Implement event trigger when Data change

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Implement event trigger when Data change

Hi,

I want to implement event trigger when Data change in c code,

I don't want to set a fix trigger_value, 

does anyone know that how can I use privious data to compare current data?

or any suggestion?

 

Thanks.

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Sorry, there is nothing in DDS that does this for you.  You will have to write use code to directly compare an old value of data to a new value of data and implement a triggering mechanism.

You can use a listener callback and then store the old value in the callback and then when called compare the new value with the old value and then either callback a different function registered with the callback or signal a semaphore to wake up a processing thread when the value of data changes.

What I describe is general programming and has nothing specific to do with DDS.