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Incomplete Backup on S7-300 & 400

Created by: mchristisen at: 11/2/2008 10:40 AM (3 Replies)

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11/2/2008 10:40 AM	Rate (0)
mchristisen Posts: 2 Rating: (0)	Hi all. I seem to be getting incomplete backups on S7-300 and 400. For my purposes a backup is connecting to the plc cpu with an mpi interface and transferring a copy of the program on the plc to a PC for safe keeping. Then the backup would be used in case of some type of hardware failure. My concern is that the program pulled from the plc seems to be missing some vital information. For example our application incorporates several quadrature encoders and the counters and inputs are completely missing from the backup. I am afraid that our backups will not fully restore a system if a hardware failure occurs. Can anyone give me some advice on this matter? Thanks, Matt
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11/2/2008 2:30 PM	Rate (0)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 6/4/2023 Posts: 12033 Rating: (2595)	Hello Matt; You could do an Online/offline block compare of the backup program and the one loaded in the PLC. You would get errors based on the fact that the symbols are not uploaded from the CPU to the PC, but at least you would see if major blocks and data are missing. This should reassure you or at least show you that your fears are justified... Here is how Siemens introduces the subject: http://support.automation.siemens.com/WW/view/en/18652056 Programming with STEP 7 9.3.5 Comparing Blocks Introduction To compare blocks that are in different locations, you can start the block comparison process in either of the following ways: Go to the SIMATIC Manager and select the Options > Compare Blocks menu command. In the "Compare Blocks - Results" dialog box that is displayed, click the "Go to" button. The results of the comparison will appear in the program editor (LAD/FBD/STL) in the "Comparison" tab Go to the program editor. Select the Options > Compare On-/Offline Partners menu command. The following sections explain how the block-comparison process functions. In the following discussion, a distinction is maintained between logic blocks (OBs, FBs, FCs) and data blocks (DBs). Hope this helps, Daniel Chartier
	Last edited by: dchartier at: 11/2/2008 2:32 PM Last edited by: dchartier at: 11/2/2008 2:32 PM
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11/4/2008 8:21 AM	Rate (0)
mchristisen Posts: 2 Rating: (0)	Thanks Daniel. I had seen "compare blocks" before but didnt know how to get it highlighted so I was never able to use it. Flipping thru the manual and I found that blocks needed to be selected for the compare blocks function to be available. I did have to put the plc in stop mode for the blocks to compare without error. Kept getting checksum errors with the plc running. Anyway, thanks Daniel. So, if the blocks compare without error, can I feel comfortable that the entire program in the PLC including hardware and connections configurations will be adequately backed up?
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11/4/2008 12:55 PM	Rate (0)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 6/4/2023 Posts: 12033 Rating: (2595)	Hello Matt; If all the blocks pass the compare test, fhen you can feel sure that the logic you programmed will be OK when you load it from the backup file. Of course, if you had accress to a test rig, you could download the upgrade to this PLC and test it; thios would be the most reassuring procedure. Now, earlier you mentionned "vital data" missing from the backup.What are you refering to, in your case? If you have doubts about specific areas of your applicatioon, then we would have to address them directly, point by point. Hope this helps, Daniel Chartier

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