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S7 Memory

Created by: barks at: 4/19/2011 10:30 AM (6 Replies)

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4/19/2011 10:30 AM	Rate (0)
barks Posts: 2 Rating: (0)	Hi All, I'll start with a quick hello from a new poster. I am trying to find information regarding the data storage used by the Siemens S7 processors. Is there some good information to read about this somewhere? As far as I can tell, themodel I have(a 314), has an internal Flash EEPROM and an External MMC memory card. Are there any other memories? How are these used by the processor? I wondered if the application was stored on the MMC card and the devices firmware on the internal Flash EEPROM? Thanks Tom
barks Posts: 2 Rating: (0)
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4/19/2011 11:12 AM	Rate (1)
KayBee Posts: 241 Rating: (7)	Hi, Barks See the links following. This may help you find detail. S7 400 Memory S7 300 Memory Card What is load, work memory
KayBee Posts: 241 Rating: (7)
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This contribution was helpful to 1 thankful Users Cagri Yagmur (TR)

5/27/2011 8:39 AM	Rate (0)
aikona Posts: 487 Rating: (36)	Hi The JPG is a screenshot from two PLC's memory information You can get the same simatic manager if you goto the blocks of the CPU then right click , goto PLC then Module information and on the tab select memory .Press help to get info on the memory Basicaly you have three type of memory : One is the ,lets call it the storage memory , then when you start you PLC you have some memory reserved for your code and then a third memory for the data like datablock , local data etc. Eric Attachment plcmem.jpg (578 Downloads)
aikona Posts: 487 Rating: (36)
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5/27/2011 12:33 PM	Rate (0)
gre_m Posts: 947 Rating: (45)	Hello for Cpu s7-3xx exist flash eprom card (old type CPU) and mmc card. MMC card is load memory. Without mmc card CPU not work. In S7-300 can install only SIEMENS mmc-card. mmc-card other producer not work. Not Formated ithe mmc card under Windows!
gre_m Posts: 947 Rating: (45)	Last edited by: gre_m at: 5/27/2011 3:21 PM
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6/2/2011 1:41 AM	Rate (1)
woisi Posts: 21 Rating: (3)	Hello, only for information, if you have older S7-300-Systems (that one with the "great" EEPROMs->FLASH-Cards) the memory cannot be expanded (also not with RAM). The slot for the Flash-Card is only for the backup if the power get lost and the battery is empty or not in. If you have the newer S7-300 (with the "smaller" EEPROMs->MMCs) the size of the MMC ist the size of the LOAD-memory. The WORK-memory cannot be expanded, if this is full you only can select the next bigger CPU (of course you can try to reduce the size of the program: change the programm, get the spare out of the DBs,...pfff) It is similar with the S7-400 CPUs (but there only "great" FLASH-Cards and "great" RAMs are availabe - thay makes only sense in a S7-400). You can expand the internal work-memory with an RAM if nessecary. But be carfull if you will change it with an FLASH. The best ist to make a backup from the CPU so you have all actual datas, because you have to make an overall-reset if you change the cards, and all data will be lost. Then you can change the RAM with the EPROM (make the overall-rest) and load the backup into the FLASH. So now you have a empty RAM with you can use for the next changes, but dont forget to back it up again and load it to the flash (otherwise the changed, new program in the RAM will be lost if the voltage is lost and the battery is empty). The big advantage of the MMC (with can be very big to the internal working-memory, up to 8MB until now) is, that you can use the MMC for "unlinked" DBs. eg: for a lot of DBs for recipes, and only the used one is copied to the smaller work-memory (you have to to this in the program with system-functions) The disadvantage is - of course - the bigger price. Hope there is no mistake and I could help a little !
woisi Posts: 21 Rating: (3)
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This contribution was helpful to 1 thankful Users IBN-Service

6/2/2011 12:26 PM	Rate (0)
gre_m Posts: 947 Rating: (45)	Each cpu has load and work Memory. (I can nottell youaboutthe oldCPU,Ido not know muchof their(I'mnotsure)). CPU 3xx not have internal load memory. For Load memory used MMC-card. CPU4xx have internal load memory(256Kb as default, depended from MLFB). As Flash CPU 4xx use great flash card. This card can only full overwrite. In MMC card - you can write 1 block. Great RAM card for CPU4xx use for extend LOAD ram, NOT WORK RAM! Work memory in CPU not expandably.
gre_m Posts: 947 Rating: (45)
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7/11/2014 3:19 PM	Rate (0)
Narrator1 Bronze Member Joined: 3/25/2013 Last visit: 3/21/2019 Posts: 176 Rating: (1)	New question split intoHow to reduse load memory usage in CPU?. With best regards, Narrator1

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