Date: Sat, 20 Sep 2008 09:55:59 +0100 From: Dieter <freebsd@sopwith.solgatos.com> To: 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. Message-ID: <200809201655.QAA10313@sopwith.solgatos.com> In-Reply-To: Your message of "Sat, 20 Sep 2008 14:54:14 %2B0200." <20080920125414.GS93308@cicely7.cicely.de>
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[ -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?
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