7/22/2020 2:49 PM | |
Joined: 9/27/2006 Last visit: 10/17/2024 Posts: 12289 Rating: (2687)
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Hello Nadjim; The battery (depending on the power supply model, there can be one or 2 of them) are used to maintain the PLC program that is in RAM (load) memory. The S7-400 has 2 main memory areas (as seen by the programmer, Load memory, where the program blocks are downloaded and uploaded, and Work Memory, where the program is executed. Look at this description for more details: How can I get an overview of the S7-400 memory concept? https://support.industry.siemens.com/cs/ww/en/view/7302549 The following points determine the decision on which memory card to use: Do you wish to retain the user program on the memory card when the power is OFF and without a back-up battery? If so, this would necessitate the use of a flash memory card. Warning: If you use a flash memory card without back-up batteries, the blocks in the RAM part of the load memory and the data (main memory and system memory) will be lost when the power is OFF. Do you wish to be able to change the user program in RUN mode, and is the program too big for the internal RAM? If so, this would necessitate the use of a RAM memory card. When using a RAM memory card, the system must be battery-operated so as to back up the RAM memory card data and the data in the internal RAM if there is a power failure. All S7-400 CPUs have a small section (generally 256 kB) of RAM memory onboard, so you can always download a basic hardware configuration, and this section must have battery support, even if you choose an EPROM card that dowes not require a battery. Here you will find information on the S7 batteries so you can select them for replacement: Where can you find information about the S7-200/S7-300/S7-400 backup batteries? https://support.industry.siemens.com/cs/ww/en/view/12067424 Hope this helps, Daniel Chartier |
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