Implement event trigger when Data change

2 posts / 0 new
Log in or register to post comments
Last post
Tue, 02/25/2020 - 02:52
#1
Kay Wu
Offline
Last seen: 4 years 7 months ago
Joined: 08/11/2019
Posts: 28
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.

Organization:
Keywords:
Top
Tue, 02/25/2020 - 15:48
Howard
Howard's picture
Offline
Last seen: 10 hours 16 min ago
Joined: 11/29/2012
Posts: 617

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.

 

Top