Problem with serial port access

Problem with serial port access

[Lars Bjørndal]

Some random bytes are missing while sending data from DOS to Minicom
over a serial cable. I'd appreciate any help. My setup is as follow:

dosemu-1.4.0 on a Fedora 19 x86_64 system, run by root with -s switch.

setserial /dev/ttyS0
/dev/ttyS0, UART: 16650V2, Port: 0xe030, IRQ: 18

cat /etc/dosemu/dosemu.conf
...
$_com1 = "/dev/ttyS0 irq 18"

(I've also tried without the irq parameter.)

cat /root/.dosemu/drive_c/autoexec.bat
...
Z:\DOSEMU\SYSTEM.COM stty 9600 -F /dev/ttyS0

From DOS, I use

mode com1:96,n,8,1

On another machine, I've setup Minicom with the same parameters, and
started it.

From DOS, I use:

type <file> >com1:

and some bytes are missing from the Minicom output, and the bytes is
different if I run the command once more.

On the machine running DOSEMU, I get the following output with stty -a -F
/dev/ttyS0

speed 9600 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>;
flush = <undef>; min = 1; time = 0;
-parenb -parodd 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

I also has tried to pass crtscts to stty, and then, nothing is sent,
even though I turn on hardware flow control in Minicom.

Minicom to Minicom seems to work properly.

Hope someone can help.

Thanks and regards,
Lars

Re: Problem with serial port access

[John Coppens]

On Sat, 29 Nov 2014 13:58:31 +0100
lars@lamasti.net (Lars Bjørndal) wrote:

> Hope someone can help.

This is somewhat late... and you've probably already solved the 
problem.

Serial port communications is nearly always a headache... I used it for
many years!

Did you check the cable? Does the cable implement the DTR/DSR and/or
CTS/RTS lines (in both directions?) Some cables have strange (and
incorrect) connections at each side.

Some software also uses those lines differently from others. One of
the pairs (DSR/DTR I believe) is software controlled, so they can be
activated at different times.

To avoid cable problems you can try to enable XON/XOFF, and disable
hardware handshaking. This is simpler to debug, and even the simplest
cable should work (3 wires only).

John
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Re: Problem with serial port access

[Lars Bjørndal]

Thank you for your reply. You wrote:

> On Sat, 29 Nov 2014 13:58:31 +0100
> lars@lamasti.net (Lars Bjørndal) wrote:
> 
> > Hope someone can help.
> 
> This is somewhat late... and you've probably already solved the 
> problem.
> 
> Serial port communications is nearly always a headache... I used it for
> many years!
> 
> Did you check the cable? Does the cable implement the DTR/DSR and/or
> CTS/RTS lines (in both directions?) Some cables have strange (and
> incorrect) connections at each side.
> 
> Some software also uses those lines differently from others. One of
> the pairs (DSR/DTR I believe) is software controlled, so they can be
> activated at different times.
> 
> To avoid cable problems you can try to enable XON/XOFF, and disable
> hardware handshaking. This is simpler to debug, and even the simplest
> cable should work (3 wires only).

I don't know anything about the cable. It's connected between two
servers that isn't in house. Actually, the cable workks perfectly when
using screen from one machine to log in to the serial console on
another. After disabeling the serial console, starting dosemu,
using a mode command to setup the port and trying to copy a file
over, it didn't work.

I solved my problem by using other transfere methods.

Again, thank you.

Lars
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