Counting Populated Elements In An Array

[wirelessliquid]

Hi Guys,

Does anyone know a good way to count populated elements in an array?
I have 2 arrays of 60 elements which hold strings.
When a string holds no data '' its population should be 0
when a string holds data 'ABCD' its population should be 1
I need the total population of both arrays.

Working in Logix 21.11

Seen a similar post for integers but with no clear answer.
http://www.plctalk.net/qanda/showthread.php?t=112140

 

[drbitboy]

https://www.plctalk.net/qanda/showthread.php?t=116943

summat like

(stringarray[ctl.pos].len > 1) + ARRAY_TOTAL

I.e. assuming the logical expression (stringarray[ctl.pos] > 0) is cast to an INT value of 0 or 1?

or this:

(stringarray[ctl.pos].len/(stringarray[ctl.pos].len + 1e-38)) + ARRAY_TOTAL

the {+ 1e-38} ensure it does not divide by 0 when .LEN is 0, without affecting the desired INT result of 1 when .LEN > 0.

 

[wirelessliquid]

So I've set it up how the other post said, I'm struggling with the expression which I think is what you have sent me in the last post.

(stringarray[ctl.pos].len > 1) + ARRAY_TOTAL

what do you mean by ctl.pos, would that be my FAL control FAL_L1.POS??

I've attached what I've got so far

 

[pturmel]

(stringarray[ctl.pos].len > 1) + ARRAY_TOTAL

Probably don't want .len in those expressions.

 

[wirelessliquid]

Even Removing the .LEN Still does not verify,
The post suggested uses another INT array rather than a String Array

 

[plvlce]

Probably don't want .len in those expressions.

I'm pretty sure he does. An unpopulated array element should have a length of 0, a populated element will have a length of at least 1.

EDIT: However, the error is caused by the fact that '>' (and the rest of the comparison operators) are not valid operators for the FAL instruction. See the table beginning on page 341

In other words, the assumption made by drbitboy in post #2 is not valid when using FAL.

The linked topic works not because it is an INT rather than a STRING, but because it is summing the actual contents of the array without any attempt to evaluate them beforehand.

 

[wirelessliquid]

I'm pretty sure he does. An unpopulated array element should have a length of 0, a populated element will have a length of at least 1.

EDIT: However, the error is caused by the fact that '>' (and the rest of the comparison operators) are not valid operators for the FAL instruction. See the table beginning on page 341

In other words, the assumption made by drbitboy in post #2 is not valid when using FAL.

The linked topic works not because it is an INT rather than a STRING, but because it is summing the actual contents of the array without any attempt to evaluate them beforehand.

That makes sense, So FAL functions cannot use comparison operators.
Does that rule out using the FAL to search the population of an array?

Any other ideas on how I can search the array population?

 

[plvlce]

Any chance the array elements will always have the same length? Or can be buffered so that they do? If so, you could sum the total number of characters and then just divide by the known length when done. A but of a kluge, but should work.

 

[wirelessliquid]

Yeah the Strings are actually all the same length, they are RFIDs so all 16 characters.

How would I write out this expression?

 

[destination unknown]

Try FSC..

When
.fd add 1 to total
reset .in //to continue searching

 

[plvlce]

Basically just 'EM005_STATION5_Robot1OutPuckRFID_FIFO[FAL_L1.POS].LEN + FAL_L1_Total'

Then DIVide FAL_L1_Total by 16 as an operation separate from the FAL.

EDIT: As destination unkown points out, FSC could work instead of FAL if there is any part of the string that will always be the same.

 

[travispedley]

y := 0;
FOR x := 0 to 59
	do	
		If StringArray[x].LEN > 1 then
			y := y +1;
		end_if;
end_for;
PopCount := y;

 

[durallymax]

RA likely has more elegant ways to do it, but a For loop incrementing an int if indexed position not equal to empty string is a simple way that works on others as well.

 

[destination unknown]

Try the expression in the FSC
stringarray[ctl.pos].len > 1

 

[drbitboy]

or, to do it in one step, assuming .LEN can only be either 0 or 16, though less efficiently:

(EM005_STATION5_Robot1OutPuckRFID_FIFO[FAL_L1.POS].LEN/16) + FAL_L1_Total
​

Alternatively, if this is indeed a FIFO, then add/subtract 1 to a running total when a non-empty string is FFLed-onto/FFUed-from the FIFO.