Code 1031: Link module generated an un specified error %1 NCU %2 %3 %4
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical Link module generated an un specified error %1 NCU %2 %3 %4 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
Parameters: %1 = Hex-Zahl unspecified status in stateOfLinkModules %2 = NCU number %3 = Command from link module to NCK %4 = Status of own link Definitions: This alarm is not a user error. - 1. If NCU== 0 -> A parameter not equal to zero was not found - 2. If NCU not equal to zero -> An error which the NC was not able to interpret in the connection to this NCU. The error is output as a number. It is pos sible that the NCU link module is running a newer software version than the NC. The other parameters are used for error localization in the NC/LINK-MODUL software. Reaction: NC not ready. Channel not ready. NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm. Remedy: Make a note of the error text and contact Siem ens AG A&D MC, Hotline (tel./fax: see alarm 1000) Program Continuation: Switch control OFF - ON. Diagnostics Manual (DAsl), 03/2009
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 1031 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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