Path: ...!weretis.net!feeder9.news.weretis.net!i2pn.org!i2pn2.org!.POSTED!not-for-mail From: George Neuner Newsgroups: comp.arch.embedded Subject: Re: Diagnostics Date: Fri, 18 Oct 2024 17:42:44 -0400 Organization: i2pn2 (i2pn.org) Message-ID: <77k5hjprfq0ipjp6pcdd03lnph1i76ssuu@4ax.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Injection-Info: i2pn2.org; logging-data="2648522"; mail-complaints-to="usenet@i2pn2.org"; posting-account="h5eMH71iFfocGZucc+SnA0y5I+72/ecoTCcIjMd3Uww"; User-Agent: ForteAgent/8.00.32.1272 X-Spam-Checker-Version: SpamAssassin 4.0.0 Bytes: 3267 Lines: 53 On Fri, 18 Oct 2024 20:30:06 -0000 (UTC), antispam@fricas.org (Waldek Hebisch) wrote: >Don Y wrote: >> Typically, one performs some limited "confidence tests" >> at POST to catch gross failures. As this activity is >> "in series" with normal operation, it tends to be brief >> and not very thorough. >> >> Many products offer a BIST capability that the user can invoke >> for more thorough testing. This allows the user to decide >> when he can afford to live without the normal functioning of the >> device. >> >> And, if you are a "robust" designer, you often include invariants >> that verify hardware operations (esp to I/Os) are actually doing >> what they should -- e.g., verifying battery voltage increases >> when you activate the charging circuit, loopbacks on DIOs, etc. >> >> But, for 24/7/365 boxes, POST is a "once-in-a-lifetime" activity. >> And, BIST might not always be convenient (as well as requiring the >> user's consent and participation). >> >> There, runtime diagnostics are the only alternative for hardware >> revalidation, PFA and diagnostics. >> >> How commonly are such mechanisms implemented? And, how thoroughly? > >This is strange question. AFAIK automatically run diagnostics/checks >are part of safety regulations. Even if some safety critical software >does not contain them, nobody is going to admit violationg regulations. >And things like PLC-s are "dual use", they may be used in non-safety >role, but vendors claim compliance to safety standards. However, only a minor percentage of all devices must comply with such safety regulations. As I understand it, Don is working on tech for "smart home" implementations ... devices that may be expected to run nearly constantly (though perhaps not 365/24 with 6 9's reliability), but which, for the most part, are /not/ safety critical. WRT Don's question, I don't know the answer, but I suspect runtime diagnostics are /not/ routinely implemented for devices that are not safety critical. Reason: diagnostics interfere with operation of they happen to be testing. Even if the test is at low(est) priority and is interruptible by any other activity, it still might cause an unacceptable delay in a real time situation. To ensure 100% functionality at all times effectively requires use of redundant hardware - which generally is too expensive for a non safety critical device. YMMV. George