Problems with Siemens MMC cards

RMA

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Sep 2004
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North of Hamburg, Germany
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I recently had to order a 4MB MMC card from Siemens in order to upgrade my 317-2 DP CPU to V2.1.3 Firmware. The card arrived a couple of days ago and after downloading the 20+ MB Hotfix 3 for Step7 V5.2, (which was on the only PC we can run the prommer on, 'cause somebody's lost the prommer S/W!), from the Siemens website about five times before getting a copy that my various ZIP programs would accept (no error messages of any sort during the downloads), I downloaded the new firmware to the MMC, packed it in the slot in the CPU and powered up. Two minutes later I had an upgraded CPU.

So then I decided to copy my project to the new MMC - it had just outgrown the old 128kB card a few weeks before - and that kept me busy for a day and a half, before I decided that I probably hadn't suffered a dose of premature senile decay and sent an e-mail to Siemens before going off home. Barely back in the office this morning and the phone rings with the Siemens hotline on the other end. So I tell him the story, explaining everything I've tried, "The card's probably faulty" he says, not sounding very surprised. "But the firmware upgrade worked fine" I said. "Doesn't matter - email me the contents of the diagnostic buffer".

No sooner said than done. I had barely had enough time to move back from the Internet PC to the project PC before the phone rang - "Card's faulty, send it back."

I don't know whether this problem only affects the new range of MMC cards with the part number 6ES7 953-8Lx11-0AA0 (where "x" denotes the memory size) which also have the problem with Step7 V5.2. But the message is - if you have funny problems with a Siemens MMC card - don't waste your time trying to suss out what you're doing wrong, get straight onto the Siemens hotline. banghead
 
New Twist!

I just called the Siemens "Retour-Centre" to find out what the procedure is for returning the faulty MMC card and getting a new one in exchange. As expected no great problem.

"Just send us the old card back, we'll send you a new one then repair the old one and put it back in stock". Ehhh!!!
 
"Repairing" probably means "reformatting the MMC card with the special Siemens disk format".

Could it be that we dont have a "Format MMC card" utility, because that would mean we could turn any commercial MMC card into an S7 compatible MMC card ?

By the way, I am impressed how you keep up your morale with all these problems you have with FM's and MMC's.
 
By the way, I am impressed how you keep up your morale with all these problems you have with FM's and MMC's.

I'm in the position of enjoying the absolute luxury (which I have never experienced before and probably never will again) of having absolutely no time pressure. Because of very long delivery times for most of the hardware(which is all made to order one-offs), I can take my time. On top of that, the actual control aspect is relatively simple in principle, even if the quantity is fairly significant.

So all in all it's an ideal opportunity to learn about S7 to a level which I haven't been able to on previous projects. They were either very simple, or if they were more complex (such as the 8 MW Turbine control project I was involved with a couple of years back), then I was only one of a team and they always threw the HMI at me, because with my DCS/SCADA background that's one area where I'm completely at home.

The only slight problem is that I'm here as a sub-contractor and nobody else in the company has a clue about PLCs, so I'm the expert! And there's nobody at hand to ask, so if I hadn't found this forum, my morale might not be quite so good!

As we get nearer to shipping the first module the pressure will start to increase, but we're not there yet and the FMs are the last thing I've got to get a grip on (apart from the logging, but I can take my time on that a bit, as long as everything is actually working). We should be shipping middle of November, but I've a feeling that's going to slip. :D

So for the time being I'm still having a ball!

Edit: I suspect that the problems with the MMC cards are probably caused by Siemens encrypting their formatting somehow, in order to prevent a simple Bit by Bit read out and copy to a normal MMC card. Looks like they haven't quite got a grip on it yet, though!
 
Last edited:
Hi,

If Siemens provide such tool we all could use cheap MMCs with Siemens CPUs.

By the way, with VIPA CPUs you can do that: buy one MMC in any shop, format it in your PC (FAT16) and use it. Buwith VIPA CPUs you only need MMCs if you need to store data files because all load and work memore are already integrated in the CPU.
 
Fox said:
Buwith VIPA CPUs you only need MMCs if you need to store data files because all load and work memore are already integrated in the CPU.
As I understand, MMC in VIPA is used to store some data even if power is off. To access this data there are SFCs 220, 221, 222. But to access this data from PLC we should know the name of the file on MMC. Where should we store this filename then?

Or are there any other possibilities to store data when the power is off without using MMC?

Thanks in advance
 
RMA said:
I just called the Siemens "Retour-Centre" to find out what the procedure is for returning the faulty MMC card and getting a new one in exchange. As expected no great problem.

"Just send us the old card back, we'll send you a new one then repair the old one and put it back in stock". Ehhh!!!

You can repair it yorself. Look at here
http://www.plctalk.net/qanda/showthread.php?p=163950#post163950

BTW, I still looking for 2MB MMC image.
 
MMC faulty happens all the time. I have many experiences with it. So nowadays my fellow engineers and I carry a spare tested working MMC wherever I go.
 
Schtiel said:
As I understand, MMC in VIPA is used to store some data even if power is off. To access this data there are SFCs 220, 221, 222. But to access this data from PLC we should know the name of the file on MMC. Where should we store this filename then?

Or are there any other possibilities to store data when the power is off without using MMC?
What Fox meant to say is that VIPA works in the "traditional" way. The memory has battery backup, so a flash storage is not ultimately necessary.
The newer Siemens S7-300, on the other hand, must have an MMC flash storage as it is used for power down backup.

Both Siemens and VIPA have special function blocks to write to the flash storage from the program. But that is another topic.
 

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