Code 10723: [Channel %1: ] Block %5 axis %2 software limit switch %6 violated, residual distance: %7 %3<ALUN>
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> 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 Definitions: The motion planned for the axis violates the currently active software limit switch. The alarm is activated during the preproce ssing of approach or rest blocks for REPOS. This alarm is issued instead of alarm 10721 if bit11=1 in MD11411 $MN_ENABLE_ALARM_MASK. Alarm 10723 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 the Diagnostics Manual for alarm 10721. Reaction: Local alarm reaction. Interface signals are set. Alarm display. Remedy: Determine the cause of the offset from the initial or target position. The REPOS command is executed at the end of an ASUB or system ASUB. See also cross reference from ASUBs. Please inform the authorized personnel/service department. Check the MD36100 $MA_POS_LIMIT_MINUS / MD36120 $MA_POS_LIMIT_MINUS2 and MD36110 $MA_POS_LIMIT_PLUS / MD36130 $MA_POS_LIMIT_PLUS2 for the software limit switches. Check the axis-specific interface signals DB31,... DBX12.3 / 12.2 (2nd software limit switch plus/minus) to see whether the 2nd software limit switch is selected. Check the currently active work offset via the current frame. Also check the external work offsets, overlaid movements ($AA_OFF), DRF and transformation components. Cancel the NC program with NC reset. 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 10723 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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