Code 20072: [Channel %1: ] Axis %2 is not an indexing axis
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Axis %2 is not an indexing axis 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 = Axis number Definitions: The displayed axis is operated as a concurrent positioning axis. Its ta rget position is parameterized in the FC INDEX-AXIS as indexing position number, but the axis is not an indexing axis. Reaction: Alarm display. Diagnostics Manual (DAsl), 03/2009 Remedy: Please inform the authorized personnel/service depar tment. The FC POS-AXIS for linear and rotary axes should be used or the axis should be declared as an indexi ng axis. Corresponding machine data for indexing axis declaration: Modify MD30500 $MA_INDEX_AX_ASSIGN_POS_TAB Modify MD10900 $MN_INDEX_AX_LENGTH_POS_TAB_1 Modify MD10910 $MN_INDEX_AX_POS_TAB_1 Modify MD10920 $MN_INDEX_AX_LENGTH_POS_TAB_2 Modify MD10930 $MN_INDEX_AX_POS_TAB_2 Program Continuation: Alarm display showing cause of alarm disapp ears. No further operator action necessary.
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 20072 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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