From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4B582E1F.9050505@domain.hid> Date: Thu, 21 Jan 2010 11:36:15 +0100 From: Alexandre Coffignal MIME-Version: 1.0 References: <4B57134A.3090702@domain.hid> <4B5816E7.2080108@domain.hid> <4B58233A.4070708@domain.hid> <4B582AC4.5030104@domain.hid> In-Reply-To: <4B582AC4.5030104@domain.hid> Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Subject: Re: [Xenomai-core] [PATCH] assert RTS signal during transmit in EIA-485 half duplex mode for 16550A compatible controllers. List-Id: Xenomai life and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: "xenomai@xenomai.org" Jan Kiszka a =E9crit : > Alexandre Coffignal wrote: > =20 >> Hello, >> >> Thanks you for your response. >> >> I used this patch to communicate with a slave equipment in rs485 (modbus >> protocol). The data is transmitted over a 2-wire twisted pair bus. >> Master initiates all communication activity, by sending data. To do this >> it must set RTS line to high state during all it's transmission. Before >> slave answer, master must lower the RTS line. >> =20 > > Will the slave wait on the deassertion of RTS? Or what will happen if > RTS is still high and the slave starts its answer? > > =20 No slave does not wait on the deassertion of RTS, if RTS is still high during slave answer, it happen a collision and=20 the master does not receive the frame. > =20 >> my slave equipment answer in less than 200us, so i must know when xmit >> is completing to lower the RTS line >> >> An extension to RTSER_RTIOC_WAIT_EVENT may be a good solution but do you >> know if an extension to RTSER_RTIOC_WAIT_EVENT can guarantee this timing? >> >> =20 > > Given a proper platform (check its capabilities with the latency or the > irqbench test), yes. It's a myth that such things can only be done in > kernel space. > > Jan > > =20 Ok I take note of this, but do you think this function should not be in kernel space in half duplex RS485 ? --=20 Alexandre COFFIGNAL, Chef de Projet Email: alexandre.coffignal@domain.hid ------------------------------------ C=E9noSYS 10, Rue Xavier Bichat F-72000 Le MANS Tel: +33(0) 243 511 797 web : http://www.cenosys.com ------------------------------------ CONFIDENTIALITE : Ce message =E9lectronique et tous les fichiers attach=E9s qu'il contient sont confidentiels et destin=E9s exclusivement =E0 l'usage de la personne =E0 laquelle ils sont adress=E9s. Si vous avez re=E7u ce message par erreur, merci de le retourner imm=E9diatement a son =E9metteur sans en conserver de copie. CONFIDENTIALITY : This e-mail and any attachments are confidential and may also be privileged. If you are not the named recipient, please notify the sender immediately and do not disclose the contents to an other person, use it for any purpose, or store or copy the information in any medium.