Controllogix Arrays

[plcengineer]

I have an application that requires the addition of multiple arrays in a controllogix program. First of all, I have an array of 250 tag name Index_Pos_Recipe[0] through Index_Pos_Recipe[250].. I would like to do the following: Enter a number from an operator interface for the array index. For example enter in a 75.. I would then like to add Index_Pos_Recipe[0] through Index_Pos_Recipe[75] and put that number in one tag address. Another example would be enter in a 50, then I would need to add Index_Pos_Recipe[0] through Index_Pos_Recipe[50]..

I reviewed using a FAL instruction but I am not too familiar.. Please give some ideas of how to do this.. it seems simple but I have not been able to come up with anything.. I think the FAL would work but I tried putting that in my code and didn't understand what I needed to have so it didn't work... If someone knows the FAL and tell me how to set up this app, I would appreciate it..

tks,
plcengineer

 

[CroCop]

Can you use ST? A while loop sounds perfect for this application.

Index := 0;

While Index < OITindex do

Total := Total + Index_Pos_Recipe[Index];

Index := Index + 1;

End_While;

Edited to add index set at beginning (what good would it be if you could only call it once?)

 

[plcengineer]

I have never used ST.. I am a ladder guy.. How would I go about setting this up.. Or, do you have a ladder way like with a FAL that would work..


tks

 

[CroCop]

For STL you can create a routine, give it any name you want.
To execute the routine, put a JSR in your ladder.

Or I'll look into how the FAL works and see if I can understand it.

Marc

 

[CroCop]

I take it back. I don't think the FAL instruction supports a variable in the length position.

I'd use ST, it's really simple & a good chance to get experience with it.

 

[plcengineer]

I'll look into the STL but if you don't mind, see what you think of the FAL.. Or some type of ladder that I would understand..

 

[plcengineer]

CroCrop,

Can you give a few more details on how to do the ST?? I think I will try this.. Thanks

 

[CroCop]

OK, here's the trick.
The length must always be 1 or greater.
Move a variable into the Control.Length
Declare a control tag,
Declare an Index tag,
Declare a total tag,
Declare the array.

I've attached an example file.

 

[CroCop]

The Ladder & ST should be identical ithe end, it just executes little differently.

I'd bet the ST can blow through it much faster.

 

[Alan Case]

Hi CroCop.
Pardon me if I am wrong but in the ladder example I thought that the mode should be all and in the expression the part in the brackets should be [Control.Pos]

And here is another way that will do it in ST. I think it should be faster still. It is not zipped, just change the zip to ACD

Regards Alan Case

 

[plcengineer]

Hey Guys,

So, do I need to change the example from CroCrop?? Should the mode be ALL and the expression [Control.POS]??

tks,

 

[Alan Case]

The expression isnt [control.pos] just the bracketted part of the expression, ie replace index in the expression with control.pos
Read the FAL help file and it will explain this bit.

My understanding is that with the mode as INC then each false to true of the rung will add only 1 value to the total. With mode as all it is done in the one scan.

Regards Alan

 

[plcengineer]

I have version 13 and 13.03..Can you put this in that format?? Sorry

 

[plcengineer]

or, could you take a screen shot.. I don't think it would be very much code..

 

[plcengineer]

Could someone open this and take a screen shot so I can see it.. I have v13.003 rslogix5K