Code 120400: The settings for the acyclic links with the drive units are not yet effective.%nSwitch off/on HMI !
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical The settings for the acyclic links with the drive units are not yet effective.%nSwitch off/on HMI ! 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
Definitions: A file transfer from/to a drive unit has failed as the settings for acyclic links wi th the drive units become effective only after an HMI reboot. Reaction: Alarm display. Remedy: Switch off/on HMI and then repeat the process leading to the alarm. Program Continuation: Internal
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 120400 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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