FAL Instruction in RsLogix 5

bansodevb

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Jan 2010
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Hi,

I am new to PLC 5. I have to convert PLC5 logic to controllogix .

Can anyone explain How FAL instruction works in PLC 5?

And what is the meaning of #N48:2 Address?
Attached is the sanpshot of the logic.


Thanks

Vinod B. Bansode

FAL Instruction.jpg
 
Last edited:
Can you zoom in on the FAL instruction and repost? I can't read the instruction as is.

The "#" sign indicates the starting address. The instruction will start writing the result of the expression to N48:2 and then N48:3 and so on based on the length setting.

It looks like the length says 16 so the FAL will write to N48:2, then N48:3, then N48:4 and continue through N48:17. I can't make out the expression though, but the expression is the math or arithmetic being performed.

OG
 
Hi,

I am new to PLC 5. I have to convert PLC5 logic to controllogix .

Can anyone explain How FAL instruction works in PLC 5?

And what is the meaning of #N48:2 Address?
Attached is the sanpshot of the logic.


Thanks

Vinod B. Bansode[/quote]

FAL.jpg
 
been a while since my PLC5 days,

The FAL instruction operates as the compute CPT instruction, only it acts on a file level, indicated by the hash # as opposed to the element (single store) level the compute CPT instruction does.

The #N48:2 is a file (a number of elements) brought into this subroutine from elsewhere to be acted on by the FAL

Hope this helps

Steve
 
been a while since my PLC5 days,

The FAL instruction operates as the compute CPT instruction, only it acts on a file level, indicated by the hash # as opposed to the element (single store) level the compute CPT instruction does.

The #N48:2 is a file (a number of elements) brought into this subroutine from elsewhere to be acted on by the FAL

Hope this helps

Steve

Thanks Steve for the reply.

What about the indirect addressing in the Rslogix5000 ? Is it possible in Rslogix5000.

As one can see in the snapshot indirect addresssing used in FAL instruction. When translate this into Logix 5000 its creates something like this N[N49_10][N49_13] which gives error.

Do any one has idea about this?

Thanks,

Vinod B. Bansode
 
Thanks Steve for the reply.

What about the indirect addressing in the Rslogix5000 ? Is it possible in Rslogix5000.

As one can see in the snapshot indirect addresssing used in FAL instruction. When translate this into Logix 5000 its creates something like this N[N49_10][N49_13] which gives error.

Do any one has idea about this?

Thanks,

Vinod B. Bansode

This shouldn't be a problem. It all depends on how the translator handles this. Basically it should translate into a 2 dimensional array of integers. The number of elements to process (AND with FF3F) is pre-loaded into N48:4 before the subroutine call. The idea is to clear bit's 2 and 3 of the selected array (the indexes of which are also pre-loaded - N48:2 and N48:3)

If I were doing this I'd re-write the thing in Structured text to make it more readable.

Cheers

(8{)} :) .)
Yosi
 
Only other thing i can think of that you might have trouble with is that the PLC5 is in octal and the control logix is not so you just have to watch your addressing a little bit. But i agree defintly would rewrite it the tags are easier to follow in the program.
 
Only other thing i can think of that you might have trouble with is that the PLC5 is in octal and the control logix is not so you just have to watch your addressing a little bit. But i agree defintly would rewrite it the tags are easier to follow in the program.

PLC-5 Digital I/O is octal. All of the internal addresses are decimal. The PLC-2 was the last A-B PLC that was all octal.
 

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