Code 206905: <location>Braking Module internal I2t shutdown alarm
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>Braking Module internal I2t shutdown alarm 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: %1 Drive object: B_INF Reaction: NONE Acknowledge: NONE Cause: The internal Braking Module outputs an alarm due to the high I2t value. 80% of the maximum switch-on duration of the braking resistor has been reached. Note: This message is also displayed via BO: p3685. See also: r3685 (Digital Braking Module: Pre-alarm I2t shutdown) Remedy: Reduce the number of braking operations.
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 206905 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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