firstly find out why?
is the memory backup battery dead? see picture attatched.
is the control a 480/481?
anyone else that has an old biesse: these are getting old now. change the battery before you lose the memory too
(put the new battery on in parallel first, before removing old battery. that way you wont lose memory while changing it!)
its located on inside of controller frame.
use long wires like the original so when corosion starts it has a long way to go before getting to the circuit boards. (dreaded blackwire corrosion is a killer of chips)