1/23/2015 5:14 PM | |
Joined: 4/22/2010 Last visit: 5/3/2024 Posts: 5697 Rating:
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Hello, Lets have a look at this picture: S7-400 memory concept You can see that user program is loaded to Ram Load Memory area. From Load Memoryrelevant parts are loaded to Work Memory (is also Ram) Ram memory needs power to retain it's contents. So without batteries, Ram is cleared and both Load and Work memory is cleared. In the (not the older CPU) 300, the MMC is the load memory, a MMC can retain the contents without power. In case of power down the data marked as retentive will be writen to the MMC, there is a super capacitor in the CPU that gives just enough time to do so.(not Always true i experienced At power on these values are loaded again together with the user program. A 400 CPU can only write to Flash card in stop mode, so writing retentive data to Flash is not possible. In case of power down, flah cardand no batteries, the userprogram with the initial values are loaded to Ram again. Hope it's clear now, if not please return. Regards, Marcjan |
Last edited by: Marcjan at: 1/23/2015 5:21 PMProblem solved? |
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3/30/2016 9:42 AM | |
Joined: 8/21/2014 Last visit: 8/16/2024 Posts: 1006 Rating:
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New question published by IZ ALJABRE-JORDAN is split to a separate thread with the subject Changing the user program in RUN. Best regards |
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