Code 10722: [Channel %1: ] Block %5 axis %2 software limit switch %6 violated, residual distance: %7 %3<ALUN> violated
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Block %5 axis %2 software limit switch %6 violated, residual distance: %7 %3<ALUN> violated 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 %3 = Unit of distance %4 = Block number, label|number+s tring(+/-)|residual distance Diagnostics Manual (DAsl), 03/2009 Definitions: The path programmed for the axis violates the currently valid software limit switch. The alarm is activated when preparing the part program block. This alarm is issued instead of alarm 10720 if bit 11=1 in the MD11411 $MN_ENABLE_ALARM_MASK. Alarm 10722 offers an expanded diagnostics option for the software limit switch violation. The condition for activation is the presence of the ALUN* alarm file in the HMI. See also diagnostics guide for alarm 10720. Reaction: Correction block is reorganized. Local alarm reaction. Interface signals are set. Alarm display. Remedy: Check and correct positions in the NC program. Please inform the authorized personnel/service department. Machine data: MD36100 $MA_POS_LIMIT_MINUS/MD36120 $MA_POS_LIMIT_MINUS2 and MD36110 $MA_POS_LIMIT_PLUS/MD36130 $MA_POS_LIMIT_PLUS2 must be checked for the software limit switches. Check the axis-specific interface signals: DB31,... DBX12.3 / 12.2 (2nd software limit switch plus/minus) to see whether the 2nd software limit switch is selected. Check currently active work offsets via the current frame. Work offsets, overlaid movements ($AA_OFF), DRF and transformation components must also be checked. Program Continuation: Clear alarm with NC ST ART or RESET key and continue the 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 10722 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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