1

I plan to use RPi’s (zero w) to create some potentiometer value readers for the company I work at. They will be used in the production, in order to adjust the potentiometers in some products. The problem is that the RPi’s might be used by people who are not that familiar with how computers work and may simply remove the power from the pi without using the turn off switch that I am going to add. As an extra safety measure I thought of using industrial microSD cards as they are tougher and some are advertised as offering power failure protection. I have read around some good stuff about them but the information I found is not enough.

I would be grateful if someone could suggest some specific brand/model of industrial cards based on experience and good results against power failures. Currently looking at the cards from ATP, SwissBit and Panasonic.

Ps: as a second level protection I am thinking of adding a small ups on every pi as well that triggers a shutdown command.

Thank you!

6
  • Have you thought about making the filesystem read-only? learn.adafruit.com/read-only-raspberry-pi – Unsigned_Arduino Aug 3 '20 at 14:01
  • @Unsigned_Arduino this might also be a good idea. But as I will be adding features constantly in the beginning, it will have to wait until later development stages. – qeiynn Aug 3 '20 at 14:41
  • But it's not going to be released until you finished everything (unless you do beta stuff, then warn the user), so right before you release it, make the FS read-only. – Unsigned_Arduino Aug 3 '20 at 18:54
  • It will be used inside our company as a tool to calibrate potentiometers in the production department. So it will not be a product for sale. This means it might be receiving often updates and new features, as well as adjustments according to the feedback. But once it is in a stable state with enough features I think making it read only is a great idea. Thanks again for the tip. – qeiynn Aug 3 '20 at 20:32
  • Oh, sorry for mis-reading the question. Good luck! – Unsigned_Arduino Aug 4 '20 at 23:03
1

The issue is not normally the destruction of the card (I've used normal ones in -16C) but the actually data or OS file system being corrupted by not being written to the card as the machine dies due to the environment.

I used to handle over 70 different bits of kit in the field that where mission critical and had to handle temperatures of +40C down to -35C (excluding wind chill) with temperature changes of 50+C in seconds.

You would do better (esp as this site is not really for purchase recommendations) to look at:

  1. Heat / Cold ingress
  2. Removal of condensation risk (big big issue)
  3. How external devices (i.e. ANYTHING plugged into the PI) are sealed / connected
  4. Accuracy and control of power
  5. PREVENTIVE maintenance of equipment inc cases, connectors, SD cards, power supplies etc
  6. REGULAR maintenance of hardware and application programs

From an OS and application point of view:

  1. Do you freeze at one version (inc ALL tools / libraries)
  2. How do you do critical security updates if not
  3. How do you check updates BEFORE putting them in the field
  4. How do you handle application updates / change control
  5. Resiliency of programs to user input and errors

From a data issue, you need to consider:

  1. Impact of cache at application / operating system and hardware level
  2. Impact and recovery of database write failures
  3. Possibly journal of database / data writes
  4. Recovery of systems post power loss AND power brown-out

Save your money - it will cost more to fix and manage the above that will impact you before a card does.

Remember: Machinery is built with safe guards to keep people alive - Pi computers and your average case is not and steps must be taken to make sure any that could fail, fails safe as peoples lives could be at risk.

Not the answer you're looking for? Browse other questions tagged or ask your own question.