From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gerald Emig Subject: Re: RS485 communication Date: Sun, 16 Mar 2003 19:23:31 +0100 Sender: linux-serial-owner@vger.kernel.org Message-ID: <20030316192331.104a4151.gme@emig-software.de> References: <1047598241.5292.2.camel@hp.outpostsentinel.com> <1047732394.20703.10.camel@imladris.demon.co.uk> <1047776160.1327.0.camel@irongate.swansea.linux.org.uk> <1047809131.22070.33.camel@imladris.demon.co.uk> <20030316103517.B14404@flint.arm.linux.org.uk> <1047811906.22070.44.camel@imladris.demon.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from [212.227.126.206] (helo=mrelayng.kundenserver.de) by moutng.kundenserver.de with esmtp (Exim 3.35 #1) id 18ucoN-0007ro-00 for linux-serial@vger.kernel.org; Sun, 16 Mar 2003 19:24:43 +0100 Received: from [217.4.178.231] (helo=emig4.heisch.inka.de) by mrelayng.kundenserver.de with asmtp (Exim 3.35 #1) id 18ucoM-0007Xd-00 for linux-serial@vger.kernel.org; Sun, 16 Mar 2003 19:24:43 +0100 In-Reply-To: <1047811906.22070.44.camel@imladris.demon.co.uk> List-Id: linux-serial@vger.kernel.org To: linux-serial@vger.kernel.org Hi all, RS485 (like RS232-C) is simply an electrical specification, and nothing else. No protocol at all; surely there are "proprietary" ones depending on device manufacturers. If I'm totally wrong please correct me. There are several protocols that use RS485. Samples are Profibus, SIEMENS MPI, ISDN, EIB and many others (maybe even CAN), and they are all different. Most of these protocols use some master - slave conceptuation, but this is not allways necessary; best example for the opposite is good old ethernet. So if we talk about this stuff and keep in mind the goal of the initiator of this discussion, fact is that a protocol must be used when we have more than two devices, either an existing or a new one. Problem: which protocol ??? And it seems to me that this is the real point to be discussed: there is no such protocol (designed for RS485 bus systems) available, right ? Gerald Emig