From owner-freebsd-hardware@FreeBSD.ORG Sat Sep 20 17:01:00 2008 Return-Path: Delivered-To: freebsd-hardware@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id AAFEC106566B; Sat, 20 Sep 2008 17:01:00 +0000 (UTC) (envelope-from freebsd@sopwith.solgatos.com) Received: from parsely.rain.com (parsely.rain.com [199.26.172.196]) by mx1.freebsd.org (Postfix) with ESMTP id 7AD8A8FC19; Sat, 20 Sep 2008 17:00:56 +0000 (UTC) (envelope-from freebsd@sopwith.solgatos.com) Received: from sopwith.solgatos.com (uucp@localhost) by parsely.rain.com (8.11.4/8.11.4) with UUCP id m8KH0ob49501; Sat, 20 Sep 2008 10:00:50 -0700 (PDT) (envelope-from freebsd@sopwith.solgatos.com) Received: from localhost by sopwith.solgatos.com (8.8.8/6.24) id QAA10313; Sat, 20 Sep 2008 16:55:59 GMT Message-Id: <200809201655.QAA10313@sopwith.solgatos.com> To: freebsd-alpha@freebsd.org, freebsd-hardware@freebsd.org In-reply-to: Your message of "Sat, 20 Sep 2008 14:54:14 +0200." <20080920125414.GS93308@cicely7.cicely.de> Date: Sat, 20 Sep 2008 09:55:59 +0100 From: Dieter Cc: 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-hardware@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: General discussion of FreeBSD hardware List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 20 Sep 2008 17:01:00 -0000 [ -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? > 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. :-( 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) Does anyone make firewire to RS-232 bridges?