Generate 2D Raster Pattern in LabVIEW

[John_P1]

Overview: The following example has three modes for generating a 2D Raster Pattern in LabVIEW.

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Description:

The following example has three modes for generating a 2D Raster Pattern in LabVIEW.  It is meant to be used to build a waveform for a 2-channel analog output device so that one channel may control the X axis, and one channel the Y.

The modes are as follows:

Single-Direction (Uniform) -- This mode updates the Y output only after the X output is at its original position.  X will take a uniform amount of time to return back to the original position.

Single-Direction (Fast Reset) -- Similar to above, but this mode will reset X as quickly as possible (1 sample clock tick).  May not be advisable for some hardware setups.

Bi-Directional -- This mode will update Y every time X gets to its maximum or minimum value.  After X gets to its maximum value, it would then scan the next line of Y on its return to the original position.

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Requirements: LabVIEW 2012 (or compatible), Hardware: none.

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Steps to Implement or Execute Code:

1. Insert the parameters.
2. Run the VI.
3. Look at the result on the graph.

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Additional Information or References:

Also see the following example for a use case that involves hardware using DAQmx:

Synchronize Analog Output Sample Clock with TTL Pulse Count

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**This document has been updated to meet the current required format for the NI Code Exchange.**   

[SteveP]

John,

It looks like the last cycle of your raster has extra points on it - as many extra as the number of Y steps.  For the X scan, these are being generated by the outer For Loop's Index counter auto-indexed at the top right of that outer For Loop.  I did not see how or why they were being generated for the Y scan, so I modified the code for my use by simply extracting a sub-set of the array that is (X Number of Steps * Y Number of Steps) long.  This results in the last point of the Y raster being at Y Minimum (and only one such point at its ned that is that value) and the last X point remaining at the X Maximum (instead of ramping down to X Minimum).  Is there an intended reason these extra points are there ?

Steve

[John_P1]

Hi Steve,

Thanks for the feedback!  The extra points were intended to "reset" the scanner back to the original position.  I didn't want to instantly transition from the maximum to minimum value since this could be problematic when interacting with actual hardware.  This code was written for a specific application so more likely than not some modifications will need to be made depending on your exact requirements.  I hope it provided a good starting point for your application.

[John_P1]

Hey Steve,

I added an extra button on the front panel so you may now choose not to reset the Y output if you don't want to.  Thanks again for the feedback!

[SteveP]

John,

A subtle note is that enabling Reset Y at End of Scan? results in the Y array size being larger than X.  When they are combined with Build Array, the end of the X array is filled with a value of 0.  If X Minimum was set to something other than 0, that results in those extra points having a different value than the last X point in the raster.

Steve

[John_P1]

Hi Steve,

I fixed the behavior--good catch.

[MattA1]

Hi John,

A colleague of mine has provided me with a copy of this .vi as a starting point for a LabVIEW project, but I only have LabVIEW 7.0, and this version is incompatible with that. Any suggestions as to where I can find a 7.0-compliant version?

Matt