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When does retentive DB values reset to its default value?

Created by: G_R_E_Y_31 at: 5/7/2020 12:51 PM (1 Replies)

5/7/2020 12:51 PM	Rate (0)
G_R_E_Y_31 Bronze Member Joined: 5/26/2011 Last visit: 11/14/2024 Posts: 456 Rating: (7)	When exactly does "retentive" DB values reset back to default/start value in TIA Portal? This is called re-initialization right? There are downloads that requires DB re-initialization, but there are also download that does not. If I re-download a backup project, that would probably need DB re-initialization right? If the CPU broke and need replacement even the memory card is the same, that would probably need DB re-initialization right? Why does DB even need to reinitialize when DB values are supposed to be stored in memory card, it should be retained whatever happen to the CPU right (unless you change the DB itself)? Is there still concept of Cold/Warm restart here in TIA?

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5/7/2020 2:04 PM	Rate (0)
Towome Platinum Expert Joined: 7/9/2015 Last visit: 11/18/2024 Posts: 4028 Rating: (603)	Hi, please check the Table in the following Link - there you will find detailled Information about Init of DB values. Downloading blocks in the "RUN" operating mode to the device (S7-1200, S7-1500) If you want to save them automatically, you can use instruction Writ_DBL: Entry ID: 51434747 Using the "WRIT_DBL" system function you can overwrite the start values during runtime. In this way you get a data backup after a STOP-RUN transition of the CPU without having to declare the variables as retentive. This permits you to back up data created during runtime and reduce the volume of retentive data of the S7-1500 CPU. Set the "DSTBLK" (destination) and "SRCBLK" (source) parameters of the "WRIT_DBL" instruction with the same data block (regardless of whether or not this is in the load memory). You can use the "Snapshot of monitored values" function to apply the current monitored values from the CPU. The current values that are still available after a STOP-RUN transition of the CPU are applied as start values. Regards, Towome
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