RSLogix 5K FBD - Error messag

Hello All,

OK, this one's got me stumped. With all of my experience with A-B gear this is the 1st time I've run across this.

A customer of mine is using FBD. His code is on two separate sheets. He wants to monitor the state of a function block input (after all of his logic) and use the value of the input on a function block on another sheet as shown.

The error message that he gets is : Another language element's data overlaps with this one.

Where can I find the rules (and reasoning) behind this.

Thanks,

(8{)} .)
(Yosi)

(8{)} ( .) said:

Hello All,

OK, this one's got me stumped. With all of my experience with A-B gear this is the 1st time I've run across this.

A customer of mine is using FBD. His code is on two separate sheets. He wants to monitor the state of a function block input (after all of his logic) and use the value of the input on a function block on another sheet as shown.

The error message that he gets is : Another language element's data overlaps with this one.

Where can I find the rules (and reasoning) behind this.

Thanks,

(8{)} .)
(Yosi)

Click to expand...

Looks like a CAPITALIZATION problem, to me.

Greetings Yosi ...

DISCLAIMER: this is all guesswork based on what I think you're describing ... if this doesn't help, could you post a screen shot – or better yet the programming code? ...

it's hard to tell for sure without some more detail – but it SOUNDS LIKE you're running into the Function Block Diagram's equivalent of the "double-coil syndrome" from Ladder Logic ...

I can easily reproduce the error message that you've reported by programming something like the figure shown below ... notice that TWO things are both trying to control the ONE output tag My_Answer ...

this is not allowed ...

note that it doesn't matter whether or not the two "controlling" things are located on separate SHEETS of the same Function Block Diagram ... that is still not allowed ...

on the other hand, you COULD locate the two "controlling" things on TWO separate Function Block Diagrams ... in other words, place the two "controls" in TWO separate ROUTINES ...

that would be "allowed" – but whether it would meet your needs remains to be seen ...

the basic idea would be that you could execute either ONE of the Function Block Diagrams – or the other ...

TIP: if you're getting exactly the same Error message that I am, note that it goes on to say that: "You can use the Cross Reference to find other instances of this data." ... has your customer tried that approach – and specifically tried looking for two or more instances in the Cross Reference which have "Y" (yes) in the Destructive column? ... of course your version of RSLogix5000 might be different ...

.

shown below is another idea that MIGHT be useful to you ... once again, I'm just GUESSING about what your customer is really trying to accomplish ...

the method shown below uses an SEL (Select) instruction to decide which ONE of the TWO control streams will actually control the ONE output ...

I hope this helps ... if not, please consider posting more information ...

.

Example code

Well hello Ron!

Been a long time

1st of all I didn't realize that I couldn't use the same output in FBD. That's not, essentially the issue.

What I show in my screenshot is something different. I'm trying to examine an INPUT (SSUM_01.select1) to another block that was executed previously. That input should hold a value and I want to use that as an input to a new block. There are some logic blocks that precede that input and I want to examine the results.

I've uploaded a very simple example using BOR instructions where I want to look at the state of an input and use that as an input to another BOR. I can sort-of imagine reasons why that would be illegal but I don't necessarily accept them.

Thanks!

Yosi

here are a few more ideas ...

I think that the reason you're unable to verify your "problem" arrangement is that the software is (correctly) expecting the location BOR_01.In1 to be CONTROLLED by "something" which will be (should be) wired into the pin on BOR_01 ...

regardless of whatever that "something" eventually turns out to be, its signal status is going to "override" or "control" the status of the In1 pin/location of BOR_01 ...

therefore, it would make more sense (at least to the software) for you to re-use the status of "whatever" is feeding the input of BOR_01 – and use that same signal as the input of BOR_02 ...

if this doesn't nail it down, maybe you could tell us WHY your customer is trying to set this up by using the "input" LOCATION of one instruction as the "input" to ANOTHER location ...

I've got a hunch that once the underlying LOGIC/THOUGHT/IDEA behind what the customer is trying to accomplish is fully understood, then making the programming code work properly won't be too difficult ...

the suggestions I've made below WILL verify (at least on my system) - and hopefully they'll be useful in meeting your requirements ...

.

and one more technique ...

this one will also verify (at least on my system) ...

.

Hi Ron

Thanks for your reply. We figured that connection out. The problem is that the customer put is FB's on two separate pages. Evidently this is something you can do with other controllers. I usually don't do extensive FBD anyway. I use it mostly to program PID loops and not to do what is better done in ladder.

Thanks and take care!

Great hearing from you.

Yosi