Code 206901: <location>Braking Module: Pre-alarm I2t shutdown
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>Braking Module: Pre-alarm I2t shutdown 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: A_INF, B_INF, S_INF Reaction: NONE Acknowledge: NONE Cause: The Braking Module signals "Pre-alarm I2t shutdown" via terminal X21.3. This signal is interconnected via binector input p3865[0...7]. Note: The pre-alarm I2t shutdown is only possible for " booksize" formats. This function is not supported for "chassis" formats. Remedy: - reduce the number of braking operations. - check binector input BI: p3865[0...7] and the wiring fr om terminal X21.3 of the particular Braking Module.
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 206901 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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