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???
05/28/08 18:46
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 		 #155234 - always operating or failsafe
Responding to: ???'s previous message
always operating
very tough, quoting Oliver To eliminate coding errors, each of the 3 controllers should be coded up by a separate software team. There is no other way.

failsafe
can be something as simple as a thermal switch to turn the heater off if the temp passes absolute max.

inbetween:
.. relying on watchdog reset
.. a simple thermal switch that will turn the heater on if temp below the minimum the solution can handle
.. an alarm

you need to either get 3 teams or lower your expectations.
always operating even is failed even by NASA on occasion.

no one but you(r customer) can determine what will be enough, by your posts nobody here can make that judgement.

what will it be?

Erik

List of 32 messages in thread
TopicAuthorDate
stanby controller for emergency            01/01/70 00:00      
   ALE pulse            01/01/70 00:00      
   What are the expected problems?            01/01/70 00:00      
   The problem here is...            01/01/70 00:00      
      What about processing speed            01/01/70 00:00      
         processing speed should not be an issue            01/01/70 00:00      
   How do you know if it has failed?            01/01/70 00:00      
      my querry            01/01/70 00:00      
         Use a watchdog            01/01/70 00:00      
            I think watchdog not suitable            01/01/70 00:00      
               watchdog            01/01/70 00:00      
                  if it is critical system            01/01/70 00:00      
               Backup controllers            01/01/70 00:00      
         does that going to help            01/01/70 00:00      
            Where are erik and Andy            01/01/70 00:00      
               Irrespective....            01/01/70 00:00      
                  What you say is correct            01/01/70 00:00      
                     engineering procedure            01/01/70 00:00      
               Where are erik and Andy - asleep            01/01/70 00:00      
   much simpler            01/01/70 00:00      
   always operating or failsafe            01/01/70 00:00      
   Have you considered this ...            01/01/70 00:00      
      there is always a gotcha            01/01/70 00:00      
         Yes, but it always depends ...            01/01/70 00:00      
            hardware description is needed            01/01/70 00:00      
               Is this feasible            01/01/70 00:00      
                  No,            01/01/70 00:00      
                  You have reinvented a watchdog            01/01/70 00:00      
                     this is running in circles because ....            01/01/70 00:00      
                        Nothing's perfect            01/01/70 00:00      
                           not if you are only concerned with hardware failur            01/01/70 00:00      
                              it's all about testing            01/01/70 00:00      

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