Code 4002: [Channel %1: ] Machine data %2[%3] assigns an axis not defined in channel
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Machine data %2[%3] assigns an axis not defined in channel alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
Parameters: %1 = Channel number %2 = String: MD identifier %3 = Index: MD array index Definitions: Only axes that have been activat ed in the channel by means of MD20070 $MC_AXCONF_MACHAX_USED [kx]=m may be declar ed as geometry axes or transformation axes by means of the MD20050 $MC_AXCONF_GEOAX_ ASSIGN_TAB [gx]=k. This also applies to MD22420 $MC_FGROUP_DEFAULT_AXES (gx: Geometry axis index, kx: Channel axis index, k: Channel axis no., m: Machine axis no.). Assignment of geometry axes to channel axes MD20050 $MC_AXCONF_GEOAX_ASSIGN_TAB (includes channel axis no. k): - Geometry axis index: 0, 1st channel: 1, 2nd channel: 1 - Geometry axis index: 1, 1st channel: 2, 2nd channel: 0 - Geometry axis index: 2, 1st channel: 3, 2nd channel: 3 Diagnostics Manual (DAsl), 03/2009 MD20070 $MC_AXCONF_MACHAX_USED (includes machine axis no. m): - Channel axis index: 0, 1s t channel: 1, 2nd channel: 4 - Channel axis index: 1, 1s t channel: 2, 2nd channel: 5 - Channel axis index: 2, 1s t channel: 3, 2nd channel: 6 - Channel axis index: 3, 1s t channel: 7, 2nd channel: 0 - Channel axis index: 4, 1s t channel: 8, 2nd channel: 0 - Channel axis index: 5, 1s t channel: 0, 2nd channel: 0 - Channel axis index: 6, 1s t channel: 0, 2nd channel: 0 - Channel axis index: 7, 1s t channel: 0, 2nd channel: 0 Reaction: NC not ready. Mode group not ready, also effective for single axes NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm. Remedy: Please inform the authorized personnel/service department. Correct - MD20050 $MC_AXCONF_GEOAX_ASSIGN_TAB - MD24... $MC_TRAFO_AXES_IN_... - MD24... $MC_TRAFO_GEOAX_ASSIGN_TAB_... - MD22420 $MC_FGROUP_DEFAULT_AXES - and/or MD20070 $MC_AXCONF_MACHAX_USED. Program Continuation: Switch control OFF - ON.
Source: SINUMERIK 840D sl / 840Di sl / SINAMICS S120 Diagnostics Manual (DAsl, 03/2009)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Siemens SINUMERIK 840D CNC Alarms
Siemens controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code 4002 on the SINUMERIK 840D CNC identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Siemens's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 4014 Siemens SINUMERIK 840D CNC codes.
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