Note
?Only Insert or replace the battery while the PLC is switched on. Otherwise, an
"OVERALL RESET" is required after POWER ON.
?The S5-90U has no battery low LED.
If the S5-90U is briefly (approx. 20 ms to 10 s) in the POWER OFF state and no
battery back-up is provided, the PLC cannot recognize whether a backup battery is
available during the next restart.
Program data might be falsified in this way. You can help avoid a failure of the
battery back-up by regularly replacing the battery every year.
?A yellow LED on the operator panel of the S5-95U signals a failure of the back-up
battery.