Code 230851: <location>Power unit DRIVE-CL iQ (CU): Sign-of-life missing
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>Power unit DRIVE-CL iQ (CU): Sign-of-life missing 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, fault cause: %2 Drive object: All objects Reaction: A_INFEED: OFF2 (NONE, OFF1) SERVO: OFF2 (NONE, OFF1, OFF3) VECTOR: OFF2 (NONE, OFF1, OFF3) Acknowledge: IMMEDIATELY Cause: A DRIVE-CLiQ communication error has occurred fr om the power unit to the Control Unit involved. The DRIVE-CLiQ component did not set the sign-of-life to the Control Unit. Fault value (r0949, interpret hexadecimal): yyxx hex: yy = component number, xx = fault cause xx = 0A hex = 10 dec: The sign-of-life bit in the receive telegram is not set. Remedy: Upgrade the firmware of the component involved.
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 230851 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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