how to start work with CPU 315C-2DP and MMC

RMA

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Got this one by PM:

how to start work with CPU 315C-2DP and MMC.
CPU without MMC work good, but with MMC (8MB) - SF LED is lighting RED. I must format MMC, or special start procedure CPU? Help me please. Manual (link) or other.

PeterC

First thoughts are:

1) Can a 315C-DP really run without its MMC? (I only know the 315-2DP and it can't).
2) Is the MMC a genuine Siemens MMC? They have a special format and as far as I'm aware no one has yet found a way to format a normal MMC so that they can be used in a 300 Series CPU.
3) Can the 315C-DP handle an 8MB MMC. I don't have a catalogue to hand, but the data I have for an older 315-DP says that it can take an EPROM with max. 4 MB.
 
I do not have all the info and I know that everything depands from cpu to cpu so my thoughts...

1) if the cpu has a MMC-slot, it also must have the MMC because this is the load-memory for the cpu. In the loadmemory are; the user-program, DB's (linked and unlinked) systemdata (hardware-configuration). After restart; the user-program (but only a part of the program from the loadmemory), systemdata (HW-configuration) and linked DB's are copied to the workmemory.

2) Yes, siemens has its own format...although I have read that it is possible to 'copy' this format, I have never seen it done.

3)if you don't have a catalog use 'google' and search for 'siemens mall'. there you can find the info if the 8 MB is not too much.
 
You can get the processor to run (at least run led on ) , interestingly , if you drop the hardware config in without MMC , S7 states that it wasn't possible to download the SDB's , but it is possible then to restart the processor , however of course since there isn't any load memory , it isn't possible to do anything else .
So , in summary you do need an MMC , and the max pluggable for the latest revision processor is 8 Meg
 
Last edited:
OK even with an empty workmemory the cpu can be in RUN-mode. You can conclude that, on restart, the cpu does not detect that there is no loadmemory present and does not go in STOP-mode. It just runs on empty workmemory, wich is ram-memory.
 
RMA said:
3) Can the 315C-DP handle an 8MB MMC. I don't have a catalogue to hand, but the data I have for an older 315-DP says that it can take an EPROM with max. 4 MB.

The newer 315-2DP's can handle 8MB MMC's.

I didn't know that there was a 315C-DP, maybe it's a typo, and PeterC means a 313 or 314, anyway as ivo has stated, if the MMC card is clear the CPU can still be put into run mode without any system fault LED being lit, so I suspect that this MMC card has a previous configuration on it from another CPU. Perhaps Peter can confirm that this is a blank MMC.

If Peter has Simatic Manager, he can go online and interogate the CPU diagnostics and find out what is causing the SF LED to light.

Paul
 
Not so long ago i used a new cpu and a new MMC and if i remember this correct it worked (plc runned the program) without the HW-configuration.

Normally this should mean that also without a HW-configuration the cpu can start-up when the actual and expected HW-configuratioon is different. Normally the 'start-up'-behaviour is something what you define in the HW-config. Default is 'start-up when actual and expected HW-configuration differ'.

Later I tried to download the system data blocks because I programmed the clock memory byte in the HW-configuration of the cpu but I could not use the clock memory byte. I found this strange, downloaded it again with the some result. When I tried to upload from the plc to pc, I got an error because the HW-configuration did not recognise the cpu. This was because I had a different ordernumber then in the HW-configuration-folder. When I used the same type of cpu (but with a different partnumber) in the HW-config and dowloaded it, there was no error and the clock memory byte worked. But even without a selfmade HW-configuration the program worked fine.
 

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