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Thread: How to detect the value of a variable is stagnant or not?

  1. #1
    Join Date
    23.04.2009
    Posts
    56

    Default How to detect the value of a variable is stagnant or not?

    Hello,

    I receive a variable of an equipment by ZenOn supervision. Normally the value of this variable changes every second. If its value doesn't change during a long time, for example one minute, that means the equipment meet some problems.

    So, my question is: How to easily detect a variable value is stagnant or not? If it is stagnant, I want to create an alarm.

    Thanks a lot at advance!

  2. #2

    Default Re: How to detect the value of a variable is stagnant or not?

    you can use a variable from the mathematics driver, in combination with a delayed limit.

    At the formula for the mathematics variable (datatype float), choose "difference" from the category "data reduction".

    set a time unit, calculation interval and difference interval. e.g. seconds, 2, 2

    This variable in the runtime will be unequal to zero as long as the variable is changing. As soon as the variable stops changing, the result of the calculation of the formula in the mathematics variable will be zero.

    Now link a limit or reaction matrix to this mathematics variable, to generate an alarm after a delay of e.g. 60 seconds when the value is zero. (delays at reaction matrix are introduced with zenon 6.50)

    In this case, an alarm will be generated when the value has not changed for 60 seconds (difference is 0 for a period of 60 seconds)

  3. #3
    Join Date
    23.04.2009
    Posts
    56

    Default Re: How to detect the value of a variable is stagnant or not?

    Thank you a lot Mark for this efficace solution. I have tried, it works well.

    Best regards

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