Feedback Node Initializer Being Ignored ?

[CRoebuck]

Hi

I have a feedback node sat in a For Loop, the number of iterations is determined by an input array. The same input array is wired to the initializer terminal of the Feedback node.  The Feedback node delay is set to 3 and yet the output of the node only contains the first value of the array for the first 3 iterations. It's easier to show than describe.

So I would expect the output Array to contain the values 3,1,0,0,1,2 yet it actually contains 3,3,3,0,1,2

If I wire the scalar value 99 to the initializer then I get the expected 99,99,99,0,1,2

What am I missing ?

This is LabVIEW 2011 for MAC OS X

[swatts]

Hi Chris,

This is how I see it, the initialise will set the initial contents the first time the feedback node is run, the delay will then output that initial data for however many times it's set to (3 in your example)

I have to admit I haven't had a play with the extras on feedback nodes

Hope this helps, if I've got the wrong end of the stick prod me!

Regards

Steve Watts

SSDC Ltd

[Wayne.C]

I'd say that swatts hit the bullseye!

[P@Anand]

Hi CRoebuck,

   The name Initialize itself signifies that it will be executed only at the first execution. I really wonder how a CLA gets into this simple confusion.

[RavensFan · Accepted solution]

To expand on Swatts answer a bit more.  You are actually only initializing the feedback node with a single element because you have the array auto-indexing at the loop tunnel.

If you fed the entire array into the For Loop and the initializer terminal, it would have worked the way you expected.

[CRoebuck]

ha ah , the penny finaly drops. That was the differnce between the original problem code and my poor replication of it. 

The auto indexing tunnel, totally failed to spot it. Too busy looking into the feedback node, a feature of which I have little working experience. Thanks to everyone who made +ve contributions towards my enlightenment 😉

[CRoebuck]

It's easy when you focus on the output, Wood from the tree's and all that.

[johnsold]

What Ravens Fan said is hidden in plain sight in the detailed help for Feedback Nodes.

"Note  When you set Delay to two or more executions or iterations, you can wire an array to the initializer terminal to initialize each delay element to an arbitrary value."

Lynn

[Darin.K]

Actually if you move the initializer one loop out not only does it look better, but this sort of thing won't happen.

[JÞB]

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@Darin.K wrote:
Actually if you move the initializer one loop out not only does it look better, but this sort of thing won't happen.

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moving it out 1 loop disables the "globally initialize" on "first call" options that the OP selected. (Of course that might have been an additional unintended bug that moving the initiallizer would prevent as well):smileysurprised: