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I'm suffering of OB86 : Rack Failure

Created by: trialghost at: 9/28/2007 7:16 AM (10 Replies)

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9/28/2007 7:16 AM	Rate (0)
trialghost Regular Member Joined: 9/28/2007 Last visit: 4/19/2023 Posts: 18 Rating: (1)	Hi, I’m looking for a specialist Advices General Information: I use a CPU 414-3 DP - 6ES7 414-3XJ00-0AB0 / V3.1With a 40 DP Slaves (ET200, POSMO, ETR-temperaturrregler, ….....) Problem Identification: I receive from my SCADA Sys. The Following Alarms in same time System: S7 - OB122 Access Error System: S7 - OB86 Rack Failure System: S7 - OB85 Program Execution Error and i think that the OB86 isthe cause for the others ( OB 85 , 122 ) and when i Check the Diagnostic Buffer The addresses of the failed distributed I/O station differ from time to another.(This problem appeared over 15 times) so I tried the common things like: 1- Adding a Diagnostic Repeater in H/W Config. To amplify the signal And the problem comes again 2- Changing the CPU by Spare one. And the problem comes again And I’ve been advised that a PROFI-BUS analyzing and measuring should be made by a profibus specialist.So if any one any one could help me on this . I'll be very very grateful. * thank you for reading my message

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9/29/2007 10:37 PM	Rate (0)
J_Bell Posts: 5822 Rating: (411)	Hello, well... as far as I see it the issue is not that the OB 86 or 122 is called... the issue is that Slave drop from the Bus and come back, isn't it? So you, or better the specialist you should call on site, has to figue out what is going on. Have you checked the Busparameters on the Bus? Have you checked the wiring and grounding? Are the cables layed that way that there is no interfearance to care about? These are just some questions... the installation of a Repeater is not always the solution... but important, especially if you have 40 Slaves and at least one Master. Best regards J_Bell
J_Bell Posts: 5822 Rating: (411)
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9/30/2007 6:53 AM	Rate (1)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 9/25/2023 Posts: 12153 Rating: (2624)	Hello trialghost; Sounds like you have a bus topology problem. In my experience, here is what I would recommend you check: -are you using spur lines on this network (star topology, a dropline between the main bus and the DP node)? If so, make sure that the spurs are as short as possible; we use them at max. 20 cm, at 1,5 MB. Longer than that, they tend to allow reflexions on the line, causing access problems like you show. -with 40 nodes, you need at least one repeater (above 31 nodes); you say you have setup a diagnostic repaeater, so that should be taken care of, especially if you installed it after the first third of the bus.. But even then you might have problems, as each segment's length depends on bus speed (100 m at 12 mB, 400 m at 500 kB...). The easy way to determine if this is a problem is to lower bus speed on the master, and check if the bus stabilizes. If it does, check the details of the bus installation. -there could be a termination problem. Adequate termination eliminates reflexions on the bus; adequate termination requires that the end-points of the bus be at all times powered. If there is any possibility that you lose power on the endpoints of the bus (for commissioning or maintenance purposes), try using independantly powered bus terninators (Siemens sells them)-- and keep those powered permanently. -of course, cable and connections should be inspected anytime you have a problem of this type. If certain nodes come back regularly on the PLC diagnostics, make sure to check whether connectors are adequately installed; actually, take the time to verify all nodes, withonly 40 it is a short exercise.Make sure especially that the cable shield is properly clamped in the connector; vibration can induce random disconnection of the shield in loose connectors, which can cause havoc on a network. That should give you enough to ponder at this time. If you still have problems with your network after checking these issues, you might have to sue a scope to look at the waveforms running on the bus, and giagnose your problems.Come back to the forum for more help. Hope this helps, Daniel Chartier

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10/2/2007 9:38 PM	Rate (0)
trialghost Regular Member Joined: 9/28/2007 Last visit: 4/19/2023 Posts: 18 Rating: (1)	Hi *Daniel Chartier* , J_Bell first i would Like to thank both of you for your Fast replay. it seems that i found expertsin the forum more than i thought, there are many details in your messages and i'm not like you "i mean your experience" any way, ican tell you that : about connectors checking the sockets had been done and the problem still about Shield i found some cables with littel loose shieldi fix them but the proble still about parameteractually i don't know how to check. but the production line workking good for 2.5_years so i dont't think the Bus parameter changed and finally about interfearance the path of all cables is designed by specialists and again its running for 2.5 years without problems but here a new information i notice it. "please look at the attached HW config " in the drives bus we had a defined problem " failure of 9 drives in end of the network" and we fix this problem with adding a repeater "directly before the 9 drives" and the problem did not came again. but our pre-discussed problemshow for first time after 10 days fromthe drives failure prob. is any link between the two problems in your mind we decide to uninstall the repeaters we added. and wait. thank you again Attachment HW config.GIF (478 Downloads)

