RSLogix5000 dynamic tagging in AOI

I am trying to create a simple AOI that takes in a standard compound data type and a number (as either an INT or STRING, whichever is more efficient), and use the number as part of a sub-data type call:

The data type I am particularly looking at is the AB:1769_IF16:I:0 (AB's data type for the 16 channel Analog Input card)
That data type has several sub tags that are grouped into channels for example:
[Parent_Tag].Ch00Data
[Parent_Tag].Ch00Overrange
[Parent_Tag].Ch00Underrange

I want to use the number input to replace the number in the sub tag:

[Parent_Tag].Ch[Number]Data

Is there a way to do that in RSLogix5000?

You can't do indirection like that. I don't think there is any PLC that can do that, maybe CodeSYS based controllers (which I've never used).

Looking at your example, I don't see the benefit. You would have to input the base tag, just input it into the SCL instruction.

Phrog30 said:

You can't do indirection like that. I don't think there is any PLC that can do that, maybe CodeSYS based controllers (which I've never used).

Looking at your example, I don't see the benefit. You would have to input the base tag, just input it into the SCL instruction.

Click to expand...

In the Siemens world, you can pass the whole structure in as an IN/OUT, and then parse it accordingly on the inside of the FB. You wouldn't be able to parse out the number part unless it's set up as an array.


No idea how those concepts map to AB AOIs.

mk42 said:

In the Siemens world, you can pass the whole structure in as an IN/OUT, and then parse it accordingly on the inside of the FB.

Click to expand...

So Siemens allows indirection using strings/text?

Phrog30 said:

Looking at your example, I don't see the benefit. You would have to input the base tag, just input it into the SCL instruction.

Click to expand...

I only posted a portion of what I eventually want to do to keep it simple. I am using the .ChXXData .ChXXUnderrange .ChXXOverrange and .Fault.X sub tags, and this is repeated 40 times in the code. I think you are right though, RSLogix does not have a way to concatenate strings and convert them to a structure sub-component.

Take a look at the plantpax analog instructions for inspiration. You are going to have to map io at some point, but you really only need the “raw” data. No need for the under/over range and fault flags.

mk42 said:

In the Siemens world, you can pass the whole structure in as an IN/OUT, and then parse it accordingly on the inside of the FB. You wouldn't be able to parse out the number part unless it's set up as an array.


No idea how those concepts map to AB AOIs.

Click to expand...

In the Siemens world wouldnt't he create a structure for the input channel that mapped the original one and then create an array of them and link the first channel to the first element of the structure?

I haven't picked up TIA in a few months but seem to remember something like this before.

He should be able to do something similar in AB but it would require an additional COP, starting at the beginning of the first channel data going into the first element of an array of structures.

Keith

You can't do it with indirect style addressing like you want, but you can use the MUX block to select which input/under/over tag to use for the logic. You will have to get a little clever to convert your 0-15 to to sets of 1-8 for two MUX blocks, but otherwise entirely possible.



EDIT

There's also select (SEL) and enhanced select (ESEL) that work similarly if you aren't using the newer processors.

kamenges said:

He should be able to do something similar in AB but it would require an additional COP, starting at the beginning of the first channel data going into the first element of an array of structures.

Click to expand...

Fair point, I do that now with a HART gateway on site actually.