Latched Registers and Persistent values

Hi there I was wondering if someone could explain how to keep persistent values even after power loss?

I noticed my predecessor has a runtime counter and uses registers that appear to be "latched".

Does this have anything to do with persistent values?

Sorry to ask so many questions. Hopefully I can start contributing here soon!

im on a DVP-SX2

Thanks!

http://www.deltaww.com/filecenter/Products/download/06/060301/Manual/DELTA_IA-PLC_DVP-ES2-EX2-SS2-SA2-SX2-SE-TP_PM_EN_20170426.pdf

The above manual may help you out.
2.5 Status and Allocation of Latched Memory
The chart will show what is memory retentive on powering the unit or switching from program to run.

Regards,