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Old March 16th, 2017, 11:08 AM   #1
bhedding024
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Siemens Box PC 627b / WinCC Communications Issue or?

I have a machine running with a Siemens 627b box pc connected to IO modules via ET200M interfaces and running a WinCC application. There is also a SIMATIC Flat Panel connected via DPI and USB via a Remote Panel Kit which basically converts the USB to a cat5 cable between the flat touch panel and the PC. My issue is that sporadically the screen variables lock up and the touch screen becomes inactive. The USB keyboard and mouse connected to the Flat Panel also stop working. If I move the keyboard and mouse to the local USB ports on the box PC they still do not work. At first I was thinking the OPC server was locking up and that is why the data on the screen was freezing up, however the loss of the USB functionality has got me thinking otherwise. Any ideas? Any other info that would help troubleshoot? Thanks!
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Old March 16th, 2017, 11:28 PM   #2
mk42
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I think the 627B's are fairly old in terms of a PC, they were released 10 years ago, discontinued 6 years ago and you can't even get (official) spare parts any more. It could simply be a PC failure (bad motherboard, something like that). Even IPCs wear out eventually.

On the software end, one program locking up could hypothetically cause the USB ports to lag or stop updating. Can you chart the CPU usage over time, to see if it spikes when you notice the problems?
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Old March 17th, 2017, 10:45 AM   #3
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I'll take a wild guess.
There is probably a WinAC RTX on the box PC. The WinCC application dont communicate directly with ET200M (not impossible, but unlikely).
Maybe the PC is blocked by dust, or a fan has stopped working. If the CPU overheats it will throttle down, maybe the RTX will continue to operate (because it is prioritized over regular programs), but everything else dont get enough CPU power to respond, thus Windows seems to become unresponsive.
These box PCs some times have some monitoring functions, to check for temperatures and fan speeds. You could try to investigate that.
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Old March 20th, 2017, 08:54 AM   #4
bhedding024
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Thank you for the suggestions. I actually looked at the CPU usage and it is pegged out nearly all the time by an application called "s7wlpapx.exe" which from what I understand is just basically a tool to keep the PC from going into hibernation. Seems awfully odd to me, but a lot of what I've experienced with Siemens thus far has certainly been an experience after being almost exclusively involved with AB hardware for the past 15 years or so. I was lucky enough to observe the locking up first hand this morning and the first thing that stopped responding was the touchscreen, then the mouse stopped working maybe 30 seconds later, followed by the keyboard shortly after that. Then the system clock on the WinCC app froze. The PLC cabinet is fitted with some nice filters all of which have been removed for some very logical reason I'm sure <eyeroll>. The outside of the PC around the fans is pretty dirty so that could certainly be the culprit. As a side note, when this machine retrofit was done in 2012 by the OEM in Germany I looked into getting a spare 627B and realized that it was already obsolete! Of course the attempts to replace it with a more current version have been met with the typical responses from these apparently far more knowledgeable about such things, you know like accountants and such...anyways I digress. Thank you for your help!
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Old March 20th, 2017, 09:30 AM   #5
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Quote:
Originally Posted by bhedding024 View Post
Thank you for the suggestions. I actually looked at the CPU usage and it is pegged out nearly all the time by an application called "s7wlpapx.exe" which from what I understand is just basically a tool to keep the PC from going into hibernation. Seems awfully odd to me, but a lot of what I've experienced with Siemens thus far has certainly been an experience after being almost exclusively involved with AB hardware for the past 15 years or so. I was lucky enough to observe the locking up first hand this morning and the first thing that stopped responding was the touchscreen, then the mouse stopped working maybe 30 seconds later, followed by the keyboard shortly after that. Then the system clock on the WinCC app froze. The PLC cabinet is fitted with some nice filters all of which have been removed for some very logical reason I'm sure <eyeroll>. The outside of the PC around the fans is pretty dirty so that could certainly be the culprit. As a side note, when this machine retrofit was done in 2012 by the OEM in Germany I looked into getting a spare 627B and realized that it was already obsolete! Of course the attempts to replace it with a more current version have been met with the typical responses from these apparently far more knowledgeable about such things, you know like accountants and such...anyways I digress. Thank you for your help!
Oh yeah, If WinAC RTX is installed, then the CPU usage won't be very useful. My bad. Because the realtime part of the kernel operates outside/below Windows, it doesn't know how much processor is getting used on the realtime side. This means it could either go to sleep or decrease the processing speed to save power. This causes delays/faults/shutdowns on the PLC side, which is obviously undesireable, so the service you mentioned was hacked together to trick Windows into thinking it's always busy all the time.

If the filters are getting clogged, the PC may be overheating and locking up. See if a package called Diagbase or Diagmonitor is installed. It should have detailed diagnostics like CPU temps and hard drive status, and it should also have preset ranges for OK/Not OK.
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Old March 20th, 2017, 10:11 AM   #6
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Quote:
Originally Posted by bhedding024 View Post
I actually looked at the CPU usage and it is pegged out nearly all the time by an application called "s7wlpapx.exe" which from what I understand is just basically a tool to keep the PC from going into hibernation.
As far as I understand, this is actually part of WinLC RTX which is the soft PLC.

Definitely look into the diagnostics tools. And open up the cabinet and take a look inside. If it is gunked up or the fans are not rotating you may have found the culprit.
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Old March 20th, 2017, 10:25 AM   #7
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Originally Posted by mk42 View Post
Because the realtime part of the kernel operates outside/below Windows, it doesn't know how much processor is getting used on the realtime side. This means it could either go to sleep or decrease the processing speed to save power. This causes delays/faults/shutdowns on the PLC side, which is obviously undesireable, so the service you mentioned was hacked together to trick Windows into thinking it's always busy all the time.
I dont think so. The RTX extensions are exactly there to make the PLC insensitive to Windows problems. Even if Windows goes completely down, the RTX will continue to operate.

I am sure if the PLC had delays or faults or even shutdowns, bhedding024 would have mentioned that.
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Old March 20th, 2017, 11:06 AM   #8
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I dont think so. The RTX extensions are exactly there to make the PLC insensitive to Windows problems. Even if Windows goes completely down, the RTX will continue to operate.

I am sure if the PLC had delays or faults or even shutdowns, bhedding024 would have mentioned that.
If Windows crashes, RTX keeps running, for sure.

However, if Windows tells the HW to do something like sleep/hibernate or go into a power saving mode, the PC HW does it. Also, I think the powersaving is sometimes done at the HW layer, which might mean it's the CPU itself RTX needs to fake out, not Windows.

I think the new generation Soft PLCs (1507S, etc) protect against this somewhat via the Siemens hypervisor. I think the PLC stays running during a Windows reboot, and it may disable/prevent power saving options. Still, though, if Windows tells the PC HW to shut down, it will, and it takes the PLC with it. This is sometimes done on purpose, for example when a UPS signals it is running low.
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Old March 20th, 2017, 01:30 PM   #9
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Just to clarify, there are no issues with the PLC component of the system. The WinLC RTX application continues to run. The variables on the screen lock up, as does the navigation and such. I also loose the USB keyboard and mouse connected to the HMI.
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