If the above steps do not resolve the issue, advanced troubleshooting may be required:
Remove the battery (Type: Lithium 3.6V, usually ½ AA or AA). Measure it with a voltmeter.
The SINUMERIK 810D is an advanced, compact CNC system from Siemens that integrates the core numerical control (NCK), the programmable logic controller (PLC), and the drive control for the motors into a single hardware unit known as the CCU (Compact Control Unit). The error message appears on the Human-Machine Interface (HMI) when this unit fails to establish communication with the display panel.
If the screen stubbornly remains on "Waiting for NCK Connection," you may need to force a reset. On the CCU unit (usually integrated into the drive module), there is a reset button or a toggle switch (often labeled S1 or S3 depending on the revision).
After 20+ years, capacitors dry out and chips fail. sinumerik 810d waiting for nck connection
Step 4: Perform a Complete NCK and PLC Clear (Reset Procedure)
In some cases, the issue is not data loss but a genuine hardware problem. This could include a failed CCU module, a corrupted PCMCIA memory card, or a faulty communication cable between the CCU and the HMI device (PCU20/PCU50). The LED indicators on the front of the CCU provide crucial diagnostic information—for instance, a lit SF (red) light indicates a drive-related fault or a more serious CCU issue.
The system also utilizes the PLC (Programmable Logic Controller) to handle logic functions like limit switches, coolant, and tool changers. All machine-specific data, including configuration, parameters, and user programs, are stored in battery-backed RAM (Random Access Memory) on the CCU (Compact Control Unit), which houses the NCK. This type of memory loses all data if power is interrupted and there is no backup battery.
Always start with the NCU’s LEDs and 7-segment display. Do not touch the HMI first. By methodically verifying power, battery voltage, and bus communication, you can diagnose the fault in under 15 minutes. If the above steps do not resolve the
Sometimes, the machine just gets "confused" during the boot sequence. The PLC starts, the HMI starts, but the NCK hangs.
Release the switch, then immediately turn it back to for another second. The STOP LED should flash rapidly, indicating the memory wipe is active.
"It’s stuck in a loop," Elias muttered, gesturing to the screen. "I’ve cycled the power thrice. Checked the cables. The PLC status LEDs are green, but the HMI just won't bridge the gap."
If you are experiencing this issue, it is crucial to address it promptly to minimize production downtime. Perform basic troubleshooting steps, and if the issue persists, consider seeking support from Siemens or a qualified technician to ensure optimal system performance. The error message appears on the Human-Machine Interface
The machine let out a soft, mechanical sigh as the cooling fans kicked into high gear.
Verify that the assigned OPI address for the HMI matches the physical address configured on the CCU (the standard default address for the NCK is typically 2 , and the HMI is typically 1 or 6 ).
Solid red means the PLC has stopped running, often due to a hardware fault or a logic error in the step program.
Before swapping hardware or changing software settings, check the physical status LEDs on the front face of the Sinumerik 810D CCU module. These lights provide immediate diagnostic feedback regarding the state of the internal hardware. Normal Operating State