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OB122 Problem?

Created by: henno2000 at: 7/2/2009 11:48 PM (2 Replies)

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7/2/2009 11:48 PM	Rate (0)
henno2000 Posts: 177 Rating: (0)	Hi, I have setup a network of IM-151-8-F PLCs and have incorporated the following OBs - 35, 83, 85, 86, 121, 122. I have successfully configured all of the hardware, but still have a system fault on the CPUs. Looking into the diagnostic, the problem relates to an IO access error for a memory address relating to OB122. Opening OB122, there is nothing called. I have also search the program for the referenced memory address, but it is not found. Has anyone experienced this problem before? Regards, henno2000
henno2000 Posts: 177 Rating: (0)
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7/3/2009 12:19 AM	Rate (0)
IBN-Service Posts: 8946 Rating: (999)	henno2000 Hi, I have setup a network of IM-151-8-F PLCs and have incorporated the following OBs - 35, 83, 85, 86, 121, 122. I have successfully configured all of the hardware, but still have a system fault on the CPUs. Looking into the diagnostic, the problem relates to an IO access error for a memory address relating to OB122. Opening OB122, there is nothing called. I have also search the program for the referenced memory address, but it is not found. Has anyone experienced this problem before? Regards, henno2000 Hi henno, maybe you just go in the wrong direction! If there is an IO access error, then the OB122 will be called! If there is no OB122, the CPU will go to STOP. There is NO fault in the OB122 but the OB122 call is the reaction of such fault! (Just try an empty OB122 to confirm my opinion!) In the diagnostic, there must be a message that told you, which adress is not attainable and also the block in which the adress is used. Also in OB122 you find a local variable which tell you this adress! It is possible, that the adressing is done indirectly, than it is not so easy to find the position in the program, but usually with the diagnostic entry you can locate the block wich causes the error (NOT OB122, have a look at the message before!).
IBN-Service Posts: 8946 Rating: (999)
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7/3/2009 8:59 AM	Rate (1)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 1/17/2025 Posts: 3030 Rating: (1058)	Hello henno2000 just to complement IBN's excellent explanation: S7 300's (which your IM151-8 belongs too) are not all that "powerful"in their CPU diagnostics buffer entries in cases where you "supress" a CPU Stop by having the correspondingerror OB in the CPU. You'll find it is easier topinpoint the problem(e.g. which FC/FB at what command caused it) if you delete the error OB (OB122 in your case) from the CPU (go for online view to do so), let the CPU "Stop" due to the errorand then look into the diagnostic buffer (it will not only tell which non-existent I/O address you tried to access, but also which FC or FB it was and you can directly go to the command in question via the "Open Block" button). I hope this helps P.S: If you are still stuck you can do a saveof the diagnostic buffer and post it together with your S7 project here.
	Last edited by: fritz at: 7/3/2009 3:05 PM Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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