8/22/2013 12:41 PM | |
Joined: 4/22/2010 Last visit: 5/3/2024 Posts: 5697 Rating:
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Hello,. Please don't mix up MMC (for 300 CPU) and Flash/Ram- cards. How can I get an overview of the S7-400 memory concept? This FAQ, will answer most of your questions, if still in doubt about any part of this FAQ, please return. Regards, Marcjan |
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8/22/2013 1:49 PM | |
Joined: 1/3/2006 Last visit: 2/19/2024 Posts: 726 Rating:
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Yes MMC
Yes
You don't hace access to PLC internal memory (Working memory). You have access to only Load memory. So everything is stored in Load Memory. Work memory can't be increased where as Load memory can be increased using (MMC, RAM, EPROM) In 400 there are two kinds of Load Memory
There is no MMC here ! In a given 400 system you can either use RAM or EPROM in a given slot of CPU. If RAM is used no special method required to save program but in case of EPROM you have to choose "Load user program to memory card" option. RAM needs battery to save your program while EPROM does not requires it. Always think Load Memory as hard disk of your PC, and Work Memory as RAM of PC. Programs are saved in Hard Drive (Load Memory) and OS decide how much of RAM (Work Memory) is to be alloted when it is made to run. Now if you program is so big that it required more RAM(Work Memory) then installed capacity, you have to buy a PC (PLC) with more RAM (Work Memory) ! Simple ! Regards, Manmeet. |
Last edited by: manmeet at: 8/22/2013 1:54 PM |
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8/22/2013 6:31 PM | |
Joined: 9/2/2012 Last visit: 8/15/2024 Posts: 711 Rating:
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Dear Manmeet, thank you for the reply.. I agree.. regarding, ·If my program size is greater than internal memory of CPU, am using FLASH card. And using normal download option, will it get download properly? ** ?? In the case of backup batteries(400 system), is it giving backup supply to PLC Internal memory also ( I mean to both the RAM card and PLC internal mem) ? ** ?? regards vipz |
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8/22/2013 6:59 PM | |
Joined: 4/22/2010 Last visit: 5/3/2024 Posts: 5697 Rating:
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Hello, 1st : if the program is bigger than the load memory it will not be downloaded correctly. 2nd: yes battery supplies both cpu ram and external ram-card. Regards, Marcjan
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8/22/2013 7:10 PM | |
Joined: 9/2/2012 Last visit: 8/15/2024 Posts: 711 Rating:
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Dear Both, in s7 400 also, retentive memory is inside RAM/FLASH card ?? in s7 400, we can use plc without LOAD MEMORY (WITHOUT RAM,FLASH CARD) provided program size is small . correct ? in that case retentivity will work if am providing buffer battery ?? regards vipz
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8/23/2013 6:10 AM | |
Joined: 1/3/2006 Last visit: 2/19/2024 Posts: 726 Rating:
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Yes
Your prgram goes in Load Memory and you need it for any downloaing to take place. You can just do some configuration changes in hardware to optimize the usage of work memory.
Yes Also follwong are few lines which I have taken from Simatic Manager Help. Just copy paste "Retentive Memory Areas on S7-400 CPUs" for more details.
Regards Manmeet |
Last edited by: manmeet at: 8/23/2013 6:11 AM |
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8/23/2013 7:21 AM | |
Joined: 9/2/2012 Last visit: 8/15/2024 Posts: 711 Rating:
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Deat Manmeet, some points are not clear to me.. 1. in s7 400 can we use PLC without any load memory?? consider my test program is very small compared to plc memory. 2. if am using plc without load memory, but providing buffer battery, retentivity will happen ?? 3. if am using FLASH card without battery backup, retentivity will work ?? regards vipz
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8/23/2013 7:42 AM | |
Joined: 4/22/2010 Last visit: 5/3/2024 Posts: 5697 Rating:
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Hello, 1. Load memory of the 400 system is the Internal Ram or External Ramcard/Flash, picture From the load memory the programblocks are loaded into the (internal) Work memory. 2. yes if you have backup battery the Retentivity will last as long as your battery is o.k.. 3. No. after power on the program is loaded from flash to work memory, all data blocks will use initial values. Without battery the work memory and the internal Ram is cleared. Regards, Marcjan |
Last edited by: Marcjan at: 8/23/2013 7:43 AMProblem solved? |
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