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| 10/16/2011 5:48 PM | |
Joined: 3/21/2006 Last visit: 9/10/2024 Posts: 10228 Rating:
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Rechargeable battery: If the CPU is operated without a back-up battery and you only wish to back up the time against power failures on CPUs with a hardware clock, you can insert a rechargeable battery in place of the back-up battery in the back-up battery compartment. In this case only the time is maintained. The RAM and RAM loading memory are not maintained in this case, so a memory card is absolutely essential. A limited number (CPU-specific) of bytes may also be maintained in a data block or by flags, timers and counters. If you insert the back-up battery (buffered CPU mode), the RAM, the RAM loading memory of the CPU and the clock are maintained even if power fails. In this case, all the data blocks and any flags, timers and counters defined in the parameter settings are also maintained. Why does the retentivity behavior of the S7-300 CPUs and C7 devices without MMC (Micro Memory Card) influence the contents of the variables? Best regards, Hristo Mihalev |
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