From owner-freebsd-alpha@FreeBSD.ORG Thu Sep 25 12:54:31 2008 Return-Path: Delivered-To: freebsd-alpha@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 419061065694 for ; Thu, 25 Sep 2008 12:54:31 +0000 (UTC) (envelope-from ticso@cicely7.cicely.de) Received: from raven.bwct.de (raven.bwct.de [85.159.14.73]) by mx1.freebsd.org (Postfix) with ESMTP id BFB2C8FC1B for ; Thu, 25 Sep 2008 12:54:30 +0000 (UTC) (envelope-from ticso@cicely7.cicely.de) Received: from cicely5.cicely.de ([10.1.1.7]) by raven.bwct.de (8.13.4/8.13.4) with ESMTP id m8PCsNaA027385 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Thu, 25 Sep 2008 14:54:24 +0200 (CEST) (envelope-from ticso@cicely7.cicely.de) Received: from cicely7.cicely.de (cicely7.cicely.de [10.1.1.9]) by cicely5.cicely.de (8.14.2/8.14.2) with ESMTP id m8PCsJlK031190 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 25 Sep 2008 14:54:21 +0200 (CEST) (envelope-from ticso@cicely7.cicely.de) Received: from cicely7.cicely.de (localhost [127.0.0.1]) by cicely7.cicely.de (8.14.2/8.14.2) with ESMTP id m8PCsJPC060059; Thu, 25 Sep 2008 14:54:19 +0200 (CEST) (envelope-from ticso@cicely7.cicely.de) Received: (from ticso@localhost) by cicely7.cicely.de (8.14.2/8.14.2/Submit) id m8PCsH3Q060058; Thu, 25 Sep 2008 14:54:17 +0200 (CEST) (envelope-from ticso) Date: Thu, 25 Sep 2008 14:54:17 +0200 From: Bernd Walter To: Dieter Message-ID: <20080925125417.GQ93308@cicely7.cicely.de> References: <20080920125414.GS93308@cicely7.cicely.de> <200809201655.QAA10313@sopwith.solgatos.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200809201655.QAA10313@sopwith.solgatos.com> X-Operating-System: FreeBSD cicely7.cicely.de 7.0-STABLE i386 User-Agent: Mutt/1.5.11 X-Spam-Status: No, score=-4.3 required=5.0 tests=ALL_TRUSTED=-1.8, AWL=0.064, BAYES_00=-2.599 autolearn=ham version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on spamd.cicely.de Cc: freebsd-alpha@freebsd.org, freebsd-hardware@freebsd.org Subject: Re: alpha/127248: System crashes when many (7) serial port terminals (vt320-vt510) connected to the server via com to usb adapter and 2-usb hubs. X-BeenThere: freebsd-alpha@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: ticso@cicely.de List-Id: Porting FreeBSD to the Alpha List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 25 Sep 2008 12:54:31 -0000 On Sat, Sep 20, 2008 at 09:55:59AM +0100, Dieter wrote: > [ -hardware@ list added to existing -alpha@ thread as this > doesn't seem to be alpha specific ] > > > This is because USB is absolutely crap for this purpose. > > RS232 terminals, especially with long cables, can produce several kind > > of spikes and ground loops, which USB is very very sensitive about. > > Many things about USB are crap (thanks, inthell), but if a USB to RS-232 > bridge cannot handle normal spikes and ground loops, I'd blame the > bridge, not USB itself. If the problem is spikes and ground loops > there is probably some RS-232 filter/isolator available to clean them > up. There could be a bug in the bridge which needs a software workaround. > In any case the system shouldn't crash. > > Are there specific make&model USB to RS-232 bridges that people > have had good luck with? USB can't handle spikes and ground loops. As said: use isolated devices, so you don't have the loops and spikes. You can blame the device for not being isolated, but you expect every device to provide expensive workaround for a design failure. USB is designed for cheap stuff - that's all about it. Yes - the system shouldn't crash, but don't expect it ever being fixed for FreeBSD-alpha. > > My advise is to use a completely other technology to connect the terminals. > > A galvanic isolated USB device might work, but there are lot of PCI and > > Ethernet devices on the market which are more solid by design than USB. > > The problem with PCI is the limited number of slots. :-( Well - not realy with server class alphas... > Ethernet could be a good solution for some applications, if you > can get the software to deal with it. NFS is crap, *real* distributed > file systems handled devices transparently. (thanks, Sun) This is a different topic. For RS232 Ethernet is quite reasonable. > Does anyone make firewire to RS-232 bridges? Or stay with the old DEC devices - they are rock solid even after all those years. -- B.Walter http://www.bwct.de Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.