Siemens 317F-2 PN/DP - MMC Defective?

Today I ran into the following problem with a Siemens 317F-2 PN/DP CPU running Firmware Version 2.6.0.

The setup was as follows:
1. ET200S remote I/O connected to ProfiNet via IM 151-3 PN HF
2. Programming Computer running Step 7 V5.4 SP3 connected to CPU via Profinet.
3. All ProfiNet devices connected to a dedicated Scalance X108 switch.

I was monitoring a few of the remote inputs via a variable table when first the power to one of the ET200S was interrupted and then the PLC power was turned off as well. After turning power back on the CPU went into "Panic" mode with all LEDs flashing. The only way I was able to get communication with the PLC was to remove the micro memory card and reassign the PLC IP address. Evaluation of the Diagnostic Buffer (see attachment) indicated that the CPU detected an "Internal System Error" (Event 5) followed by a "Illegal memory submodule: replace submodule and reset memory" (Event 4). I tried resetting the memory module multiple times with no success.

I have contacted our local Siemens distributor and ordered a new MMC but am wondering if anybody here has had a similar experience and has some advise as to what may have caused this error.

Thank you,
Felix

Siemens had a problem about two to three years back with a new range of MMCs with part number 8Lx11... As I understand it they had modified the formatting to make them more resistant to copying. For whatever reason, these went down like flies, but the problem was well known to Siemens and when I phoned them up about a dead MMC the answer was "send it back, we'll send you a new one and repair(!) the old one and put it back in stock".

Both the CPU and the MMC are less than 6 month old. At the moment I suspect that the problem I have results from the fact that power to the CPU was turned off with an active variable table. I am not sure that the ProfiNet connections had anything to do with the problem I am seeing. However, I do remember cases in the past where a loss of ProfiNet communications resulted in a corrupted MMC.

This machine is used for R&D and there will be plenty of programming changes so I really want to get a good feel for why this is happening and besides, ~$300 per programming change for a new MMC is not really acceptable to our customers. Once I receive my replacement MMC I will first update the CPU firmware and then try to reproduce this error. I will report back when I know more...


Regards,
Felix

Do you have very long ethernet cables ?
Maybe you have a problem with ground voltage differentials between the ends of the ethernet cable.
When you say "I do remember cases in the past where a loss of ProfiNet communications resulted in a corrupted MMC", what did Siemens have to say about that ?

Jesper,

the longest ethernet cable is about 45ft/14m. I am not sure if this would be long enough to cause significant ground voltage differences at the ends of the ethernet cable...

In regards to loss of ethernet communication causing a corrupted MMC let me clarify that this only happened while downloading programs to the CPU and that this problem was resolved by a firmware upgrade. At the time I was experimenting with using wireless networks for both process network and connection to the programming computer. Since this was over a year ago I will need to go back to my notes for details. Anyway, I would like to believe that this issue has been resolved in all recent firmware versions.

Regards,
Felix

There goes another one...

I did get a replacement MMC this morning and updated the CPU firmware to version 2.6.5. After verifying that the firmware upgrade was successful I went to download my program to the CPU. With the download at about 90% completion the CPU went into Panic Mode again. The diagnostic buffer shows the same error code (Z1=914a).

I just sent my diagnostic buffer to Siemens and will let you know what they have to tell me...

Regards,
Felix

I think that some of the blocks gets corrupted on the path from your PC to the MMC card. It could be noise, bad cable, bad connectors or something completely different.

Do you know this tool that should enable you to take a snapshot of the MMC card ?:
http://personal.telefonica.terra.es/web/suwe
If you have fresh empty MMC card, you can take an image.
If another download goes bad, you can then try to restore the image.

Notice: Do not format the MMC card in your PCs card reader !

I have almost the same problem few times already on that same CPU.

Siemens suggested replacing MMC but it looks like erasing them with promer does the trick, at least in my case...

If you dare, then you can try the latest firmware which is now at v2.6.5:
http://support.automation.siemens.com/WW/view/en/23876037

Jesper,

I will try the MMC snapshot tomorrow since currently I am again waiting for a replacement MMC. Seems like this tool is exactly what I need to troubleshoot this kind of problem. Thank you very much for the tip!

I already have updated my CPU firmware to version 2.6.5 which unfortunately did not solve the problem. The Siemens guy I talked to said that the problem might be related to the fact that I am running Step7 V5.4 SP3 without HF1. He also made me update S7 Distributed Safety to V5.4 SP4 (I was running SP3) before. I am not sure if this had anything to do with my problem but I guess that its Siemens policy to have you update your software to the latest versions before really starting to troubleshoot the problem.

Panic Mode,

unfortunately I don't have a Siemens Prommer available at the moment. If the program Jesper recommended won't do the trick I will order one...

Thank you,
Felix