Date: Tue, 05 Feb 2013 11:09:37 -0600 From: Karl Denninger <karl@denninger.net> To: freebsd-stable@freebsd.org Subject: Re: So I whip out a FTDI-based multiport Serial USB Adapter.... [SB QUAR: Tue Feb 5 10:15:47 2013] Message-ID: <51113CD1.40104@denninger.net> In-Reply-To: <CAFYkXj=dSt7hEfGg31ZQdDuqAtM4BKtB-%2Bx5KuZOHGmb_44M=w@mail.gmail.com> References: <511004AA.3060201@denninger.net> <1360008362.93359.485.camel@revolution.hippie.lan> <511020DB.3050302@denninger.net> <1360012382.93359.489.camel@revolution.hippie.lan> <66CBAB45-621B-47F8-AC67-64F816AFE837@bway.net> <1360015226.93359.502.camel@revolution.hippie.lan> <DF3A3AF5-6B74-4D01-9B2E-A1C900540722@bway.net> <51107662.8050708@denninger.net> <51107D82.8040605@denninger.net> <51108DB0.7050403@denninger.net> <bff299b8dda6a83befb45c67ad905944.authenticated@ultimatedns.net> <51113242.4060003@denninger.net> <3af8b2a2d655b0ed501c01e30d00ff0a.authenticated@ultimatedns.net> <CAFYkXj=dSt7hEfGg31ZQdDuqAtM4BKtB-%2Bx5KuZOHGmb_44M=w@mail.gmail.com>
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On 2/5/2013 10:44 AM, CeDeROM wrote: > On Tue, Feb 5, 2013 at 5:27 PM, <chrish@ultimatedns.net> wrote: >> Understood. I was referring to the _computers_ power supply. :) > Still it may be caused by some issued on the USB bus power management. > Normally an USB port can supply 500mA of current. Above that port > should be disabled by the host if I remember correctly. If there is a > hub inside the serial port adapter it would be good to know it it is > powered directly from the USB port or does it have its own power > supply... > > There could be too much power drain from the USB port by external > devices attached to the hub/adapter. But this would be rather obvious. > > There may be some misunderstanding between USB Host and the self > powered USB device, so they cannot agree on the power supply level, > which seems more probable :-) The FTDI adapter has the provision for an external power supply (+5V) but it does not require it unless you're running off an unpowered bus, which is not normally the case. 500ma is quite a bit of available energy. I suspect the issue is found in the KVM, which attaches as a "low" speed device; I'm going to see if I have the same issue with other USB devices connected while the KVM is on the box. -- -- Karl Denninger /The Market Ticker ®/ <http://market-ticker.org>; Cuda Systems LLC
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