support.automation.siemens.com | Technical Forum | Tuesday, September 16, 2025 7:02:16 PM

MMC card getting corrupted

Created by: Sree at: 12/22/2006 12:59 PM (1 Replies)

12/22/2006 12:59 PM	Rate (0)
Sree Posts: 7 Rating: (0)	Dear All I am facing the problem of MMC card getting corrupted often in S7-300 PLC. Please suggest any precautionary measures to avoid this issue. Regards Sree
Sree Posts: 7 Rating: (0)
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12/23/2006 12:32 PM	Rate (0)
Late Platinum Expert Joined: 1/7/2006 Last visit: 5/11/2025 Posts: 2705 Rating: (321)	Hi Sree, Never take out the MMC when the CPU is under power, first switch off power and then get out the MMC. Look to the power module, is it a powermodule thats from the PS307 range that fits for the CPU? Never use the same power for your internal and external 24V, only when you know that there are no possibility of strong inteference. Avoid low powers where the CPU is working on (<24V), when you switch off the power, the MMC is written with the actual values. Also look if there are SFC83/84 in use, this SFC's can WRITE on the MMC, when they doing this cyclic then are the writecycles of the MMC very fast reached (I believe you can write 100.000 times the MMC). [:o] I don't think you switched off the power that much... [;)]
	I hope that the answer will help, if you have still questions, don't hesitate to ask me. All the best, Late Never say never, think in solutions, not in trouble......
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