- pyformat 1.1.2 by bjo OK, I have 'forced into it'. Here it goes. I have just used untested code to reply to this listserv. I have never been able to just send out evaluation-only hardware that had not had at least had a pre-scan for EMC conformity, no matter how simplistic the circuit So what is the basis of the statement "Software System Safety is probably more of a black art than EMC/EMI" ? You tell me. Did the untested code work ??
The minions will now descend upon thine head to smite my impudence, not to hear me sayeth thine shall never forsake the glory of the code verification and validation. Brian > -----Original Message----- > From: [email protected] [mailto:[email protected] <mailto:[email protected]> ]On Behalf > Of Oscar Overton > Sent: Wednesday, February 10, 2010 5:52 AM > To: [email protected]; [email protected] > Subject: Re: [PSES] Agency Probes Gas Pedals' Link to EMI > > The problem with interconnecting systems is that the > complexity increases. > The last thing you need in a software driven system is added > complexity. > Software System Safety is probably more of a black art than > EMC/EMI, and > just as susceptible to system changes. > Additionally, the interface between hardware and software is > a critical > one. > > Redundancy still leaves potential problems if the systems > are not also > independent. > > Even with simple analog electrical circuits the > interconnecting of systems > leads to "sneak circuits", and unintended operations. > These sneak circuits can also manifest themselves in software. > > A good starting point is the following reference: Software > System Safety > Handbook > > http://www.system-safety.org/Documents/Software_System_Safety <http://www.system-safety.org/Documents/Software_System_Safety> > _Handbook.pdf > > > A good article highlighting the impact of complexity: > Software Safety and > Rocket Science > > http://ercim-news.ercim.eu/content/view/473/687/ <http://ercim-news.ercim.eu/content/view/473/687/> > > This page has several other links related to this topic. > > Oscar Overton > Product Safety > Lexmark International, Inc. > Phone: 859-232-2284 > Email: [email protected] > > Ralph.McDiarmid@c > > a.schneider-elect > > ric.com > To > Sent by: > [email protected] > [email protected] > cc > Subject > 02/08/2010 01:56 Re: [PSES] Agency > Probes Gas > PM Pedals' Link to EMI > > It might be wise to design a circuit which over-rides the accelerator > whenever the brake pedal is depressed. ?That over-ride > circuit could be > made fault tolerant through redundancy, but at some level of > disturbance no > electronic circuit is likely to be fault-tolerant. > > Mechanically linked throttles were also known to stick, > sometimes due to > weather. ? ?I wonder if the failure rates of those are > comparable to the > electronic versions. > > Ralph McDiarmid ?| ? Schneider Electric ? | ?Renewable > Energies Business > | ? CANADA ?| > > From: John Woodgate <[email protected]> > To: [email protected] > Date: 02/06/2010 02:55 AM > Subject: Re: [PSES] Agency Probes Gas Pedals' > Link to EMI > > In message <c7927e83.658c2%[email protected]>, dated Sat, 6 > Feb 2010, Ken Javor <[email protected]> writes: > > >But that's like saying, yes it is possible that it will > rain in Death > >Valley, when inquiring if damage to a domicile might have > been caused > >by a hurricane. > > I was pointing out that the question demanded such a response and was > therefore not the right question. > > > >The real question, given present automotive EMI standards, > is "What is > >the probability that a real world threat exceeded the stress levels > >imposed during radiated susceptibility qualification (which runs 100 > >V/m or higher to my knowledge)?" > > Yes, that's close enough to the right question. > > I'm not familiar with the European requirements, which are > embodied in > the Automotive Directive, not in standards. But I understand > that they > are very stringent. A few significant problems were > experienced prior to > the Directive, some involving rural roads exposed to very > high RF field > strengths from nearby broadcast transmitters. > > Nevertheless, no amount of testing, however stringent and > well-implemented, can foresee all possibilities, because the > micro-environment in the vehicle can be affected by the owner. For > example, a metal box without a lid might act as a resonant cavity and > produce a local highly-intensified field strength close to an > electronics box hidden behind a side panel of the vehicle interior. > -- > OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk > John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]>
