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I/O access error

Created by: dande74 at: 12/19/2008 9:11 AM (11 Replies)

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12/19/2008 9:11 AM	Rate (0)
dande74 Bronze Member Joined: 2/5/2007 Last visit: 9/9/2023 Posts: 101 Rating: (11)	Hi! I've developed a FB to handle pressure sensors which has profibus interface. When I developed the FB I connected three sensors to a 315-2 DP. Everything is working on my test system. But when I implemented the FB to my customers system I sometimes, say 1 of 5, get I/O access error when triggering the FB. I'm attaching the diagnose buffer. I don't think it says more than I just explained. Can it be something with the bus? Bus parameters, timeout? I know they have some OBT's and four operator panels. Attachment IO access error.pdf (386 Downloads)

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12/19/2008 9:32 AM	Rate (0)
umencho Diamond Expert Joined: 3/21/2006 Last visit: 1/14/2025 Posts: 10239 Rating: (1182)	Hello I think this problem with Bus connection. Address of the affected DP slave: station number: 23. You can check profibus connections, also distance from Master. The other possibility is to loose power suply of this DP slave... regards
	Last edited by: UMENCHO at: 12/19/2008 9:34 AM
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12/19/2008 9:49 AM	Rate (0)
Aret Posts: 2348 Rating: (265)	4 panels on the same network? Then you are lucky,thatproblemsappearonlysometimes. Think your CPU load from communications is not enough for such system (but that really depends on how much tags you use on OP). Can you temporaly switch off some of OPs(bestifyouleave1) andfindoutiftheseerrors wouldfade away.
Aret Posts: 2348 Rating: (265)	Last edited by: Aret at: 12/19/2008 9:49 AM
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12/19/2008 10:01 AM	Rate (0)
dande74 Bronze Member Joined: 2/5/2007 Last visit: 9/9/2023 Posts: 101 Rating: (11)	UMENCHO Hello I think this problem with Bus connection. Address of the affected DP slave: station number: 23. You can check profibus connections, also distance from Master. The other possibility is to loose power suply of this DP slave... regards I forgot to mention that I get the error on all three sensors sporadically. I know that the connection isn't done by the schoolbook. Maybe we got something here.

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12/19/2008 10:22 AM	Rate (0)
dande74 Bronze Member Joined: 2/5/2007 Last visit: 9/9/2023 Posts: 101 Rating: (11)	Aret 4 panels on the same network? Then you are lucky,thatproblemsappearonlysometimes. Think your CPU load from communications is not enough for such system (but that really depends on how much tags you use on OP). Can you temporaly switch off some of OPs(bestifyouleave1) andfindoutiftheseerrors wouldfade away. Ok. So you say. I thought 4 panels wouldn't be any problem. The same customer has one system with 11 panels without any I/O eccess error I attach a schematic drawing of the network. Attachment Profibus network.pdf (343 Downloads)

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12/19/2008 11:39 AM	Rate (0)
umencho Diamond Expert Joined: 3/21/2006 Last visit: 1/14/2025 Posts: 10239 Rating: (1182)	Hello Did you connect this sensors to the same remote I/O that gives error? What is the distance to this remote I/O? Or try to disconnect one or two of sensors and see what's happend. Maybe Aret is right. CPU is not so powerfull to "keep" the bus system. I also had problem with profibus line on CPU 315-2dp and I can't solved the problem, even using repeater. But changing the CPU with 416-3dp download the same program and everythink goes OK. regards

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12/19/2008 11:55 AM	Rate (0)
dande74 Bronze Member Joined: 2/5/2007 Last visit: 9/9/2023 Posts: 101 Rating: (11)	It is the on the sensor the I/O access error occurs. The distance is not more than 10 meters. But as you can see they are using OBT's. I think it is overkill but they did it this way. I mean, it shouldn't hurt do use fiber, right? I'll try both your and Aret's suggestion. Tanks

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12/23/2008 12:15 AM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 1/17/2025 Posts: 3030 Rating: (1058)	Dear Dande74 if you are really using OBT's your firstproblem is that you are only allowed to connect ONE device to its RS485 port! Please check the Simatic Net Profibus networks manual for more on this (link: http://support.automation.siemens.com/WW/view/en/1971286). If you need to keep the topology as is, youshouldreplace the OBT's with OLM's (note that OBT's use plastic fiber so the OLM version needs tobe a "P"one). Other things to check are correct termination of each RS485 copper segment(Terminator must beON at the Start and End of each RS485 Segment). I hope this helps and make sure to have a merry X-Mas.
	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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12/29/2008 9:06 AM	Rate (0)
dande74 Bronze Member Joined: 2/5/2007 Last visit: 9/9/2023 Posts: 101 Rating: (11)	Thanks for the suggestion. I'll try this aswell. Will come back with a report as soon as I have tested.

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12/29/2008 3:19 PM	Rate (0)
Late Platinum Expert Joined: 1/7/2006 Last visit: 12/23/2024 Posts: 2705 Rating: (320)	Hi Dande, Please notice that the connectors for the OBT and the OLM P-version are not the same !
	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......
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