Code 206010: <location>Infeed: Power unit EP 24 V missing in operation
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>Infeed: Power unit EP 24 V missing in operation 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
Message value: Drive object: A_INF, B_INF, S_INF Reaction: OFF2 (OFF1) Acknowledge: IMMEDIATELY (POWER ON) Cause: In operation, withdraw the pulse enable at te rminal EP at the Line Module (X21.3, X21.4). Remedy: - do not open the Line Side Switch in operation - only when the pulses are inhibited. - check the wiring of the DP input (X21.3, X21.4) at the Line Module to exclude any poor contacts.
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 206010 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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