PLC 5/15 to PLC 5/20 E download issues

Hello. I am trying to download the project from a PLC 5/15 on DH+ network to a 5/20 E with the goal of getting the controller on the network. Remote access, etc.

I am encountering download errors prohibiting me from completing. It is the most recent upload from 5/15. It will not accept 4 rungs. Stating non-existent elements of array registers. I've attached pics. Is this due to to memory size mismatch?

If I delete the 4 rungs, program downloads but I get unexpected process control when put in chassis for real time operation.

I'm not grasping why the elements would not exist if its exact same program. What is happening during download transition?

Any insight is greatly appreciated as always.

Thanks for posting such good screenshots !

It's been a decade+ since I worked directly with RSLogix 5, but I have some ideas.

First, I recommend changing the controller type offline, rather than triggering it to be done automatically when you download to the controller. You'll get the new port settings and everything ready to go as well, since on PLC-5 those are part of the user program rather than NVRAM storage on a module or daughtercard.

The automatic re-sizing of the data tables is probably the issue. I suspect that the RSLogix 5 is looking at the elements of N25 that are addressed explicitly, and shrinking N25 until it only has the necessary number of elements. Then a subsequent program check looks at the indirect pointers and discovers that that the last value in the pointer is greater than the size of the data table.

Go check the size of N25 in the original program, and be sure the converted program has the same size.

Or, experiment with un-checking the "resize data tables" box during conversion from PLC-5/15 to PLC-5/20.

I agree. The sizing of the N25 file would have to have been done manually in the 5/15 to accommodate the indirect addressing. Automatic resizing is simply looking at the direct addresses and resizing based on that. Uncheck the box. Otherwise you'll need to check each data file to ensure the size in the 5/20 matches that of the 5/15.

OG

The resize datatables on download UNCHECK that box. Its taking the data tables to the last used size. And indirect is not shown as used typically.

I tried all combinations of the checkbox with no change.

Ken got me on a good path of register size.

I offline changed data size of N25 and N26 from 7 to 10. That eliminated the errors and I downloaded. The process is working as intended. Thanks to all who responded.