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Retain memory

Created by: Noahs at: 12/24/2012 9:34 PM (11 Replies)

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12/24/2012 9:34 PM	Rate (0)
Noahs Posts: 1 Rating: (0)	For how long are the values kept in retain memory DBs? Is it posible that they are deleted after few weeks without power on PLC (I think I experienced such but I'm not sure)? Thanks
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12/25/2012 10:28 AM	Rate (1)
Ganes10 Platinum Member Joined: 8/31/2010 Last visit: 11/6/2024 Posts: 1523 Rating: (229)	Noahs For how long are the values kept in retain memory DBs? Is it posible that they are deleted after few weeks without power on PLC (I think I experienced such but I'm not sure)? Thanks Hello Noahs, The retentive memory is a Flash, so there is no specific period / duration after which the memory will erase. It will stay permenantly, no backup is required.
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1/2/2013 10:05 AM	Rate (0)
jaffar Posts: 6 Rating: (0)	My Dear Friend , I am also facing this problem in my PLC S1214C. can you give clear idea on this. pls ...
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1/2/2013 10:32 AM	Rate (0)
Ganes10 Platinum Member Joined: 8/31/2010 Last visit: 11/6/2024 Posts: 1523 Rating: (229)	Hello jaffar, The data stored in the Retentive memory of S7-1200 does not get erased at any time. Data will stay permanently if a memory space is declared as Retentive.
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7/13/2013 4:17 AM	Rate (0)
r2407 Posts: 111 Rating: (0)	Hi, Do you mean I have to save it in DBs or Retentive memory of CPU can keep data? I'm working with CPU313C Regards
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7/13/2013 6:31 AM	Rate (0)
hdhosseini Diamond Member Joined: 1/28/2009 Last visit: 10/26/2024 Posts: 6852 Rating: (1365)	r2407 Hi, Do you mean I have to save it in DBs or Retentive memory of CPU can keep data? I'm working with CPU313C Regards For each CPU in range of S7 300 you should check their Spec(attatchment): https://support.automation.siemens.com/WW/llisapi.dll?func=cslib.csinfo&lang=en&objid=6ES73135BF030AB0&caller=view In the case of mentioned hardware, It is possible for both memories and DBs. In STEP 7 select the numbers of flags in HW Config-->CPU Properties-->retentive memories-->flags but the DBs are selected while creating DB with option "non retain". In TIA,Also possible for memories in device configuration-->CPU Properties-->retentive memories and again properties of DB. Attachment retain.jpg (1356 Downloads)
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7/13/2013 9:10 AM	Rate (0)
Ayman Elotaify Platinum Member Joined: 5/28/2008 Last visit: 11/6/2024 Posts: 4516 Rating: (839)	Noahs For how long are the values kept in retain memory DBs? Is it posible that they are deleted after few weeks without power on PLC (I think I experienced such but I'm not sure)? Thanks I do not know from where Grop get this piece of info /tf/WW/en/Posts/66190 Gorp Retentive data is stored in non volatile memory and will keep its value "indefinitely"(read: > 10 years). Only the clock is powered by a super capacitor and has a limited retention time. It is mentioned here thatRetention duration is 20 days / 12 days min. at 40 deg. See Appendix 2 ofSIMATIC S7-1200 Easy Book If I remember well, retentive memory duration was 50-190 hours in S7-200. Remanent data areas of the S7-22x Hope this helps.
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7/13/2013 9:18 AM	Rate (1)
Saggy Silver Member Joined: 11/8/2011 Last visit: 11/5/2024 Posts: 387 Rating: (43)	Noahs For how long are the values kept in retain memory DBs? Is it posible that they are deleted after few weeks without power on PLC (I think I experienced such but I'm not sure)? Thanks The retentive memory is a Nonvolaltile, there is no specific days after which the memory will erase. Have look on this threads retentive memory and db problem and How can you back up the actual values of DBs and markers?

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7/14/2013 2:27 PM	Rate (0)
r2407 Posts: 111 Rating: (0)	Hi Hdhosseini, Many thanks for your response. I got your point and I had already checked the retentive flags in hw config, but my only concern is that is there any difference between Retentive Memory(Flag) and DBs? I just need to have 10 bytes retentive in PLC for 2 weeks or so. Now I have used MW0 to MW16, wanna to make sure. Regards
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7/14/2013 2:43 PM	Rate (0)
hdhosseini Diamond Member Joined: 1/28/2009 Last visit: 10/26/2024 Posts: 6852 Rating: (1365)	r2407 Hi Hdhosseini, Many thanks for your response. I got your point and I had already checked the retentive flags in hw config, but my only concern is that is there any difference between Retentive Memory(Flag) and DBs? I just need to have 10 bytes retentive in PLC for 2 weeks or so. Now I have used MW0 to MW16, wanna to make sure. Regards Hello again, Memories and DBs are resources in the CPU with different structure and capabillities.You can refer to "Programming With STEP 7" manual for more help.OK,you have selected the the memories in the H.W Config to be retentive.That is the procedure and about the time data "Kept" intact even machine power off, read post published by my friend "Ayman Elotaify". Best regards Hamid Hosseini
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