) pin 4 DTR (must be on) pin 5 RX The connections are through optical couplers in the meter, hence the "must be" conditions. Pin 2 connects to the anode of the led of the input coupler, pin 3 is connected to the emitter of the output npn through a resistor, pin 4 connects to the collector of the output npn, and pin 5 connects directly to the emitter of that npn. I ran (what I presume is the vendor's sw) in a VB windows 2000 guest on my desktop (Lenovo ThinkCentre M92P), which has an RS232 port. The sw communicates with the dmm fine. I checked the voltages wrt Gnd: Pin 2 -10 (the meter I used did not detect the signal - I need to use a 'scope to see what the signal actually is) pin 3 -9.5 to -10 pin 4 +10 to +10.8 on line; -10V off line. pin 5 data When I was examining this with the laptop and the usb-to-serial adapter I saw voltages no higher than 6.4V. It is possible that explains the lack of response from the meter, although the sigrok --scan and --show commands did find the meter. I do not know how the meter could be identified without valid communication. So this is the status. I will check the voltages when connected to the laptop, and drag out the 'scope to see what I can learn. On Mon, Dec 11, 2017 at 12:28 PM, Russell Senior <[email protected]> wrote: > On Mon, Dec 11, 2017 at 11:21 AM, Denis Heidtmann > <[email protected]> wrote: > > Is it possible that your command /dev/ttyUSB0 600,cs7,cstopb,-parenb has > an > > error? > > Not only possible, but likely. > > > I executed stty 600 then stty -a : > > denis@denis-ThinkPad-L420:~$ stty -a > > speed 600 baud; rows 24; columns 80; line = 0; > > intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>; > > eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt > = > > ^R; > > werase = ^W; lnext = ^V; discard = ^O; min = 1; time = 0; > > -parenb -parodd -cmspar cs8 -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 > > > > Then I tried stty cs7 and got: > > denis@denis-ThinkPad-L420:~$ stty cs7 > > stty: 'standard input': Invalid argument > > > > Yet the man page lists csN. > > > > Clearly I do not know what I am doing. > > You probably need to tell it which tty you want to talk to, otherwise > it will try to set your current terminal, afaik. > > The device-busy thing may be due to a screen session still running. > Try unplugging/replugging your cable from the USB port. > _______________________________________________ > PLUG mailing list > [email protected] > http://lists.pdxlinux.org/mailman/listinfo/plug > _______________________________________________ PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
