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| 4/27/2010 11:03 PM | |
Joined: 3/25/2008 Last visit: 1/28/2022 Posts: 232 Rating:
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Hello dear colleagues. I have a CPU S7-317-PN/DP firmware version 2.5. When i try to download an DB larger than 300Kb, the simatic managger tel me that load memory is not enough, and askme if i wish to compress it, i acept but even when i compress the memory i'm not able to download those "bigs" DB's. So i just decide to erase all, i have erased PLC and MMC; and after that i have downloaded the full program to PLC again, and every thing was pretty good. But then i made some changes into someGraph FB's, and when i try to download them the simatic manager told me "Load memory is not enough" and also ask me again if i wish to copress, so i acept again but the blocks could not be downloaded to the PLC (the instace DB's for those FB's). After that i just check onlinememory properties, and i foundthat load memory has 600Kb free space (more or less), Work memory has 298Kb free, but retentive memory is full 100%; i know that if i change some DB's properties from retentive to non retentivethen i canreduce the size ofused retentive memory. So, having said that i wish toknow please: 1.-Retentive memory used 100% is the cuse of my problem?I mean if i reduce the size of retentive memory will i be able to download the "big" DB's. (Remember, they already exist on PLC but i can not download them again). 2.-I have avaiable an S7-319-3PN/DP CPU, if i change my old317 with this new CPU, is posible to solve the problem? Please refer to attached file, there are some screen shots about online memory properties. BTW: i have checked thechnical data for 319 CPU, and he's retentive memory is 700Kb,the retentive memory for 317 is 258Kb. Thanks all you for your help and have a nice day AttachmentMemory.zip (280 Downloads) |
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| 4/28/2010 6:12 AM | |
Joined: 10/7/2005 Last visit: 9/18/2024 Posts: 3021 Rating:
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Hello TEBANCHIguess thisa typing mistake, 64KB is the maximum size for a DB in your 317 (or are you just testing us and mean Kilo BITS since the 'b" is lower case?). To tell you the truth, I never had the problem of "running out of retentive" memory. I do concur though that your full retentive memory is the cause of your download problem. Bear in mind that a download requires enough free space for the whole block to begin with which you simply do NOT have left (the old block is not deleted but only marked as invalid and will be "removed' if compression is done). I suggest you test the following: 1. Put the CPU into Stop 2. Delete the DB online 3. Compress 4. Try to download the DB This procedure shouldwork as it in principle achieves the same as clearing the memory and doing the download (except you are now doing only for one block). Declaring some DB's as "Non Retain"and thusfreeing up retentive DB memory should of course also solve your problem (note that "Non Retain" DB's obvioulsy do NOT retain theiractual valuesthough). It should, since it has a larger retentive memeory area for DB's (as you already know). Last but not least, you may find the following FAQ's useful too: How can the program runtime be optimized if the main memory of the CPU is too small for the runtime-relevant STEP 7 program?" Retentivity behavior of S7-300 CPU 31x and complete devices C7-6xx with MMC I hope this helps |
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| 4/29/2010 11:45 AM | |
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Joined: 10/7/2005 Last visit: 9/18/2024 Posts: 3021 Rating:
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Good question derTEBANCH assuming you stick with the "retentive" default for all DB's (i.e. you do NOT set the "Non Retain" tick mark for any DB's), the "Data" value for"Size the work memory" (Block Folder properties)would also be the required size of the retentivememory area. Let's say though that you did declare some of the DB's as "Non Retain": In this case theBlock Folder properties does not differentiate between retentive DB's and non-retentive DB's and isn't useful anymore to work this out (Siemens Step 7 Developers take note: it wouldn't hurt to have this feature in future versions). You do however have another way to work it out: Selectall DB's in Simatic Managerthat are retentive and have a look in the bottom right corner of the Simatic Manager (it will show you the total size of all selected DB's). I hope this helps |
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