Code 21614: [Channel %1: ] Axis %2 hardware limit switch %3
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Axis %2 hardware limit switch %3 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 = String (+, - or +/-) Definitions: The signal DB31,... DBX12.1 / 12.0 (Hardware limi t switch plus/minus) has been set at the NC/PLC interface. Reaction: NC Start disable in this channel. Alarm display. Remedy: Please inform the authorized personnel/service department. 1. With axes that have already been referenced, th e software limit switch 1 or 2 should respond before the hardware limit switch is reached. Check MD36110 $MA_POS_LIMIT_PLUS, MD36100 $MA_POS_LIMIT_MINUS, MD36130 $MA_POS_LIMIT_PLUS2 and MD36120 $MA_POS_LIMIT_MINUS2 and the NC/PLC interface signal for the selection DB31,... DBX12.3 / 12.2 (1st/2nd software limit switch plus/minus) and correct, if nec essary (PLC user program). 2. If the axis has not yet been referenced, it is possi ble to depart from the hardware limit switch in the opposite direction in JOG mode. 3. Check the PLC user program and the connection fr om the switch to the PLC input module, provided the axis has not reached the har dware limit switch at all. 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 21614 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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