11/19/2010 8:07 PM | |
Joined: 9/27/2006 Last visit: 9/10/2024 Posts: 12282 Rating: (2682)
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Hello ameic; What exactly is the part number (MLFB) of your CPU? Older models of the CPU 315-2 used a RAM or EPROM card as load memory, with battery backup; the newer ones use MMC cards, which are based on NFLASH technology, as load memory, and do not have a battery slot for backup protection. So the question does have its importance. If you have a newer CPU with an MMC card, load memory is totally dependant on the MMC card, so you cannot load your program to a defective or already programmed MMC card. But comms will be maintained as it was on the previously downloaded configuration. I would suggest that you read the chapter on MMC memory (chapter 4) in this small document. I have exracted a few comments that might interest you: http://support.automation.siemens.com/WW/view/en/7302326 Storage Concepts for SIMATIC S7-300 CPUs and for C7 Devices [Extracts from chapter 4: CPUs with MMC slot] Depending on the CPU operation from the memory card (MC or MMC) Loading of user programs, hence operation of the CPU, is only possible in conjunction with a SIMATIC Micro Memory Card (MMC). If I were to venture a guess, based on the description of your problem, I would think that the MMC in question has either been used on a different project orCPU before; it could also be that it has been formatted in a standard card reader (and has therefore had its Siemens formatting overwritten) or that it is defective, You could try the solution proposed in this FAQ and see if it will fix your problem: How do you reset a SIMATIC S7-300 CPU and MMC (default reset or overall reset)?
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Last edited by: dchartier at: 11/19/2010 8:11 PM |
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11/20/2010 4:18 PM | |
Joined: 9/27/2006 Last visit: 9/10/2024 Posts: 12282 Rating: (2682)
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Hello ameic; Even if you had properly downloaded the program to the CPU with a properly formatted MMC before, the CPU will not run withour a MMC (load memory) slotted in its local. Now, once the MMC has been formatted oputside Siemens' recommended hardware, it is very difficult to re-format it. I have seen threads elsewhere that discuss the issue, even some sites that propose Siemens images for MMCs, but the correct implementation is not easy, The following FAQ will give you Siemens' point of view on the subject. Why is the SIMATIC MMC not read in my card reader (third-party device)? It would be simpler to just get a new MMC for your application. Hope this helps, Daniel Chartier |
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