From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4FE6F7C4.7030500@tudelft.nl> Date: Sun, 24 Jun 2012 13:19:32 +0200 From: Uwe Fechner MIME-Version: 1.0 References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai] a question:deadline for the real devices List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: xenomai@xenomai.org Hi, for realtime I/O you need drivers that support Xenomai. They are available for serial I/O, CAN bus, Ethercat and probably more. Avoid USB (not as realiable as needed for industrial applications). With respect to disc I/O: First of all use an SSD harddisc that has a RAM input cache. Than you could also create a thread that receives data via a realtime queue and writes it with a lower priority the hard disc. I am not sure if this is always needed. Best regards: Uwe Fechner On 24.06.2012 12:59, ali hagigat wrote: > When we talk about Xenomai and a hard real time system, every thing > seems OK regarding to tasks and the CPU code, what about the > functionality of I/O devices? > > Like there is no guarantee for writing a sector on a hard disk below a > specified time. Or reading/writing a USB device. > > I mean doing a real input/output action seems not to have a specific > deadline. While sometimes it seems we need to have it. > > Any comment and direction will be appreciated much. > > _______________________________________________ > Xenomai mailing list > Xenomai@xenomai.org > http://www.xenomai.org/mailman/listinfo/xenomai -- ---------------------------------------- Uwe Fechner, M.Sc. Delft University of Technology Faculty of Aerospace Engineering/ASSET Kluyverweg 1, 2629 HS Delft, The Netherlands Phone: +31-15-27-88902