Hello, I want to use (Windows-) COM port numbers greater than 16, but when I use open() to get a file descriptor for the devices I get the behaviour:
---1.case----------------------------------------- errno = 0; fd = open("/dev/com8", O_RDWR | O_NONBLOCK); -> fd = 3, errno = 0 -> everything is OK, I can use the opened COM port ---2.case----------------------------------------- errno = 0; fd = open("\\.\com8", O_RDWR | O_NONBLOCK); -> fd = 3, errno = 20 = ERROR_BAD_UNIT = "The system cannot find the device specified" -> I can not use the opened COM port. The port number 1...16 versus 17...255 does NOT matter. ---3.case----------------------------------------- errno = 0; fd = open("/dev/com23", O_RDWR | O_NONBLOCK); -> fd = -1, errno = 2 = ERROR_FILE_NOT_FOUND = "The system cannot find the file specified" -> I can not use the opened COM port. The port number 1...16 (OK) 17...255 (not OK) DOES matter. ---end cases------------------------------------ Is there a workaround? Lutz Hoerl Thorlabs GmbH Gauss-Strasse 11 D-85757 Karlsfeld Germany Tel. +49 (0)8131 5956 44 FAX +49 (0)8131 5956 99 M A I L lhoerl at thorlabs dot com -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/