Re: Serial port read working but not write.

[Jan-Benedict Glaw <jbglaw@lug-owl.de>]

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On Fri, 2004-07-23 11:30:11 +0200, Salomon, Frank <frank.salomon@wincor-nixdorf.com>
wrote in message <4100DAA3.7060205@wincor-nixdorf.com>:
> Hi,
> the problem is you need a procedure which find out what the problem is.
> Hardware check:
> Your hole hardware you can divided in:
> - PC - com port
> - cable
> - external Hardware
> 
> Check the com-port:
> create a cable bridge between pin 2 and 3 of you port.
> run # dd bs=1 count=1 if=/dev/ttySx | hexdump
> on an other vt run # cat /dev/inittab > /dev/ttySx
> 
> If you don't see any output on the vt, which is running "dd bs=1 count=1 
> if=/dev/ttySx | hexdump", your com port is not working correct.

This doesn't need to work, depending on handshake settings. Also, (at
least in theory), you can have different sending and receiving speeds...

> Next you can connect your cable to the PC and pug the bridge to the
> end of the cable and perform the same test.

...which also depends on tty settings.

man stty

MfG, JBG

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