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Problem on cpu 315-2DP

Created by: naoufel at: 4/15/2013 6:38 PM (8 Replies)

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4/15/2013 6:38 PM	Rate (0)
naoufel Posts: 11 Rating: (0)	I have a problem on a S7-300 plc cpu 315-2DP. It works for a little time then it pass to stop state and the SF led is light. I connect to the cpu and i read the error in : PLC => Diagnostic/Setting => Module information => diagnostic buffer. i find this 2 errors : 1- decentralized periphery : decentralized station. 2- drive failure (OB unloaded or impossible or FRB missed). What's the meaning of this messages? and how i can fix it?
naoufel Posts: 11 Rating: (0)
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4/15/2013 7:11 PM	Rate (2)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 3/20/2025 Posts: 12344 Rating: (2707)	naoufel i find this 2 errors : 1- decentralized periphery : decentralized station. 2- drive failure (OB unloaded or impossible or FRB missed). What's the meaning of this messages? and how i can fix it? Hello naoufel; There is a bit of information missing in the messgaes you posted. For example, what is the number of the OB declared "missing"? I would guess the CPU is asking for OB86 (based on the message concerning decentral periphery) which is called when you have a problem with a Profibus node. This "OB unloaded or missing" message is displayed when a specific diagnostic OB is required by the operating system of the CPU, but has not been downloaded to the CPU by the programmer. Diagnostic OBs (OBs in the range of 8x, or 12x, such as OB86 or OB122) are bits of code used by the CPU when it detects an event that it considers problematic, like the loss of a Profibus slave, or a programming error. Calling the diagnostic OB allows te CPU to collect diagnostic information on the error and display it in the dagnostic buffer, amongst other things. You will find more information on the subject in the following FAQs: Which organization blocks do you need for error handling? Using the diagnostics buffer of the SIMATIC S7-CPU I suggest you start by creating the OB that is declared missing by the diagnostic buffer (go to the Blocks folder, right-click, New, OB, give it the correct number (as Name), save) and download it to the PLC. At this time, do not program anything inside the diagnostic OB; the parameters of the OB are sufficient for the diagnostic buffer to recieve information on the fault. Open the diagnostic bufferagain when the error happens ( the SF or BF LED should light up, even if the CPU does not enter STOP mode), and you will find a lot more information on the cause of the error. Hope this helps, Daniel Chartier
	Last edited by: dchartier at: 4/15/2013 7:28 PM
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4/16/2013 10:50 AM	Rate (0)
naoufel Posts: 11 Rating: (0)	The OB declared missing is OB86. It can be a problem in the profibus node? But there no errors in the nodes. How i can fix it?
naoufel Posts: 11 Rating: (0)
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4/16/2013 11:18 AM	Rate (0)
playerslight Posts: 1064 Rating: (72)	did you download a blank ob 86 and reread your diagnostic buffer for more infomation as Dchartier sugested ? this willl give you more information as to the faultanother thing to try is check you connections on you profibus for loose or bad shielding
playerslight Posts: 1064 Rating: (72)
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4/16/2013 11:20 AM	Rate (0)
Marcjan Platinum Member Joined: 4/22/2010 Last visit: 2/26/2025 Posts: 5697 Rating: (716)	Hello, OB 86 is called when a profibus error occurs, that can be for a verry short moment. If OB 86 is not present in the CPU it will go to stop. So create and download OB 86 (it may be empty) that will give you time to trace the real problem. Which organization blocks do you have to load into the CPU to ensure that the CPU does not go into the "STOP" status when a remote I/O fails? In OB 86 you can do the error detection to find what module is causing the error. Regards, Marcjan
	Last edited by: Marcjan at: 4/16/2013 11:22 AM I should try to type faster :-) Problem solved? Please let us know! Please no technical questions by PM, use the forum sections for your questions.
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This contribution was helpful to 1 thankful Users playerslight

4/22/2013 1:01 PM	Rate (0)
naoufel Posts: 11 Rating: (0)	Thank u for your help. i find a porfibus module defective that cause the problem of communication. i replace it and it's ok.
naoufel Posts: 11 Rating: (0)
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This contribution was helpful to 2 thankful Users playerslight Marcjan

4/22/2013 1:04 PM	Rate (0)
playerslight Posts: 1064 Rating: (72)	It's still an option to downklload a blnk ob86 this will stop the plc from going into stop mode if it happens again then you can use the diagnostic buffer to trouble shoot
playerslight Posts: 1064 Rating: (72)
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4/22/2013 3:27 PM	Rate (0)
naoufel Posts: 11 Rating: (0)	But if i download an empty OB86 it can make a problem. the problem can happen again but i can't detect it because the cpu is always run (it can make problem to the machine).
naoufel Posts: 11 Rating: (0)
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4/22/2013 3:57 PM	Rate (2)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 3/20/2025 Posts: 12344 Rating: (2707)	Hello naoufel; An empty OB86 will keep the CPU in run, if the problem detected is limited to a Profibus/Profinet slave node problem. Another type of error will require another diagnostic OB in the CPU, and the PLC will still go to Stop mode if there is a programming error detected, for example(this is supported by OB 121, not OB86). But if you have OB86 in the CPU load memory and a profibus node loses its connection, the SF/BF LEDs will be activated, and you will then know there is a problem on the network. Much more information on the source and cause of the problemwill be generated to the diagnostic buffer. It is not mandatory to setup empty diagnostic OBs in your project, if you are not at ease with the idea. But it is standard practice, and the benefits are much, much greater than the possible side effects, in my experience. Try it andtest it for a while, if it does not work for you then take it out of the program (remove the OB86 from the Blocks folder and download the program once again). Hope this helps, Daniel Chartier
	Last edited by: dchartier at: 4/22/2013 4:02 PM
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