Code 21620: [Channel %1: ] Axis %2 Emergency braking ramp activated
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Axis %2 Emergency braking ramp activated 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 = Channel number %2 = Axis name, spindle number Definitions: The axial emergency braking ramp has been ac tivated for the specified axis/spindle The following causes are possible for ac tivation of the emergency braking ramp: Alarm 26052: Path velocity for auxiliary function output too high Alarm 1012: System error with ID 550006 Alarm 1016: System error with ID 550003, 550005 and 550010 Context-sensitive braking reques t with priority 13 is active Reaction: NC Start disable in this channel. Local alarm reaction. The NC switches to follow-up mode. Interface signals are set. Alarm display. Remedy: Please inform the authorized pers onnel/service department. Remove or reset the cause of the alarm. Program Continuation: Clear alarm with the RESET key. Restart part program
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 21620 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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