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Y-Link Profibus network fails if device is powered down

Created by: Scorpioni at: 8/16/2011 8:08 AM (5 Replies)

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8/16/2011 8:08 AM	Rate (0)
Scorpioni Posts: 15 Rating: (0)	Greetings, I'm having the following problem: I'm working on a project that uses a redundant CPU and profibus network on which an Y-link module is installed with a non-redundant profibus network. On this non-redundant network several drives and pneumatic valve islands are installed. The system works fine as long as all the devices configured are powered on, but as soon as one powers down (for example by deactivating the circuit breaker), the 2 IM153 cards of the Y-link start switching over from active LED to BF LED. For example card A is active while card B flashes BF for several seconds after which the LEDs are reversed. The actual Y-link card shows no error and shows the correct DP1 and DP2 LEDs burning). I cannot find a solution when looking through the different LED diagnostics in the Ylink manual. In any case, when this happens, the other devices cannot be controlled by the PLC. Any inputs can still be read but outputs seem to 'fail to arrive' at the equipment. Even stranger, if I remove the powered down equipment out of the HW config and perform a HW download, everything works fine again even though the actual device is still physically connected in the profibus line, making me believe any device or cabling fault is unlikely. Is this some Y-link limitation or is there something I'm missing? Thx in advance, Scorpioni
Scorpioni Posts: 15 Rating: (0)
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8/16/2011 11:27 AM	Rate (0)
Rated X Posts: 1547 Rating: (129)	Hi Scorpioni, which PROFIBUS Device do you power off? Maybe the first or the last one? This is not allowed by the Bus termination. In this case the whole PB will go down. If you can not guarantee that the power of the first or last device is always on you have to install an active bus termination. Refer to: Bus terminating elements for PROFIBUS subnetworks regards Rated X
Rated X Posts: 1547 Rating: (129)
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8/16/2011 11:49 AM	Rate (0)
Scorpioni Posts: 15 Rating: (0)	Thanks for the quick reply. We found out about this problem when there was a faillure with a drive but this drive is situated somewhere in the middle of the line, so I think it has nothing to do with bus termination. We thought maybe it was something specific with that particular drive but others have it as well. A few minutes ago I did a new HW download with the Watchdog of the Y-link turned off and now it seems to work. We'll see next morning if it held up during the night. Anyone know of something the watchdog can interfere with?
Scorpioni Posts: 15 Rating: (0)
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8/18/2011 1:14 PM	Rate (0)
Scorpioni Posts: 15 Rating: (0)	After 2 days of working nonstop without fail, even with several tests (switching off equipment, running of all equipment and powering down several), I can feel confident that it was in fact the watchdog of the Y-link module that was causing problems. Why exactly I have no clue. I hope this can be helpful for someone someday! Regards, Scorpioni
Scorpioni Posts: 15 Rating: (0)
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8/19/2011 6:42 AM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 12/24/2024 Posts: 3029 Rating: (1058)	Scorpioni A few minutes ago I did a new HW download with the Watchdog of the Y-link turned off and now it seems to work. Hello Scorpioni while I'm not to surewhat's really wrong, I'd encourage you to NOT deactivate the Watchdog (aka response monitoring). I can't fomulate it better than the inbuitl Step 7 help on this, which is below: Response monitoring enables the DP slave to react to an error from the DP master or to a break in the data traffic on the bus. If the DP slave is not addressed within the configured Response Monitoring Time, the slave goes into the safe state (all outputs are set to "0" or substitute values are output). Danger: If you switch off the response monitoring, then the outputs of the appropriate DP slave may not be set to "0" in the event of an error. Consequently, it is strongly recommended that the response monitoring is deactivated only during commissioning. I fear that all you do with the "Watchdog deactivated trick" is to mask the underlying problem (i.e. dealing with the symptons instead of eliminating the cause). I suggest you check the following: 1.) Check part number and firmware of your IM153-2's (while I doubt thatit is afirmware issue, it won't hurt to check) 2.) Get hold of a Profibus Anlyser (my choice: Procentec's Profitrace 2) and analyse the segement (with all devices running and with selected ones switched off). Perhaps the drives still have 24V control power control when isolated and start "misbehaving" on the bus (they of course shouldn't, but thequestion iswhat type of drives do you have, do they have a certifed Profibus DP Slave interface etc.) I hope this helps and please let us know what you find.
	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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This contribution was helpful to 1 thankful Users H-H

5/15/2014 6:13 PM	Rate (0)
H-H Platinum Member Joined: 7/2/2008 Last visit: 9/30/2024 Posts: 928 Rating: (309)	Hello Everyone, I know it's an old thread but I have an update that might be useful for similar problems. Few days ago, One of our systems had a similar problem in a 400H system with Y-Link for some ET200S stations, some drives and a soft starter. The soft starter was taken out for maintenance and the Y-Link network was down. All inputs were read but the output image was not transferred to any peripheral. I made a new HW config. without the soft starter and everything worked fine. I contacted Siemens technical support, I was advised to update theET200M firmwarebecauseSiemens has solved some starting up issues for the Y-Link(Please, check the firmware update descriptions). However in my case, it was discovered that a small check mark is responsible to "start up Y-Link when expected/actual configuration match". The check mark might be deceiving if someone is used to the check mark in CPU properties "Startup if preset configuration does not match actual configuration". I moved the check mark and downloaded. Everything works fine. This doesn't mean that the firmware update is not important. I still advise everyone to update his ET200M firmware to the latest. Best regards, H-H Attachment Y-Link Problem.pdf (350 Downloads)

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This contribution was helpful to 2 thankful Users fritz hdhosseini

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