Code 201425: <location>Topology: Comparison serial number of a component is different
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>Topology: Comparison serial number of a component is different 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, Differences: %3 Drive object: All objects Reaction: NONE Acknowledge: NONE Cause: The topology comparison has detected differences in the actual and target topologies in relation to one component. The serial number is different. Alarm value (r2124, interpret hexadecimal): ddccbbaa hex: cc = number of differences bb = component class aa = component number of the component Note: The component class is 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: - change over the actual topology to match the target topology. - download the target topology that matches the actual topology (commissioning software). Re byte cc: cc = 1 --> can be acknowledged using p9904 or p9905. cc > 1 --> can be acknowledged using p9905 and can be de-activated using p9906 or p9907/p9908. Note: Under "Topology --> Topology view" the commissi oning software offers improved diagnostics capability (e.g. setpoint/actual value comparison). See also: p9904, p9905, p9906, p9907, p9908
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 201425 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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