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???
05/30/08 06:21
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 		 #155278 - What about processing speed
Responding to: ???'s previous message
A method is devised to monitor the outputs of all three MCUs to see that they are producing the same results. One way to do this is to have a multi-ported RAM on each device and every once in a while all devices are to place their result(s) into the RAM. The results in the three RAM sets are compared by a supervisory MCU that can vote out one that works out of step and switch in the outputs of one of the other two MCU systems.

This should be done for each input the controller(s) give. Doing this will definetly take some amount of time. Wont this effect the overall performance of the system or slow down the speed. Do i need to use a external RAM for this.
For 8051 external RAM slowers the speed. I read it in a PDF file.





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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