Code 702506: Wire breakage, analog sensor! Tool unclamped spindle 1
Issue Description & Safety Warning
The Chiron Siemens-Control CNC has triggered a critical Wire breakage, analog sensor! Tool unclamped spindle 1 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
PLC input signal "Tool unclamped" is not registered. Actual current value of the analogue sensor lies below 4 mA. This means wire breakage. The error has the following effect: Feed Stop No axis movements possible. "Spindle Stop" Tool spindle is stopped. Speed no longer possible. 1. Check "Tool unclamped" sensor and the associated PLC input signals. 2. Check the value of the current of the analogue sensor. 3. As soon as the malfunction has been remedied, press [FEED START] or [CYCLE START]: Message is cleared. Error messages Tool change Wire breakage, analog sensor! Tool unclamped spindle 1
Source: CHIRON Error Message Overview, all series (Siemens control, V2.0.6, 2012)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Chiron Siemens-Control CNC Alarms
Chiron controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code 702506 on the Siemens-Control CNC identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Chiron's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 545 Chiron Siemens-Control CNC codes.
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