Feedback node

[masandberg]

Is it possible to reinitialize a feedback node in Labview without leaving (ending) a while loop? Any advice would be appreciated. Thank you.

[altenbach]

Yes, feed the wire leading to it through a case structure. Wire it through in one case and initialize it to some control or diagram constant in the other case.

[mama miya]

newbee to LV needs help!  

i have some thing to add-on to the same variable n that something is the o/p from a case structure which has some calcultaions in that.. n when i do this feedback node is getting inserted automatically. how to avoid this f/b node? or how to reset this? what is the impact of this f/b on my program?

thanks

mama

[JÞB]

Mama,

Your replying to a thread that is 5 years old.  Please post a new thread with a better discription of your problem.  If english isn't your best language go ahead and post in your native toungue and please also post an example of the code that is giving you trouble.

[smercurio_fc]

I hope you realize you're posting to a 5 year old thread, and your question has nothing to do with what was being asked. The general topic is feedback nodes, but you have a completely different question, so you should have started a new thread.

Feedback nodes are automatically inserted when you try to create a wire loop. This behavior can be turned off via the LabVIEW options.

To be honest, I'm not sure what you're trying to accomplish with your VI. Can you better explain what you're trying to do?

[altenbach]

The feedback nodes are automatically inserted, because otherwise you'll get a broken wire because your wiring scheme makes no sense.

A "loop" in this context are code sections that depend on each other in a way that is incompatible with dataflow: The middle case structure selector terminal depends on a value that itself depends on the result of the addition, which depends on the output of the same case structure. Right?

This means the case structure cannot execute because one input is not yet available, and the input is not available because the case has not executed. Impossible! When LabVIEW auto-inserts a feedback node, it "solves" the dilemma by delaying part of the input by one iteration.

I am no friend of such auto-insertion, simply because it "fixes" an otherwise broken wire with a code change that might not be appropriate. As in this case, you should re-think the program from the ground up instead. 😉

Please tell us what your program is supposed to do. Looking at the current code gives us no clue! 😉