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10/4/2007 9:28 AM	Rate (1)
Ates Posts: 198 Rating: (17)	in this case, i would double check or triple check my connectors (espeacially shieldings) and if the line is more then 80m i never use 1.5mb as dp speed, I always use 187.5. (I know it written 200m in catalogs but mine is experinced with pain). I think repeater is solved solved your problems coz it ampilfies the signal, so if there is a weaknes in line then it will surplus your weakness, its a good solution. but some times (espeacially 1 time) it didnt helpd me and in the end i helplesslydeleted line i disconnected all connectors my self not electricians and then rebuilt it.. it worked for me
Ates Posts: 198 Rating: (17)
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12/22/2007 1:05 PM	Rate (0)
trialghost Regular Member Joined: 9/28/2007 Last visit: 4/19/2023 Posts: 18 Rating: (1)	Dear Ates: i'm sorry for my slow reply, butihadtowaittheresult i just wanna to thank you about your advices specially when you said: i would double check or triple check my connectors (espeacially shieldings)........ i disconnected all connectors my self not electricians and then rebuilt it.. it worked for me beacuse i recheck the socket connections specially shield and it was almost one month ago, the problem till this date never come , and i think it will not i will contact you ifanythigshowup thank you again

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12/22/2007 6:06 PM

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Late

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Joined: 1/7/2006

Last visit: 7/3/2023

Posts: 2705

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Hi Ghost,

If you want to know more to build up a Profibus network then the next handbook will help: SIMATIC NET PROFIBUS Networks

Aret mentioned that he never goes to a higher Baurate then 187,5 kBit/s.....

on this length of network. With 187,5 kBit/s you may go to 1 km.... So the next step 500 kBit/s is (for sure) useable for 400 meter.

If you built up the network as mentioned in the handbook and use the right cablework and the right connectors, like the Profibus Fast Connect connectors, then you may go even to 12 MBit/s with the length you have ......

The connectors that are perfect are:

6ES7972-0BB50-0XA0	Profibusstekker FastConnect 90 graden incl. PG aansluiting
6ES7972-0BA50-0XA0	Profibusstekker FastConnect 90 graden
6ES7972-0BB60-0XA0	Profibusstekker FastConnect 35 graden incl. PG aansluiting
6ES7972-0BA60-0XA0	Profibusstekker FastConnect 35 graden incl. PG aansluiting
6GK1500-0FC00	Profibusstekker FastConnect 180 graden axiaal voor displays
The cable 6XV1830-0EH10	Profibuskabel FC Standard
Tool 6GK1905-6AA00	Fastconnecting stripping tool

I hope that the answer will help, if you have still questions, don't hesitate to ask me.

All the best, Late
Never say never, think in solutions, not in trouble......

1/4/2008 9:30 AM	Rate (0)
Thijs Posts: 121 Rating: (16)	I've found by experiance that a propper earth connection is also helping te create a reliable network. I've sometimes connected the profibus cable shield directly to the earth. With longer lengths you should consider the earth connection between the different connections points.
Thijs Posts: 121 Rating: (16)
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2/19/2008 12:12 AM	Rate (0)
trialghost Regular Member Joined: 9/28/2007 Last visit: 4/19/2023 Posts: 18 Rating: (1)	=== Edited by trialghost @ 19.02.2008 00:45 [GMT ] ===
	Last edited by: trialghost at: 19.02.2008 00:39 Last edited by: trialghost at: 19.02.2008 00:39 Last edited by: trialghost at: 19.02.2008 00:31 Last edited by: trialghost at: 19.02.2008 00:16
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2/19/2008 12:35 AM	Rate (0)
trialghost Regular Member Joined: 9/28/2007 Last visit: 4/19/2023 Posts: 18 Rating: (1)	hi every one the problem of Rack Failure is come back after almost 3 months , i thought it went specially after shielding reCHECK , but it come again now if i reduce the baudrate from 500 kb/s to 187.5 kb/s could this solve the problem , and what is risk of reducing it. sorry if i disturbing you Attachment only 1 of 4.GIF (470 Downloads)

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Created by: trialghost at: 9/28/2007 7:16 AM (10 Replies)

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