S7300 CPU Swap - Datablock Values advice

STL???

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Join Date
Sep 2005
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Hi everyone,
I need to change an old 316-2DP processor for a 317,I've been investigating for the last few days the best method in which i can restore the online DB Data from the 316 to the replacement 317 after installation.

My usual method is to blockmove all presets in ob100 on start,however in this case all process data even in instance DB's is wrote from a PC.

To add to my woes the PC application is no more, basically it's a custom VB project with a runtime licence tied to the hard disk which has failed, We never had the project file and the company went under last year. We restored an image to a replacement harddisk but its a no go.

I will be replacing this with WinCC Flexible 2008, however the only window i have to change the CPU is this week.

Looking at these old threads:
http://www.plctalk.net/qanda/showthread.php?t=31326
http://www.plctalk.net/qanda/showthread.php?t=47108&highlight=datablock+values
http://www.plctalk.net/qanda/showthread.php?t=39685&highlight=datablock+values

If i did highlight the DB's online and uploaded to pg,would this guarantee correct values in the new cpu once downloaded?

My other option is Wincc Flex storage scripts for each DB, but that would be time consuming so a quicker route would be preferable.


Thanks in advance for any help
Steve
 
If i did highlight the DB's online and uploaded to pg,would this guarantee correct values in the new cpu once downloaded?
This should be possible, but to my experience, most often the timestamp does not match, so the symbol declarations are lost. Give it a try.
My other option is Wincc Flex storage scripts for each DB, but that would be time consuming so a quicker route would be preferable.
I do that. It is very handy for safeguarding the DB contents when updating the PLC program. And for a number of other reasons.
I would make such a save/restore function even if the upload did work.
 
DB Save/Restore Scripts

Hi Jesper,
I downloaded your sample project from the download area and was wondering how you got the values 100 & 200 for 25(DB1)/40(DB2) words declared?

Thanks Steve
 
Hi Steve.

You must be referring to the strXYarray.
I sure hate to go back to old code. especially when I havent documented it perfectly.
I think that I have just reserved enough array lines to not have to worry about the size. Otherwise, it must be hardcoded for each DB.

I have to admit that today I have reverted to saving and restoring by means of the individual tag names, rather than en masse.
So it looks in my save files like this:
Mix.Factor_1 ; 13.22
Mix.Factor_2 ; 15.01
Mix.Dose_Min ; 3.5
Mix.Dose_Max ; 10.5
Disch.T_set ; 300
Disch.T_limit ; 1000
etc.
This means I havent tested the older script es extensively as I normally do.
 
Hi Jesper,
You must be referring to the strXYarray.
Sorry - yes, i thought i'd wrote that in the post, asking questions whilst i'm tired (4am)is no good.

Testing using WinCC Flex & PLCSIM works fine with smaller DB's,but on larger DB's (which are well within the 2000 word limit) i get a overflow message even though the script executes the transfer successfully?

I think i will update to the Hotfix, because i cant get ShowSystemAlarm,ShowOperatorNotes to work in either scripts or triggered by button.

5 years on and this software still has issues!
 
Last edited:
Maybe it has something to do with the 244 byte limit that can be handled in one communication instance of most CPUs ?

You can try to cut it down into several array tags, each smaller than the 244 bytes.
 

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