Indirect addressing

[RobWad]

Can anyone help with this indirect addressing? This is what i got on the plc5 to controllogix translation tool. Any help is appreciated.​

PLC 5​

BTD

Bit Field Distributor​

Source

N[N40:47]:[N40:44]

0<
​

​

Source Bit ​

​

0

​

​

Dest ​

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N40:21

0<
​

​

Dest Bit ​

​

0
Length 8

RS 5000 TRANSLATION​

Bit Field Distribute
Source ​

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N40_47

​

​

<N40[47]>
44
Source Bit ​

​

0

​

​

Dest ​

​

N40[21]

0
​

​

Dest Bit ​

​

0
Length 8

​

​

​

​

​

​

​

​

​

​

 

[Lancie1]

Sometimes you have to edit the translation and fix the addresses to match the old program.

 

[RobWad]

rs5000 does not recognize this N[N40:47]:[N40:44]

 

[Ken Roach]

This isn't going to be an elegant translation because of the way Integer files are translated into single-dimensional Arrays.

The PLC-5 BTD instruction allowed you to specify both the Data Table Number and the Data Table Element.

But when each Data Table got converted to an INT[x] single-dimensional array tag, you lost the ability to indirectly address the "Data Table Number".

If you want to retain this sort of indirection, you're going to have to go back and convert the "N40[x]" tag into a two-dimensional array like "NForty[x,y]".

If it were me, I'd use this opportunity to translate the code into something more native and suited to ControlLogix.

 

[dmargineau]

I would strongly consider Ken's suggestion.

Otherwise, starting at page 45 of the link below, the conversion from SLC/PLC indirect addressing to Logix tags systems is explained.

http://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1756-rm085_-en-p.pdf

 

[RobWad]

What would be a more suited for controllogix for this? Thanks for your input.

 

[dmargineau]

You will have to create the Source Two-Dimension Array Tag corresponding to the PLC5 N[Nx:y]:[Nz:w], giving it a more meaningful name (you could also rename the Destination while at it) and then deploy the BTD via the "PLC5 Mechanism" which was writing the "old registers" Nx:y and Nz:w while remembering that PLC5 uses INT (16-bit) data structures while Logix Class CPUs are 32-bit (DINT) based.

More information about Logix Data/Tag structure at:

http://literature.rockwellautomation.com/idc/groups/literature/documents/pm/1756-pm004_-en-p.pdf

 

[mellis]

What would be a more suited for controllogix for this? Thanks for your input.

That would depend on what the code is doing and why it needed to change both the data file and the index.

For instance, if the only reason it changed the data file was that one data file was too small to hold all the data (1000 elements in PLC5), then the answer is easy: Just make the array bigger and eliminate the "data file" index and use one index.

If having more than one index makes sense for what you are doing, then go for the array[index1, index2] solution. Either way, definitely use meaningful names instead of N40.

While you are looking at what the code actually does, consider that there may be a much simpler way to do it.

 

[RobWad]

Thanks to all for your input. I have found this site very helpful!