Feedback Initialize

[jstarustka]

I am trying to bring data into the following logic circuit from two arrays.  The initial input to two of the xor gates must be 1,1 and then after the first iteration it takes in the previous output.  I have tested the circuit using a random number generator and it works great as long as I do not use arrays as input.  I am not seeing the initialization arrays receive the the previous output when I use arrays which is stopping my VI from working.  I have uploaded a screen shot of the VI below.  Thanks for any help.

Joe

[EdDickens]

Could you expand a bit more on what you mean by the statement, "I am not seeing the initialization arrays receive the the previous output when I use arrays which is stopping my VI from working."?

If you're saying what I think you might be saying, I don't think you understand how shift registers work. The arrays themselves will not receive any data from the previous loop iteration. Only the shift register will recieve that data.

If I misunderstood what you are try to say, please let me know.

Ed

[jstarustka]

My apologies, I posted the wrong screenshot.  I decided to play around with the shift register and the circuit works fine when I load the array with values.  Unfortunately I need to use the feedback loop, which after reading, my understanding is that you set up an initial value and then on subsequent passes the output becomes the input.  I need the initial value to be 1,1 and then on subsequent passes the output will become the input.  It works for one iteration only and when I get rid of the arrays for input and use a random number generator for input the feedback loop works perfectly with the initial values of 1,1.  I know that I am missing something trivial but I cannot seem to find the problem.

Thanks

Joe 

[EdDickens]

OK, I'm trying to get a better idea of exactly what you are trying to do, so I've tried to duplicate your code. Could you take a look at this and let me know if this is good representation of what you are trying to do?

The two small For loops are simulating the two array inputs that you have on the top of your loop coming from the Build Array functions.

Ed

Message Edited by Ed Dickens on 07-27-2007 08:20 AM

[jstarustka]

I think you have the jest.  Here is the VI with the input file. I need each value from the arrays sent through the logic circuit and then sent out to be interleaved with some other sections.  The logic circuit is acting as an encoder.

Thanks

Joe

[EdDickens]

I don't have the Modulation(?) toolkit installed. Could you attach the "MT BHC Encoder.vi" so I can see what this is doing?

Ed

[jstarustka]

Here is the vi.

Joe

[EdDickens]

OK, I have it running, and one thing I see that makes me wonder is the XOR gates that are fed from the shift registers.

When you XOR the input arrays with the single element array constants that are initializing the shift registers, you will always get a single element array out of the XOR gate. Maybe this is what you want, but since you mentioned you are trying to interleave the arrays, this seems like it might be at least part of the problem.

If this sounds like it might be problem, try initializing the shift register array as shown in the image and let me know what happens.

Ed

Message Edited by Ed Dickens on 07-27-2007 01:21 PM

[jstarustka]

I wired it up like you suggested and it worked, but not as expected.  I am getting multiple arrays with data in them which is a big step forward.  Unfortunately I am expecting my output to be fed into the shift register and then sent back into the circuit.  Basically the two output arrays should be shifted by 1 bit when comparing them to the two arrays coming from the shift register.  Is this a correct assumption.  Right now I am not getting that, I am getting different values but do not know where they are coming from. Here is a screenshot.

Thanks for all of your help.

Joe

[EdDickens]

Could you possibly provide a more detailed description of what you are trying to accomplish?

I'm having a hard time figuring out the problem because I don't know what the result needs to be.

Ed