Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756255Ab0KPSD6 (ORCPT ); Tue, 16 Nov 2010 13:03:58 -0500 Received: from lo.gmane.org ([80.91.229.12]:39821 "EHLO lo.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754620Ab0KPSD5 (ORCPT ); Tue, 16 Nov 2010 13:03:57 -0500 X-Injected-Via-Gmane: http://gmane.org/ To: linux-kernel@vger.kernel.org From: Grant Edwards Subject: Re: [PATCH] Documentation about RS485 serial communications Date: Tue, 16 Nov 2010 18:03:43 +0000 (UTC) Message-ID: References: <20100408111310.524f7354@lxorguk.ukuu.org.uk> <4CBD8EE4.5040808@evidence.eu.com> <201010191727.53314.alexander.stein@systec-electronic.com> <4CC418A9.6090602@evidence.eu.com> <4CDA630F.4060903@atmel.com> <20101110172842.GC12371@suse.de> <4CDBC3EC.6020707@evidence.eu.com> <20101116143016.GB6527@ucw.cz> <20101116172013.102e06a6@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: dsl.comtrol.com User-Agent: slrn/pre0.9.9-102 (Linux) Cc: linux-serial@vger.kernel.org, linux-arm-kernel@lists.infradead.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2107 Lines: 42 On 2010-11-16, Alan Cox wrote: > On Tue, 16 Nov 2010 10:13:22 -0600 > Matt Schulte wrote: > >> On Tue, Nov 16, 2010 at 8:30 AM, Pavel Machek wrote: >> > Hi! >> > >> >> Documentation about RS485 serial communications >> > >> > I have seen hardware (kontron pmc-6l) that was capable of switching >> > between RS232, RS485 and one other standard by software. >> > >> > Is such hw common? If so, should we have standard interface? >> >> In my opinion this type of card is not that common. Generally >> speaking the achievable baud rates for this type of multi-protocol >> card are very limited because of limitations of the transceiver chips. >> It seems that most of the time people would rather have a faster >> serial port than one that does several different voltages > > If there are two types in common use then thats enough to say we should > have a common interface IMHO Comtrol, Moxa, B&B, Sealevel, and others all sell PCI cards and Ethernet attached serial ports that have selectable interfaces (typically RS-232/422/485). Comtrol and Moxa have had drivers in the kernel tree for ages, but they've always had to use custom ioctl calls for things like configuring 232/485/422 mode and half/full-duplex mode. There are also tons of small Linux-based industrial server appliances from Comtrol, Silex, Digi, Moxa, and others that have selectable interface serial ports. Having a standard API for things like interface mode, half-full duplex, inter-character timeout, 9-bit mode, and so on would be life a lot easier for those of us who maintain Linux serial drivers... -- Grant Edwards grant.b.edwards Yow! I always have fun at because I'm out of my gmail.com mind!!! -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/