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Difference in RAM card and memory card FEPROM for CPUs S7-400 family.
Created by: Andersonlink at: 9/30/2013 7:33 PM (11 Replies)
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| 9/30/2013 7:33 PM | |
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Posts: 5 Rating:
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Good afternoon, I wonder the difference in RAM card and memory card FEPROM for CPUs S7-400 family. And its application. Thank you. Sincerely, Anderson de Souza |
| 9/30/2013 8:39 PM | |
Joined: 9/27/2006 Last visit: 10/10/2024 Posts: 12286 Rating:
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HelloAnderson; Both RAM and FEPROM cards are supoorts for the Load memory of the S7-400. The RAM card supplements the existing RAM in the CPU, and needs to be backed-up by battery power: no battery means the program will be lost when you lose the PLC's power supply. When you download your program blocksto the CPU, it automatically starts using the integrated RAM, then the RAM card inserted in the MC slot. If you have a FEPROM card in the MC slot instead of the RAM, you must force the write operation ("Copy RAM to ROM" operation) everytime you want to save the program to the CPU, and the CPU must be in Stop mode.In case of restart of the CPU, it will read the contents of the FEPROM card, even though there might be no battery. Note than any ROM card has a limited number of write operations that can be performed during its lifetime. In our S7-400 projects, we would oftten use a RAM card during the programming and commissioning stages, when we have to download changes to the PLC program quite often. When the project was finished and we were relatively certain of our program, we would replace the RAM with an FEPROM card, write the program to ROM, which would make unintentional saves to the program more difficult. Follow this link to have an official explanation of the differences between RAM and FEPROM of the load memory: How can I get an overview of the S7-400 memory concept? Hope this helps, Daniel Chartier |
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| 9/30/2013 9:13 PM | |
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Posts: 5 Rating:
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Thanks, your answer was exactly what I needed to clarify my doubt. Even more. Anderson de Souza |
| 10/2/2013 7:38 PM | |
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Joined: 9/27/2006 Last visit: 10/10/2024 Posts: 12286 Rating:
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Hello vipz, Anderson; Vipz is quite right, I had forgotten that the S7-400 has a different function to write to the FEPROM card. Apologies for a faulty memory. It is timeI get back on a S7-400 project, it seems.... Here is a FAQ explaining how to copy the program to a FEPROM card on the S7-400: How can you write the program to the FLASH Memory Card when using a SIMATIC S7-400 CPU? Hope this helps, Daniel chartier |
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| 3/17/2015 1:38 PM | |
Joined: 1/15/2015 Last visit: 3/22/2022 Posts: 66 Rating:
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Dear experts am Jabre from Jordan, actually am still new here so let me say hello to all may i ask in which situations the CPU goes to stop mode if i want to do downloading?
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Last edited by: ALJARE IZ at: 3/17/2015 1:40:12 PMLast edited by: ALJARE IZ at: 3/17/2015 1:46:21 PMLast edited by: ALJARE IZ at: 3/17/2015 3:01:19 PMLast edited by: ALJARE IZ at: 3/17/2015 4:31:40 PM |
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| 3/17/2015 6:26 PM | |
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Joined: 1/15/2015 Last visit: 3/22/2022 Posts: 66 Rating:
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Thank you MR.dchartier for this But am still Wondering, it's clearly written here Automation System S7-400, CPU Specifications in page 31 That i have to put the CPU in stop even it has a flash card
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Last edited by: ALJARE IZ at: 3/17/2015 6:39:13 PM |
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| 3/17/2015 8:29 PM | |
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Joined: 9/27/2006 Last visit: 10/10/2024 Posts: 12286 Rating:
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Hello Jabre; i think your doubt will resolve itself if you use the full name of a Flash card: it is knownn technically as a Flash-EPROM card. From Wikipédia: Although flash memory is technically a type of EEPROM, the term "EEPROM" is generally used to refer specifically to non-flash EEPROM which is erasable in small blocks, typically bytes.[citation needed] Because erase cycles are slow, the large block sizes used in flash memory erasing give it a significant speed advantage over non-flash EEPROM when writing large amounts of data. As of 2013[update], flash memory costs much less than byte-programmable EEPROM and has become the dominant memory type wherever a system requires a significant amount of non-volatile, solid-state storage. |
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