The Industrial Raspberry Pi Forum

Hi everyone,

When we are using industrial PLC, whenever we plug it off, it will include a mechanism (capacitor, embedded software) to shutdown without corrupting the memory. So when the device is powered on later, we are ensured it will run again. Of course, we

I would like to expect exactly the same from the RevPi Connect+. Let say I have a program running with eMMC write (ie : logging) and the RevPi is plugged off during memory write : how to be sure the memory is not corrupt as an industrial PLC? Is there a hardware (embedded capacitor, wawtchdog...) or software way (filesystem) to act the same as an industrial PLC?

Same question with the hardware watchdog : if it acts as a hard reboot for the RevPi (the SoC powersupply is shut off during 1 second), how to avoid memory corruption?

Many thanks!
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Antoine

Anyone ?

Hi Antoine, well sure a UPS is able to provide a safe way to reboot the device properly. I just can say hat we deal here with may devices every day. We are swiching them on and off without proper shutdown commands at all...
All I can say is that the Ext4 file system works pretty well here as this is a journaling file system.

So you can confirm that proper shutdown is not necessary? I'm looking to use the RevPi Core 3 for connecting to a web site inside my company. I will connect a 7 inch touch screen through micro HDMI and usb port for touch.
Do you think there is no problem shutting down taking out the power?
Thanks a lot
Massimo

Well I cannot guarantee that your systems will never be in such situations where data will be unpredictable losst. There is also a limited eMMC life time depending on the wear leveling etc. So just give it a try.

I'm also thinking about the power-fail safety of the RevolutionPI. How are the experiences from the field applications (customers)? Do you know about problems after power off?
Is there a hardware (capacitor or similar) to finish critical writing processes to the eMMC in case of sudden power off?

I'm thinking about using the RevPi Connect 4 as an IoT Hub inside industrial production machines. Sudden power off could happen daily. Can you recommend me the RevolutionPi for this use case without an UPS?

Hello Matthias, take a look at this FAQ entry: Revolution Pi Hardware FAQ | "Is there a recommendation for a small UPS in DIN rail format?"
We have designed the RevPi Connect for use together with an uninterruptible power supply. See also this article:
How to Connect UPS
The article shows a RevPi Connect 3+ - we are currently working hard to update the documentation - so here is the picture of the front of the RevPi Connect 4
https://revolutionpi.com/tutorials/revp ... -connect-4
From my experience, I can say that I have never had problems with a corrupt file system, even if I simply unplugged the device several times and did not shut it down correctly using the "shutdown" command.
There is quite a lot of discussion material in this direction in the forum if you search for UPS or USV, i.e. here (you have to translate them maybe)

• Einfacher USV Ersatz
• Shutdown Codesys/RevPi bei USV Betrieb
• Stromausfälle und RevPi Core 3: USV erforderlich?

In general, the ext4 file system which is used, i.e. in the current "Bullseye" image is a journaling file system that is robust and simply writes back journal entries that have not yet been synchronized after startup as if nothing had happened. However, there can always be a residual risk that justifies the use of a UPS.