Code 230074: <location>Communications er ror to the power unit module
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>Communications er ror to the power unit module 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: All objects Reaction: NONE Acknowledge: IMMEDIATELY Cause: Communication is not possible with the power unit via the plug contact. Remedy: The following applies for CU31x and CUA31: Either replace the CU board or the power unit. You must check which of the two components must be replaced by replacing one and then the other com ponent; if neither are available then both components must be returned.
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 230074 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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