Re: [gentoo-user] Re: serial port identification question

[David Relson]

Hello James,

Thanks for writing.  Lots of good information in your post!

I've working on porting some DOS code to Linux and (as you likely know)
the code needed for serial communications differs greatly between the 2
environments.

The initial problem was trying to identify COM1, COM2, etc from lots
of /dev/tty?? entries.  There were no /dev/ttyS? entries.  This was
solved thru googling and running MAKEDEV (for COM1, COM2, etc).

The second problem seems to be an odd pinout.  The device has an RJ11
connector and came with an RJ11 to RS232 cable.  The DB9 connector is
documented as TX on pin 2 and RX on pin 3 (which is normal).
Connecting a breakout box, indicated TX on pin 3.  With a null-modem
and a loopback plug, send/receive started working using my program.

Send/receive was also verified using 2 terminal sessions and commands:

   cat /dev/ttyS0
   echo this is a test > /dev/ttyS0

The tip on setserial is appreciated.  I learned of stty's -F ... -a
options, but didn't know of setserial.

Having solved/learned the above on the Gentoo box, the next trick is
getting my code to work on the embedded 486SX linux system (non-Gentoo).

So far I know that programmed setting of baud rate is working (as
confirmed with stty).  However no data is being seen  from the keypad
or the two connected preamps.  They should all be continuously sending
data to com3, com2, and com4 (respectively).

The programming world is full of strange and wonderful problems to
solve, isn't it?

Regards,

David