My Beaver Partmaster CNC Mill is controlled by a TNC355 Heidenhain controller. The internal parameters and setting are held in memory made 'non volatile' by three AA batteries deep in the bowels of the machine.
The book advice is to change them every year, so to remind me I have a label on the machine "Batteries Changed dd/mm/yyyy" and it works out that around Christmas the batteries indeed get changed, and the removed (but probably still OK for non essential applications) batteries get distributed for grand children's toys.
To my absolute horror I just noticed that the label tells me they were changed in December 2018
![:bugeye:](https://madmodder.net/Smileys/default/confused0068.gif)
I must have been too involved in other things!
So this evening I powered the machine up (batteries get changed with power ON) and was presented with the error "EMERGENCY STOP DEFECTIVE" and nothing would clear it - argh !
Have I lost the parameters? Well no because if that happens it comes up and speaks in German - do the sensible thing - power off - say a prayer to the machine gods, power it back on. Phew - fault cleared. Quick, change those batteries, re-print another label AND DON'T FORGET NEXT TIME !
A close shave but I got away with it - phew.
(I do have all the parameters both as hard copy, paper tape, floppy disk, DVD and on a PC so I'm covered but it's a pain reloading them)