Where is this integer coming from?

[showshocka]

Sorry for the delay guys...still need help... i did get help from this thread http://www.plctalk.net/qanda/showthread.php?p=483747&posted=1#post483747
here are the projects uploaded

 

[Dravik]

N7:50 comes from N17:1
(Ladder 2, Rung 48)
N17:1 gets set from N20:1(Ladder 2, Rung 45) conditionally based on the state of B3:7/3 or from C5:21.ACC(Ladder 4, Rung 22).

And N20:1 comes from a MSG instruction(Ladder 4, Rung 1) from a device labeled the T-car processor.

 

[Dravik]

How I came to this, Go to the datafile for N7 and cross-reference N7:50. You'll see a number of CMP instructions and 1 MOV instruction. The MOV instruction is the first place I'd check since its only used in one place.

From that MOV instruction(Which is Ladder 2, Rung 48) you'll see that comes from N17:1.

Now do the same to N17:1, You'll see it can be 'set' by 2 different instructions. One instruction sets it from the value of N20:1(Ladder2, Rung 45) and the other sets it from the value of C5:21.ACC(Ladder 4, Rung 22).

So on and so forth

 

[showshocka]

N7:50 comes from N17:1
(Ladder 2, Rung 48)
N17:1 gets set from N20:1(Ladder 2, Rung 45) conditionally based on the state of B3:7/3

And N20:1 comes from a MSG instruction(Ladder 4, Rung 1) from a device labeled the T-car processor.

(Ladder 2, Rung 45) I see they're using B3:44/0 as an AFI for some reason....(?) So how can that rung ever be true? or is B3:44/0 a floating bit?

 

[OkiePC]

...or is B3:44/0 a floating bit?

What?

They created another abstract data type without even consulting me...

 

[Dravik]

Ladder 2 Rung 45 looks like this according to the program you sent..

XIC B3/115 BST MOV N20:0 N17:3 NXB MOV N20:1 N17:1 BND

I don't see B3:44/0 used there at all.

 

[Lancie1]

Paul,

I think a Floating Bit must be like an Always-On trouble-shooter bit. It just floats around looking for someplace that needs a "1" to save the day.

 

[Dravik]

Paul,

I think a Floating Bit must be like an Always-On trouble-shooter bit. It just floats around looking for someplace that needs a "1" to save the day.

Thanks Lancie, now I have the mental image of 'Bit' from Tron w/ a cape flying around

 

[Lancie1]

(Ladder 2, Rung 45) I see they're using B3:44/0 as an AFI for some reason....(?) So how can that rung ever be true? or is B3:44/0 a floating bit?

Showshocka, I did a search in your program for B3:44, and turned up nothing in the entire program. What are you talking about? Could you have mis-typed and really meant B3:14/0? There is one case of that bit in Ladder File 5, Rung 023. The only AFI instruction that I found is in Ladder File 6, Rung 000.

 

[showshocka]

is this a trouble shooter bit?

 

[OkiePC]

It's impossible to say for sure, but that is certainly a contending possibility.

Is there a remote device that can change the state of that bit (besides RSLogix500)?

If there is no HMI or networked system writing messages to the undocumented address, then it possibly is some sort of "programmer enable" bit...

Have you ruled out the possibility of that bit being written by a word move or indirect addressing?

To view the file and word level possibilities, right click the address, go to data table, and hit the usage button. This won't tell you everything you need to know if there is indirect addressing in the file, but it can tell you if something is writing to the whole word or group of words containing the suspicious bit address.

To rule out the possibilities of indirect addressing, do a find all on this character "[".

I am speaking generally here, I have not opened your files to dig for myself yet, nor have I read the beginnings of this thread.

 

[Dravik]

Hey Show, the file you uploaded and the file you are working from are different btw.

 

[Dravik]

I at least, have PAI_2201 5-9-2007, Your screenshot shows PAI_2202..

 

[Lancie1]

Hey Show, the file you uploaded and the file you are working from are different btw.

That explains why I did not find the B3:44/0. We need to all get on the same file here, before someone gets mad!

 

[Nigasai]

Check if there is a COP instruction (copy) maybe n7:50 is part of an array of 50.. Maybe only but posible..