On Mon, Sep 19, 2022 at 7:51 AM Christo Crause <christo.cra...@gmail.com> wrote:
> > > On Mon, 19 Sep 2022, 03:18 James Richters via fpc-pascal, < > fpc-pascal@lists.freepascal.org> wrote: > >> I can't seem to find any documentation or SerRead or SerReadTimeout.. >> searching for either along with Freepascal doesn't get me any results. >> If it exists somewhere and I am just missing it, can someone tell me where >> it is? >> >> Anyway, what I'm trying to figure out is when the timeout timer starts... >> > > FPC uses the OS provided functionality to interact with the serial port. > On Windows the timeout seems to start when the read request is made ( > https://learn.microsoft.com/en-us/previous-versions/ff547486(v=vs.85)). > On POSIX (at least Linux) it depends on the specific set of flags specified > , scroll down to the discussion on canonical/noncanonical mode for the > details (https://linux.die.net/man/3/termios). > A bit more information after peeking into the source code: on win32 the timeout information can be read or set using Get/SetCommTimeouts. The COMMTIMEOUTS structure ( https://learn.microsoft.com/en-us/windows/win32/api/winbase/ns-winbase-commtimeouts) contains a read interval timeout and total timeouts for read & write operations. SerReadTimeout sets the ReadTotalTimeoutConstant value, so basically the total timeout duration. On Linux SerReadTimeout uses a fpSelect on the handle with the specified timeout, so in principle it is the same behaviour as on Windows, i.e. a total timeout. While both OSs provide some functionality to specify inter character timeouts, FPC does not directly expose this functionality in the Serial unit.
_______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
