Code 700121: Prox. switch toolchanger up/down
Issue Description & Safety Warning
The Chiron Siemens-Control CNC has triggered a critical Prox. switch toolchanger up/down 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
The "Tool changer up" sensor and the SW cam [10] "Z-axis tool change position up" (F71.1) signal simultaneously (sensor monitor). The machine functions are stopped immediately. As far as no thread-cutting is pending. 1. Check the sensor and the PLC input signal "Tool changer up". 2. Check the SW cam [10] "Z-axis tool change position up" (F71.1). 3. Once the malfunction has been remedied, press [DELETE ERROR] key. Message is cleared. The diagnosis overview of the signals can be found under: Error messages Tool change Prox. switch toolchanger up/down Chapter 2.2 ‘Tool changer diagnostics menu’ on page 11
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 700121 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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