Siemens S7 200 Data restore after long power down.

sonarbell · Nov 3, 2009

Hi All
I use 200 processors on a regular basis and sometimes during long power downs, Xmas etc the CPU has a nasty habit of forgetting the data in its head..

If I add the following in OB1 will it restore the default values I have written in the "move" commands ?

These values will get the machine back up and running after which time the customer can change the values to there own settings via the display.

Or does anyone have any other ideas.

Cheers Chaps

bkottaras · Nov 3, 2009

sonarbell said:
Hi All
I use 200 processors on a regular basis and sometimes during long power downs, Xmas etc the CPU has a nasty habit of forgetting the data in its head..

If I add the following in OB1 will it restore the default values I have written in the "move" commands ?

These values will get the machine back up and running after which time the customer can change the values to there own settings via the display.

Or does anyone have any other ideas.

Cheers Chaps

Since the 200 series uses a super capacitor as a battery, after a long period of being powered down it just loses the PLC program.
Are you sure the program stays and you just lose settings as shown or do you have to download the program and set it to run prior to running?
If the program is there after power up and you use the MOV during the first scan to load the parameters to the registers, you'll be OK.

sonarbell · Nov 3, 2009

The Prog is there but the data is lost. The Super Capacitor is only used for backing up the status of the bits in the processor.
The Prog is loaded from EEPROM should the initial scan show that the data area is empty.

I think that SM0.2 is a bit that is set for the initial scan should the PLC decide that the memory area is at zero. I hope this makes some sort of sense.

What is so frustrating is that I cant store the customers own settings anywhere and reload should the memory be empty.

Hey ho its only a cheap processor when all said and done.

BryanG · Nov 4, 2009

Put a battery in it and it will store the data for over six months without external power. Whats more the battery is only used after the super capacitor has discharged and so can last as long as its shelf life of 7 years (ish). The program in the PLC is stored in eeprom and so doesn't get lost after a loss of power. All this assumes you are talking S7-224 to 226.

Bryan

sonarbell · Nov 4, 2009

Thanks Bryan.

Pego · Nov 4, 2009

You can also use the write to eeprom function, SMB31 en SMW32 to store your variables pemanently.

HAROLD · Nov 4, 2009

You could also try "Create Data Block From RAM"
This is done with STEP 7-Micro/WIN using the main menu "PLC"

Pego · Nov 4, 2009

HAROLD said:
You could also try "Create Data Block From RAM"
This is done with STEP 7-Micro/WIN using the main menu "PLC"

sonarbell said:
after which time the customer can change the values to there own settings via the display.

What sonarbell wants it to keep customer values after a longer period of power down and not reprogram the PLC.
Customer value can be saved permanently by the PLC program by writing them to eeprom directly after entering.

sonarbell · Nov 5, 2009

Hmm very interesting the point about writing it to eeprom..Didnt spot this before so will research and see how we go..

Thanks for that piece of info PEGO

pakratt · Mar 15, 2011

You may want to check into recipes.Plug a data module into the s7200 and add a recipe to your program.Using the recipe wizard.You can read your values into your program.You can also write your adjusted values out before long shutdown periods.

Jeff23spl · Mar 16, 2011

What about powering the plc separately so never cut it down during holiday?

You can copy the customer data in your data block and write them in the rom memory so it will takes these values after a long poweroutage but it's the same as doing a save to eeprom...
The save to eeproom block need to have an data block range and a pulse input to work. I include a buton on a hmi page to sava any setting that a customer may have done at startup or latter...
But i also try to get rid of that bad habbit to cut power off from plc when they stop the factory....ok to cut MCC power from motor but from plc is not usefull and may gives problems like that....

Siemens S7 200 Data restore after long power down.

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