Schneider Unity Pro - PLC vs Local Init Values & Current Tag Values

Hi All,

Can anyone explain to me:

1) What are 'PLC initialisation values",
2) What are 'Local initialisation values', and
3) Why I am getting a warning in unity pro 'the initialisation values in the PLC are different from those of the local application (see link below):

http://imgur.com/a/lH9fSZF

According to the link below:

https://www.schneider-electric.com/en/faqs/FA197405/

The tags with 'save' checked are the ones that are saved in the offline program when 'update initial values with current values' is performed.

So, are 'PLC initialisation values' simply the current tag values for 'SAVE' tags and are 'Local initialisation values' the data stored in the offline program for these tags?

Why do they have to make this so difficult to understand? A PLC is a PLC, every PLC I have used (Siemens, Rockwell) it's easy and essential to upload the current tag values into the backup. Why is this so hard for me to understand?

Thankyou!

Do you have unlocated or located variables with %MW adresses?

Hey there

I am not sure what a 'located' variable is.

%MW addresses are being used in the program - they are declared in the elementary variables hence they have tag names, etc.

Thanks for your reply.

unlocated variable is variable which have only symbol name, no any address (communication can be via Schneider OPC driver)

Located variable have %M or %MW addressing

Save attribute is only needed with unlocated variables.
%M and %MW address range is automatically backed up.
There is setting on PLC properties if %MW data is zeroed on CPU cold start.

If you uncheck that, then CPU will allways remember %MW data areas and only %M addresses are zeroed.

On Warm restart both %M and %MW area keep data


If unlocated areas aren't used to setpoints, then you can uncheck save attribute also from unlocated data.

For located data save attribute isn't needed.


%M and %MW areas can be also saved (readed) to *.dat or *.DTX files.
Then when you load Full PLC program to new CPU, you can load also data from *.dat or *.DTX files.

Downloading full program to old CPU not necessary change old data (%MW) from CPU, but it depends of CPU properties you have on projects.
Also *.dat files are needed, if your PLC brokes.

Thanks very much for your detailed response. I think I am getting closer to understanding.

Can you explain to me in simple terms what 'update initial values with current values' and 'update local init values with PLC init values' means?

https://www.se.com/in/en/faqs/FA197511/


'update initial values with current values'
- PLC saves values to memory, so after cold start data is restored to init values.

There is also system bit on PLC and you can make this save automatic on PLC code.





'update local init values with PLC init values'
- init values is moved to your offline project from PLC memory. If you look variable value colum on offline, you have same data that you see on variables at online.


Since you use %MW addressing, save attribute is maybe not needed.
But with init values you can save bits (which you can also without save attribute) and init values on cold start (which can done on code, if init values isn't used)