Re: "Am I still working okay?" asked the micro controller...
From: Spehro Pefhany (speffSNIP_at_interlogDOTyou.knowwhat)
Date: Wed, 19 May 2004 18:58:17 GMT
On Wed, 19 May 2004 21:12:52 +0300, the renowned Paul Keinanen
>On Wed, 19 May 2004 14:54:55 GMT, CBFalconer <email@example.com>
>>>> One way to check hardware is to run another identical processor
>>>> and compare that they behave the same. If you have three or more
>>>> then you can perform voting so that the most popular answer is
>>>> the one that gets used.
>>> That is cool idea !..
>>And not so simple. What takes the vote? What if it fails?
>Use mechanical or pneumatic voting, not electric.
>For instance, if you want to control a bidirectional relay, use a core
>with three separate coils, each controlled by a separate processor. If
>the current in two coils flow in opposite direction, the resultant
>magnetic field is zero. Then the third coil will determine the
>resultant force alone.
On one machine I'm very familiar with there are three safety
interlocks (one electrical (not electronic), one hydraulic, and one
mechanical). Only when all 3 agree it is safe is the electronics
allowed to do what it wants.
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