Code 207800: <location>Drive: No power unit present
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>Drive: No power unit present 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, SERVO, VECTOR Reaction: NONE Acknowledge: IMMEDIATELY Cause: The power unit parameters cannot be read or no parameters are stored in the power unit. Connection between the Control Unit and the Motor Module was interrupted or is defective. This fault also occurs if an incorrect topology was selected in the commissioning software and this parameterization is then downloaded to the Control Unit. See also: r0200 (Power unit current code number) Remedy: - connect the data line to power unit and restart the Control Unit (POWER ON). - check or replace the Control Unit. - check the cable between the Control Unit and Motor Module. - after correcting the topology, the parameters must be again downloaded using the commissioning software.
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 207800 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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