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Re: Diagnostics

From George Neuner <gneuner2@comcast.net>
Newsgroups comp.arch.embedded
Subject Re: Diagnostics
Date 2024-10-18 17:42 -0400
Organization i2pn2 (i2pn.org)
Message-ID <77k5hjprfq0ipjp6pcdd03lnph1i76ssuu@4ax.com> (permalink)
References <veekcp$9rsj$1@dont-email.me> <veuggc$1l5eo$1@paganini.bofh.team>

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On Fri, 18 Oct 2024 20:30:06 -0000 (UTC), antispam@fricas.org (Waldek
Hebisch) wrote:

>Don Y <blockedofcourse@foo.invalid> 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
<whatever> 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

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Thread

Diagnostics Don Y <blockedofcourse@foo.invalid> - 2024-10-12 12:58 -0700
  Re: Diagnostics antispam@fricas.org (Waldek Hebisch) - 2024-10-18 20:30 +0000
    Re: Diagnostics George Neuner <gneuner2@comcast.net> - 2024-10-18 17:42 -0400
      Re: Diagnostics Don Y <blockedofcourse@foo.invalid> - 2024-10-18 15:30 -0700
        Re: Diagnostics antispam@fricas.org (Waldek Hebisch) - 2024-10-19 01:50 +0000
          Re: Diagnostics Don Y <blockedofcourse@foo.invalid> - 2024-10-18 19:38 -0700
            Re: Diagnostics antispam@fricas.org (Waldek Hebisch) - 2024-10-19 03:53 +0000
              Re: Diagnostics Don Y <blockedofcourse@foo.invalid> - 2024-10-18 21:17 -0700
                Re: Diagnostics antispam@fricas.org (Waldek Hebisch) - 2024-10-24 17:52 +0000
                Re: Diagnostics Don Y <blockedofcourse@foo.invalid> - 2024-10-24 14:49 -0700
        Re: Diagnostics David Brown <david.brown@hesbynett.no> - 2024-10-19 14:07 +0200
        Re: Diagnostics George Neuner <gneuner2@comcast.net> - 2024-10-19 15:25 -0400
          Re: Diagnostics Don Y <blockedofcourse@foo.invalid> - 2024-10-19 14:32 -0700
            Re: Diagnostics Don Y <blockedofcourse@foo.invalid> - 2024-10-23 05:53 -0700
        Re: Diagnostics Nioclásán Caileán de Ghlostéir <Master_Fontaine_is_dishonest@Strand_in_London.Gov.UK> - 2024-10-20 19:15 +0200
      Re: Diagnostics antispam@fricas.org (Waldek Hebisch) - 2024-10-19 01:25 +0000
      Re: Diagnostics David Brown <david.brown@hesbynett.no> - 2024-10-19 13:57 +0200
    Re: Diagnostics Don Y <blockedofcourse@foo.invalid> - 2024-10-18 15:15 -0700
      Re: Diagnostics antispam@fricas.org (Waldek Hebisch) - 2024-10-19 03:00 +0000
        Re: Diagnostics Don Y <blockedofcourse@foo.invalid> - 2024-10-18 21:05 -0700
          Re: Diagnostics antispam@fricas.org (Waldek Hebisch) - 2024-10-19 13:53 +0000
            Re: Diagnostics Don Y <blockedofcourse@foo.invalid> - 2024-10-19 09:55 -0700
              Re: Diagnostics antispam@fricas.org (Waldek Hebisch) - 2024-10-24 16:34 +0000
                Re: Diagnostics Don Y <blockedofcourse@foo.invalid> - 2024-10-24 14:28 -0700
          Re: Diagnostics George Neuner <gneuner2@comcast.net> - 2024-10-19 15:58 -0400
            Re: Diagnostics Don Y <blockedofcourse@foo.invalid> - 2024-10-19 16:26 -0700
              Re: Diagnostics Nioclásán Caileán de Ghlostéir <Master_Fontaine_is_dishonest@Strand_in_London.Gov.UK> - 2024-10-20 20:08 +0200
          Re: Diagnostics Nioclásán Caileán de Ghlostéir <Master_Fontaine_is_dishonest@Strand_in_London.Gov.UK> - 2024-10-20 19:11 +0200
            Re: Diagnostics George Neuner <gneuner2@comcast.net> - 2024-10-20 15:44 -0400
              Re: Diagnostics Nioclásán Caileán de Ghlostéir <Master_Fontaine_is_dishonest@Strand_in_London.Gov.UK> - 2024-10-20 23:14 +0200

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