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S7-300F communication issue to MP277/MP377

Created by: railway signaling at: 1/3/2012 10:34 PM (6 Replies)

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1/3/2012 10:34 PM	Rate (0)
railway signaling Posts: 3 Rating: (0)	Hello, I didn't see any subject in the forum addressing this issue so here is my question. I have several S7-300's networked via profibus. Four of the S7's have HMI (MP277's) tied to them also connected via profibus. On two occasions now the HMI panels have reasonably simultaneously quit talking to their respective S7. Has any one seen this before or have any idea what may be causing it? The installation has been in place about 3 years and the other incident was nearly a year ago. The HMI panels are also tied together on a separate network. After looking at the first incident (no information in diagnostic buffer, no information from scalence switch log, and nothing abnormal in the HMI log) and finding nothing I hoped it was a one time anomoly, now that it has happened again I really need to figure out what is happening to find a resolution. The S7's continue to function normally and the HMI panels function fine after powering them off and back on. Any thoughts or ideas are definitely welcome.
railway signaling Posts: 3 Rating: (0)
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1/4/2012 5:40 AM	Rate (0)
Asanga Regular Member Joined: 2/5/2009 Last visit: 2/1/2025 Posts: 11 Rating: (0)	Dear Friend, Once this problem occurs , is the panel seems to be stuck mode or displays '' #### ' on value cages ?. I have faced this type of problem that was mainly due to short circuit of the Profibus intermittantly. Regards, Asanga.

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1/4/2012 8:15 AM	Rate (0)
Darius Platinum Member Joined: 9/28/2005 Last visit: 12/9/2025 Posts: 2957 Rating: (243)	Hi, Indeed, sounds like network problem (physical). Well you need to be sure that you have correct bus termination, correctly connected connectors and try to lower speed of the network if it is higher than 187.5 kbps.
	Best regards, Darius
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1/4/2012 4:34 PM	Rate (0)
railway signaling Posts: 3 Rating: (0)	Ok so here is the thing, I have 14 S7-300's tied together and 4 of the S7's are hooked up to HMI panels. The panels work flawlessly for a year and suddenly they all lock up (yes values show ###). While they are locked up the S7 continues to operate just fine no error or event records posted in diagnostic buffer. At the same time I have ethernet connection to the HMI panels that continues to function normally, I can ping the panel and also can use smart client to web into the panel. I believe there is something happening on the ethernet Lan that causes the panel to stop communicating via profibus. The IT department (in charge of the LAN and associated equip) denies that anything was abnormal when these lockups occur. Also I have another location with 4 S7's not tied (via profibus) to the 14 listed above. They are connected to 2 MP377 panels and networked on the same ethernet LAN. These panels also locked up when the others above locked up. The profibus network is running 1.5Mbs, but as the problem occurs at all locations when this happens I don't think that could be the issue. Also if I had a bad connection it shouldn't affect all locations either. Any additional ideas given this further information would be greatly appreciated.
railway signaling Posts: 3 Rating: (0)
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1/5/2012 4:50 PM	Rate (0)
Tweety Posts: 3037 Rating: (192)	Hello, Youshould test the Profibus connection of all panels step by step. You have download the option of Sm@rt service to the panels. You should check the setting of the connection ofPLC in yourWinCC flexible projectand your Step7 project. How do you configure a connection between WinCC flexible Runtime (PC/Panel) and a SIMATIC S7-300/S7400 via PROFIBUS/MPI? Tweety
Tweety Posts: 3037 Rating: (192)
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1/5/2012 5:06 PM	Rate (0)
railway signaling Posts: 3 Rating: (0)	The connections are good all six panels will freeze up at the same time. The panels are separted by roughly 15-20 miles and are not all on the same profibus network. The only thing they have in common is an ethernet LAN to remotely web into the panels via smart client. The connection between S7 and the HMI is indeed profibus but I don't see how this can be anyway related. If one panel occasionally froze up then probably but the six panels will work flawlessly for some months (as long as a year) and then all of a sudden they all stop working at the exact same time. I believe that something is happening on the Ethernet LAN that the panels do not like and it then terminates the profibus connection. Again there are no error or event messages in the diagnostic buffer.
railway signaling Posts: 3 Rating: (0)
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1/9/2012 2:20 PM	Rate (0)
Tweety Posts: 3037 Rating: (192)	Hello, Which Version of WinCC flexible do you use? Do you use scripts, logs and many arrays in your MP277 and MP377 project? Haveyou adhered to the system limits for her projects? You can see the system limits in the help of WinCC flexible. Tweety
Tweety Posts: 3037 Rating: (192)
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