two while loop can not synchroniclly run

[jimmykingboy]

hello guys,

as i want to test the forces on both sides of the maschine, i am programming with 2 while loops. First i designed on Loop(Loop1) for the right side of the maschine. Then copied it and set another one as Loop2 for the left side of the maschine. Wenn i run the whole Program, only Loop2 runs and nothing happened by Loop1. I testet with ''start single stepping'', the single stopped just before it entered Loop1, by Loop2 it has ran orderly. What's the problem.

can someone help me? Thank you.

[Dennis_Knutson]

You've created a data dependency between the bottom loop and the top so of course the bottom loop runs first and the top will not execute until the bottom finishes. A second loop is not even necessary and if you did manage to get them to run in parallel, you would get a resource reserved error. All that you have to do is add the second channel to one task and acquire both channels in a single loop.

[Dippi]

Hi,

there is an easy description for this behaviour.

A loop acts like any other node in LabVIEW.

All Inputs must be there before the output will be calculated.

Example:

Function "ADD"

First BOTH inputs must be there, then the outputs will be calculated.

Your problem:

If a while loop runs, no tunnel will output data.
this will be done after the loop stops.

If the 2nd loop is connected to this output of loop #1, this output is like an input for loop #2

=> That mean, that the loop will wait for this input and will get this input, when loop #1 stops.

As attachment you will find two examples
1) you can see the problem

2) NO problem, because no connection between the loops

Possible solutions:

You can use the following transfer mechanisms to transfer the data from one loop to another

- local variables, global variables (http://www.ni.com/white-paper/7585/en)

- Notifier

- Queues (http://www.ni.com/white-paper/3023/en)

Hope that helps

Best regards

Dippi

[jimmykingboy]

Thank you. I combined two loops together but still doesen' t work.It always shows:

[jimmykingboy]

Thank you for your reply. It seems that date that was read by USB Karte can only be used by one loop, because it always shows 

[dkfire]

You need to show us your modified code if you need our help.

We can't guess on what you are doing.

Attach the code and a picture of the block diagram.

[jimmykingboy]

I already uploaded it. you can find it upstairs.

[dkfire]

Code where you have combind the two loops ?

You are asking about error's comming from a modified code that only you can see.

It is hard to give you any help, if we can't see the how you have combind the two loops.

[jimmykingboy]

this is the combined Program

[Dennis_Knutson]

I told you that you would get a resources reserved error and I told you how to fix it. Did you bother to confirm what I said or did you search for the error code to see the numerous other new users that have made the same basic mistake?