Code 20074: [Channel %1: ] Axis %2 wrong index position
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Axis %2 wrong index position 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 name, spindle number Definitions: For a concurrent positioning axis declared as indexing axis, the PL C has given an index number that is not available in the table. Reaction: Alarm display. Remedy: Please inform the authorized personnel/service departm ent. Check the indexing axis number given by the PLC and correct this if necessary. If the indexing axis number is correct and the alarm results from an indexing position table that has been set too sh ort, check the machine dat a 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 20074 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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