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Old February 29th, 2008, 03:56 AM   #1
uptown47
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Memory Reset not working Siemens PLC

Hi all,

Correct me if I'm wrong but if I hold down the MRES switch on a Siemens 300 series PLC and wait until the amber light stops flashing, then release the switch and hold it down again quickly (causing the amber light to blink rapidly) then this should reset the memory?

This doesn't seem to be working on two different 313C PLC's. I do an "overall reset" but when I interrogate the PLC the program blocks (eg. FC1, FC2 etc) are still in there?

Does the overall reset not clear these out or are they held somewhere that's not being erased?
How do I quickly erase these blocks?

Many thanks

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Old February 29th, 2008, 04:03 AM   #2
Bratt
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The memory reset does not clear blocks that are located on the MMC card. It only clears the plc and the blocks are then loaded back to plc. If you have a Siemens FieldPG or an external Siemens prommer you can erase the card offline in Step 7. Another way is to use image files and tools from this site then you can use any card reader. Search for MMC on this forum and you will get more help.

Last edited by Bratt; February 29th, 2008 at 04:07 AM.
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Old February 29th, 2008, 04:05 AM   #3
uptown47
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How do I clear the MMC then?

Can that be done through the MRES switch or is there a menu command through Simatic Manager?

Thanks

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Old February 29th, 2008, 04:08 AM   #4
Bratt
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You can go online in step 7 and select the blocks you want to delete but not all attributes are deleted this way. To delete all the only way is an external reader.
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Old February 29th, 2008, 07:32 AM   #5
JohnW
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You can clear all data from an MMC card like this:



Instructions:
It is not possible for users to format an MMC. All you can do is "reset" an MMC, which deletes all user data. Proceed as follows.
  1. The MMC is slotted in the bay of the CPU. Your CPU requests an overall reset (slow blinking of the STOP LED).
  2. Set the switch to MRES and hold it there (approx. 9 seconds) until the STOP LED lights continuously.
  3. Within the next 3 seconds you must let the switch go and set it again to MRES. The STOP LED now blinks during the delete procedure.

If the MMC continues to request an overall reset after the procedure described above, then it is defective. Note:
It is only possible to reset the MMC if it contains data that is invalid for the CPU. Otherwise the MMC is only initialized by the procedure described.
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Old February 29th, 2008, 07:50 AM   #6
Bratt
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Quote:
Originally Posted by JohnW
Note:
It is only possible to reset the MMC if it contains data that is invalid for the CPU. Otherwise the MMC is only initialized by the procedure described.
But then you need to put your mmc in another diffrent cpu or? Do you know if this procedure deletes the Saftey attribute for F-Cpus aswell?

Last edited by Bratt; February 29th, 2008 at 07:52 AM.
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Old February 29th, 2008, 07:53 AM   #7
uptown47
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That would confirm my experiments... 2 PLC's, if I swap the MMC's then they request a reset (ie. blink the amber light). When I do the reset it clears the MMC completely.

However, doing a reset to an MMC that has the correct PLC info on doesn't clear any of the blocks..

So, it seems the only way to clear an MMC is to do it online via Simatic Manager.

Thanks for all your help. Much appreciated.

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Old October 20th, 2009, 09:18 AM   #8
budahab
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my s7 313c is stop led flashing evry time and i there is no connection between the plc and pc is the diffrent version is effecting and i made rest memory by mrs and main but is not going well flashing stop led
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