Code 201381: <location>Topology: Comparison power unit shifted
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>Topology: Comparison power unit shifted 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: Component number: %1, Component class: %2, Component (target): %3, Connection number: %4 Drive object: All objects Reaction: NONE Acknowledge: NONE Cause: The topology comparison has detected a power unit in the actual topology that has been shifted with respect to the target topology. Alarm value (r2124, interpret hexadecimal): ddccbbaa hex: dd = connection number cc = component number bb = component class aa = component number of the component shifted in the target topology Note: The connection in the actual topology where the shifted component was detected is described in dd, cc and bb. Component class and connection number are described in F01375. The drive system is no longer booted. In this stat e, the drive control (closed-loop) cannot be enabled. SINAMICS-Alarms Diagnostics Manual (DAsl), 03/2009 Remedy: Adapting the topologies: - undo the change to the actual topology by changing over the DRIVE-CLiQ cables. - commissioning software: Go online, upload the dr ive unit, adapt the topology offline and download the modified project. - automatically remove the topology error (p9904). Note: Under "Topology --> Topology view" the commissi oning software offers improved diagnostics capability (e.g. setpoint/actual value comparison).
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 201381 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.
Have a better solution?
Help the industrial community by sharing your repair experience for code 201381.
Need a searchable reference for more Siemens SINUMERIK 840D CNC manuals?
We structure equipment manuals into searchable code, title, cause, solution, safety note, and source-reference data. Send a PDF and example searched codes when you need public pages, private search, or structured exports.
Space reserved for Google AdSense / Industrial Affiliate Links
Monetization target for 2026