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Store Data from Work Memory

Created by: Siemen-Stains at: 12/1/2006 12:53 AM (8 Replies)

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12/1/2006 12:53 AM	Rate (0)
Siemen-Stains Posts: 101 Rating: (0)	Hi! Our SCADA modifies values in Datablocks. Unfortuanatly if a cold boot is done on the S7400 the old values from load memory over write the last values. Whats the best way to synchronize the data? Can i periodicly write data values from work memory back to load memory? if so how? Thanks in Advance
Siemen-Stains Posts: 101 Rating: (0)
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12/2/2006 9:02 AM	Rate (0)
lanong Posts: 5 Rating: (0)	I'm interested also in this problem. I think we can't store data into EEPROM too many times (very often) because of its longivity? But what I need is just to store my proccess data, especially only in case of power loss. It's possible and how? I'm using CPU 313C-2DP with MMC! The second problem I've met is that: my Blocks need more Work memory than that in CPU (40KB > 32KB), so I can't download the project! [:cry:] What should I have to do? I don't know how to calculate needed work memory! [:blush:] Help me please!
lanong Posts: 5 Rating: (0)
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12/4/2006 6:33 AM	Rate (0)
Aret Posts: 2348 Rating: (265)	lanong, S7-300 series works a bit different from S7-400. Your data would be stored on MMC in case of power loss. Do you need more work memory or load memory? First one is for programm execution - it can't be increased. The only thing you can do (without changing CPU) is to make some blocks "unlinked", then they would be stored in load memory and with SFCs you can download them in work memory. If you need to increase load memory then i guess you can take MMC with greater size.
Aret Posts: 2348 Rating: (265)
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12/4/2006 10:47 AM	Rate (0)
lanong Posts: 5 Rating: (0)	Thanks very much. You would help me. I'll try it. I just need more work memory and would like to store proccess data to MMC.
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12/8/2006 11:15 PM	Rate (0)
Siemen-Stains Posts: 101 Rating: (0)	Hey i thought this was my question[:)] I did read about this unlinked memory. Im not sure how you make it but it seems like this; 1)Create a datablock in load memory using SFC 82 2)Copy the data from the datablock in work memory tothe unlinked block in load memory using SFC 84 3)On cold boot, write the data from the unlinked db in load memory back to work memory using SFC 83 Any thoughts on this?
Siemen-Stains Posts: 101 Rating: (0)
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12/11/2006 6:39 AM	Rate (0)
Aret Posts: 2348 Rating: (265)	You can make unlinked blocks in your project - not with SFC. If so - activate "unlinked" checkbox on "General - Part2" tab on creating. For working with such blocks you really need SFC83/84 :^)
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12/13/2006 1:47 AM	Rate (0)
Siemen-Stains Posts: 101 Rating: (0)	Yes, I see. It seems though I cant use those SFC's in the processor I am using S7-400. Im looking at another alternative, maybe the SCADA can back up the values instead.
Siemen-Stains Posts: 101 Rating: (0)
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12/13/2006 12:42 PM	Rate (0)
Ates Posts: 198 Rating: (19)	cant you use ram instead of eprom ? so if you use battery there will be no such problem...
Ates Posts: 198 Rating: (19)
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12/18/2006 10:10 PM	Rate (0)
Siemen-Stains Posts: 101 Rating: (0)	Yes, it is ram. The problem is when someone performs a cold boot. It loads the last values from load meory to work memory, thus over writing the last values. I was hoping to syncronize the 2 memories.
Siemen-Stains Posts: 101 Rating: (0)
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