SLC 5/04 with 64k of memory to SLC 5/05 with 16k - Issues?

Customer is trying to save money and get a PLCs with less memory if the existing program will fit.

They are concerned that the PLC program may be using data from tables that would be removed or resized when moving from 64k to 16k. Is that a real issue? They want us to look through the PLC programs and see if they are using some type of direct references to an address that may no longer be there and I’m not sure how to look for that or anything else that could be an issue when moving to a PLC with less RAM. I’d hope Studio would warn you about addresses used but it just says there may be a loss of data or I/O configuration and gives you the option to not resize. ???

With RSLogix 500 (not Studio) open do a Find All search for N20:

If that file is used anywhere in indirect addressing it will show in the results. If not is will pop up the not found window. If not found you can delete the file without worry.
At first open each file and click the Usage button and see if any X, W or FW show up.

I would do this for every file over F8:

Changing the CPU should not change the IO table at all.

However, going from a 5/04 to a 5/05 first make sure the DH+ comm's are not used, and double check the DF-1 or DH484 channel settings to make sure they match.

Yes, RSLogix 500 Pro, sorry.

No N20 found and there is no N20 file in the Data Files folder. What is the importance of the N20 file?

“At first open each file and click the Usage button and see if any X, W or FW show up.”
What am I looking for?
F8 has many an X on the FLOAT Usage page.

Good catch. Yea the 5/05 doesn’t have the same ports and the customer will get that same data through Ethernet.

I did an online chat with Rockwell and they said there was nothing to look for if the program fits. What is the warning about loss of data for (just switching CPU types?) and how do you know when/if to resize the data tables? I like how their KB tells you to check the box when you want to resize the data tables.

Right, as long as the program fits, there really isn't anything else to consider outside of DH+ v Ethernet. The 5/04 and the 5/05 are functionally pretty much the same.

I don't believe there was any significance on N20. It was just an example of checking usage. If you see the "F", "W", or "X" then it is being used within the logic. If you open a data file you will see a Usage button. That is the easiest way to see what is and what isn't being used.

The software will automatically resize the data tables to fit the small controller if the memory required for the data files exceeds available memory. If you prefer, you can uncheck the box and do it manually.

One very small caveat though to what Aabeck mentioned about usage......If another controller is writing over the network to a data file, usage won't be able to detect that. It will appear unused. But, you would have to have logic written to do something with that data and that would make the usage show the "X" as used. So this is very unlikely.

OG

Yes, as Operaghost said, I was using N20; as an example.

Check every N, B, T, C, F & R file from x9: up for any usage, then if it doesn't show any X, W or FW do a search all for the entire file. If not found it is not used.

You may have to reconfigure some statements, such as messages.
we had an issue going from a 5/04 to a 5/05 several years ago.


I wouldn't walk away after the program is installed until I was sure it was running correctly.
James

When I am concerned about indirect addressing in a RSLogix5 or 500 program I CTRL+F (Find) and search for "["
Indirection will always be contained within square brackets.
Now if there are external devices (HMI, etc) that talk to this machine you will have to look in their applications for references that might become unavailable.

I generally do not allow the software to resize data tables when I change controller types. I like to keep my spares. Afterward, if the file won't compile because it is still too big, I can manually pick and choose which files to shrink and delete.

Thanks for all the info folks.

I’m not much of a PLC guy and just trying to find out what stuff to look for.

Sorry, still unsure what I’m looking for. All the files past and including F8 have a hand full of X’s marked in the files. No W or FW to be found.

‘[‘ was not found.

“if the file won't compile because it is still too big”
I was able to change the RAM size to 16k, not check the resize data tables and go online. I am using RSLogix Emulate500, is that a good enough test?

Tanquen said:

“if the file won't compile because it is still too big”
I was able to change the RAM size to 16k, not check the resize data tables and go online. I am using RSLogix Emulate500, is that a good enough test?

Click to expand...

I so rarely use Emulate 500 that I can't say for sure if that is a valid test but I would think so.

Here is a valid way to test:
Change the controller type (to pick the smaller CPU in the same family), unchecked "Resize Data Tables" and hit okay.

Then right click on the Program Files folder icon in the project tree and click "Verify Program", you will get an error if you run out of memory. Matter of fact, I think you might even get the "Results" pop-up on the previous step if there is not enough memory.

But to be sure, once done with that, double click Controller Properties and you should see numbers for Memory Used and Memory Left that will tell the tale for sure.

"Then right click on the Program Files folder icon in the project tree and click "Verify Program"""
No errors!

Memory Used: 5749 Instruction Words Used - 1722 Data Table
Memory Left: 6539 Instruction Words Left

Tanquen said:

Customer is trying to save money and get a PLCs with less memory if the existing program will fit.

Click to expand...

Not that it helps at all, but what a stupid place to try and save money!

janner_10 said:

Not that it helps at all, but what a stupid place to try and save money!

Click to expand...

Have you priced a new 1747-L553 lately?

Based on the OP last post, 16K is more than plenty.

OkiePC said:

Have you priced a new 1747-L553 lately?

Click to expand...

Almost every customer I know first checks eBay.


A good 1747-L553 can be gotten starting at $1050. L552's start at $550