3-dimensional matrix programming

Hello All!

I'm using an Allan-Bradley PLC (ControlLogix L61) and would like to know if its possible to make a 3 dimensional matrix. I want to populate each cell (i.e. 10x10x10 would have 100 cells with predefined values) and I would like the program to be able to pull the value from the cell depending on what the user input is.
Example: a 10x10x10 matrix is populated by me with 100 random values. I would like to pull the value from the [5,4,3] spot at my command.

This will get me basic functionality of my end goal but I might be able to finish it up if I know where to start.

Any ideas?

You can create a 3 dimensional array for a start.

Welcome to the PLCTalk forum community !

The general answer is "yes, you can do that". ControlLogix tag arrays can contain up to three dimensions.

The syntax is exactly as you describe:

"MyDataArray[3,4,5]" is a reference to the data element with offset [3] in the first dimension, offset [4] in the second dimension, and offset [5] in the third dimension.

You can also use a Tag in place of any of the array index values;

XDim := 3 ;
YDim := 4;
ZDim := 5;

MyDataArray[XDim,YDim,ZDim] is the same as MyDataArray [3,4,5].


When using array tags, I always limit-check my index values to be sure they are in the range of the array, so that I don't inadvertently fault the controller by forgetting that a ten-element array has elements 0 through 9 and no element 10.

And because it's not totally intuitive; you create an array by entering a Data Type with the array dimensions in square brackets.

Create a tag and make the data type "DINT[10,10,10]" and you'll have a three-dimensional array with 1000 elements total.

I would have to make a UDT wouldn't I? With the exact size of the array I'll be using.

Ha thanks for the speedy response on that. You beat me to it!

This might be easier than I was expecting. My ultimate goal is to use 3 live values from three different processes to define the location in the multi-dimensional array. Pull that value and hold that value until the next reading.

coibarra said:

This might be easier than I was expecting. My ultimate goal is to use 3 live values from three different processes to define the location in the multi-dimensional array. Pull that value and hold that value until the next reading.

Click to expand...

As we say over here, "as easy as falling off a log".


You can have arrays of 1, 2, or 3 dimensions of any data-type, including structure UDT tags.


The only limitation is the maximum size of a single array tag cannot exceed 2MBytes !!


Just watch out for those indices, a 120 element array dimensions go from 0 to 199. I often create them 1 bigger than needed, and use 1 to 200, for example, wasting the "0" locations.



Having said that, they are sometimes very useful, eg. to hold "zero-filled" data that can easily be COP'd or CPS'd into another location to clear it.



I've even used the "0" location in a recipe array as en "edit buffer", so the operator never edits the source data, and only commits it once he's finished editing.

Coibarra 10x10x10 matrix is populated by me with 100 random values.


Shouldn't a 10X10X10 need 1,000 values?
Poet.