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TIA ladder TON problem/bug

Created by: MPL@PCA at: 8/20/2010 9:00 AM (4 Replies)

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8/20/2010 9:00 AM	Rate (0)
MPL@PCA Posts: 14 Rating: (0)	System: S7-1212C + KPT400 I have this bit of laddercode in my program: (attachment) The problem is when I link M1.4 to an appearance change on the KPT. (a circle which turns dark when = 1) On the panel this circle just blinks irregularly at +- 3 second instead of the given 30 seconds. And this while M1.4 = 1 the whole time (monitored in a watch table). When I set M1.4 = 1 without the TON, this problem is gone. Can anyone explain to me how the TON behaves and how it could cause this? Thanks Attachment s7basicprob.JPG (126 Downloads)
MPL@PCA Posts: 14 Rating: (0)
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8/20/2010 11:26 AM	Rate (0)
Robster Gold Expert Joined: 5/28/2008 Last visit: 3/29/2021 Posts: 1341 Rating: (135)	Hi, I think it isn't a problem with TON. Please have a look that you use M1.4 only at this place in program. Make sure that MB1 isn't used as clock memory. To find this out, take a Bit in a global DB instead of M1.4. regards

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8/20/2010 1:38 PM	Rate (0)
MPL@PCA Posts: 14 Rating: (0)	Ah ***, It's probably a problem that MB1 is defined as system memory byte (attachment). It says that M1.0 -> M1.3 is used. However it will probably write the whole byte instead of each seperate bit. :( This way it would explain the blinking. Because of the cyclic execution of the PLC it will not have been visible in the monitor view, nor would it affect the programming. It's a coincidence I skipped M1.0 -> M1.3 and I didn't use MB0 because I know from Step-7 that is the clock byte. I just didn't count on the fact that Step-7 basic introduces a System memory byte. Thanks alot Attachment sysbyte.jpg (104 Downloads)
MPL@PCA Posts: 14 Rating: (0)	Last edited by: MPL@PCA at: 8/20/2010 1:58 PM Last edited by: MPL@PCA at: 8/20/2010 1:38 PM Thanks alot
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8/23/2010 4:39 PM	Rate (0)
Robster Gold Expert Joined: 5/28/2008 Last visit: 3/29/2021 Posts: 1341 Rating: (135)	Ok, so you fixed your problem?

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8/24/2010 8:03 AM	Rate (0)
MPL@PCA Posts: 14 Rating: (0)	yes, thank you
MPL@PCA Posts: 14 Rating: (0)
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