Re: open () and /dev/ttyS0

[Craig Gullixson <craig at nso dot edu>]

It turns out that the permission denied error was due to a typeo causing
an attempt to open the serial port a second time (me: bashing head against
wall).  After that was corrected, tty port works fine with my POSIX tty
library.

---Craig

>
>I have an application where I need to communicate with some simple
>controllers via serial commands.  I have a package to do the low level
>open,read,write, and close tasks for a tty port that I have been using
>for a number of years under Solaris using the standard POSIX tty calls.
>
>My problem is that when attempting to open /dev/ttyS0, I get a
>permission denied error.  I get the same error when attempting to
>open /dev/com1.  Curiously, the open works when opening "com1" but
>the tcgetattr () call then fails with a not a typewriter error
>(presumably ENOTTY).
>
>I can manually communicate with the controllers via hyperterm.
>
>My configuration is 
>
>uname -a output:
>
>CYGWIN_NT-5.0 dlsppc 1.5.5(0.94/3/2) 2003-09-20 16:31 i686 unknown unknown 
>Cygwin
>
>The windows system is:
>
>Windows 2000 Professional Ver 5.0 Build 2195 Service Pack 4
>
>built on a FAT32 partition.
>
>
>I have noted several similar problems with opening serial ports in the
>archives but have not see anything regarding this being resolved.
>
>Any suggestions would be appreciated.
>
>---Craig
>
>
>________________________________________________________________________
>Craig A. Gullixson
>Instrument Engineer			INTERNET: cgullixson@nso.edu
>National Solar Observatory/Sac. Peak    PHONE: (505) 434-7065
>Sunspot, NM 88349 USA                   FAX: (505) 434-7029
>


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