From owner-freebsd-usb@FreeBSD.ORG Sat Oct 4 21:30:56 2008 Return-Path: Delivered-To: freebsd-usb@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 930411065693; Sat, 4 Oct 2008 21:30:56 +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 DECEE8FC17; Sat, 4 Oct 2008 21:30:55 +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 m94LUnS90782; Sat, 4 Oct 2008 14:30:49 -0700 (PDT) (envelope-from freebsd@sopwith.solgatos.com) Received: from localhost by sopwith.solgatos.com (8.8.8/6.24) id VAA24823; Sat, 4 Oct 2008 21:29:08 GMT Message-Id: <200810042129.VAA24823@sopwith.solgatos.com> To: freebsd-usb@freebsd.org, freebsd-alpha@freebsd.org, freebsd-hardware@freebsd.org In-reply-to: Your message of "Thu, 25 Sep 2008 21:00:22 +0200." <20080925190022.GB93308@cicely7.cicely.de> Date: Sat, 04 Oct 2008 14:29:08 +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-usb@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: FreeBSD support for USB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 04 Oct 2008 21:30:56 -0000 > > Surely a "good" USB to RS-232 bridge (if one exists?) or a RS-232 > > filter/isolator (assuming they exist?) would be *far* less expensive > > than the server class alpha you suggest below. > > It depend on how much RS232 you need and how many slots the OP has free. > Nevertheless a "good" RS232 bridge if needed in number are not cheap > either - ntoe that you can get affordable PCI extenders as well. The PCI expanders I've seen cost almost as much as getting an entire additional machine. > > > > The problem with PCI is the limited number of slots. :-( > > > > > > Well - not realy with server class alphas... > > > > In my world, a "server" means 1-4 full height 19" racks with quite large > > price tags and power&cooling requirements. Some people think a server > > is a pee-cee. So I'm not sure what you mean by "server class alphas". > > Server doesn't mean rack, but beside from a few OEM boards and small > 19" system all alphas have lots of free slots available. > > > I have what I would call a "workstation" class alpha, which cost an > > obscene amount to get 6 PCI slots instead of 4, and at times they are > > all full. So I can't use up a slot just to get a couple more RS-232 > > ports. How many PCI slots does a server class alpha have? > > Well the AS4100 I have already has 8 slots which is not that uncommon > for alpha servers. I'd call an alpha with only 8 slots a workstation class machine. It wouldn't take much to fill up 8 slots. > The real big ones can even have a few hundred slots. A few hundred slots would be server class. And I'm sure a price tag to match, along with floor space, power, and cooling requirements. > > USB to RS-232 bridge could be a good solution, if I knew which > > make&model of bridge worked well with *BSD. Poking around on the web > > I can't even find what chip they have inside. > > Really forget about USB to RS232. > It is not the chip which is the problem it is the principal. > You really need galvanic isolation, because USB can't handle ground > loops, which no cheap device has. > You can use any kind of chip with propper isolation, but then it > is likely more expensive than any other kind of solution. I assume this is marketing driven. Adding a few optos can't increase the manufacturing cost *that* much. Sounds like a market opportunity for someone. > > Do these bridges actually work properly, or do they have gotchas > > like the USB to SATA/PATA bridges? > > The prolific bridges work well enough if you don't have a ground > loop and FTDI chips are better IMHO. Thanks.