To my knowledge I think you should use retentive memory or data blocks. You can store your calibrated values in DB s or in retentive memory ranges.

For change retentive M range go to hardware setting (Off line) and go to properties of CPU, then go to retentive memory tab. After that you can change the memory areas an DBs as retentive.

When you do that the memory 0f retentive areawill stay after power cuts.

See the attachment

I think this will help you