26031

Access SINUMERIK HMI > Parameters > Machine Data > Axis-Specific (MD 3xxxx series) and locate the coupling configuration block (typically MD 32000-32099 range for master definition and MD 32100-32199 for slave definition).

Do not modify parameters while machine is in AUTO mode or with active G-code execution.

Verify that the axis name in MD 32000 (MASTER_AXIS_NUMBER) differs from the axis name in MD 32100 (SLAVE_AXIS_NUMBER) for the affected coupling. Cross-reference against the axis declaration in MD 1008 AXISTYPES_CONFIGURED.

If self-reference is found, correct the slave axis parameter to the intended dependent axis. If both parameters reference the same physical axis, disable one coupling definition entirely or restructure the kinematic chain.

Recalculate gear ratios (MD 32110 GEAR_RATIO) and offset compensation after correcting axis assignment.

Save parameters, perform a warm restart (Ctrl+Shift+Del or NCK > Startup > Warm Restart), and verify alarm 26031 clears during axis initialization sequence.

Navigate to NCK > Diagnosis > Axis Info and review the 'Coupling Status' field for the alarm-triggering axis. Note which coupling group it reports and check if bidirectional relationships are shown.

In the PLC editor or SAM configuration, search for all instances of the axis name in coupling-related function blocks (e.g., FB_AxisCoupling, MC_MASTER, MC_SLAVE calls). Confirm each axis appears in only one role per coupling instance.

Backup PLC source before modifying; changes require full recompilation and download.

Check SD (SetUp Data) parameters related to axis selection, particularly SD 42710 AXISSELECT_FOR_COUPLING if your system uses dynamic coupling assignment.

Recompile the PLC program, download it to the control, and execute a full system restart (warm restart or power cycle) to reload coupling configuration from both NCK Machine Data and PLC logic.

Access MD 1009 AXIS_NAME_TAB and MD 1010 SPINDLE_NAME_TAB, then cross-reference all axis identifiers used in coupling parameters (MD 32000/32100) to ensure no aliases or duplicates map to the same physical hardware.

In multi-channel systems, verify that each channel's local axis configuration (if present) does not redefine the same physical axis with a different name, causing the parser to treat it as a new axis in the coupling link.

Document the authoritative axis naming scheme in your configuration and ensure all Master Data references (MD), SetUp Data (SD), and PLC variables use consistent nomenclature.

Clear any cached axis definitions and re-initialize the NCK via Menu > System > Reset NCK or perform a full power-on reset to reload all axis identity definitions.