The NCK and PLC rely on a back-up battery to retain data during power-off periods. If this battery dies, the NCK may lose its system variables or machine data, preventing it from booting correctly. This often results in the NCK stuck in a cyclic reboot or a "Stop" state. Diagnostic Steps and Resolution
NCK booting... DRAM test: PASS Backplane sync: ACQUIRED Axis module 1..6: FOUND Spindle encoder: FOUND Loading OEM parameters from SRAM backup... CHECKSUM FAIL. USING DEFAULTS. sinumerik 810d waiting for nck connection
: Battery failure often causes the CCU to lose its NCK and PLC parameters, leaving it unable to boot into a functional state. The NCK and PLC rely on a back-up
The display should count up from 0 to 6 (or A to F depending on firmware) and settle on a steady green "6" (or "0" or "8" – consult your manual). If it freezes on "1" or "4", the NCK is halted in hardware initialization. Diagnostic Steps and Resolution NCK booting