Applicable Systems
SINUMERIK 840D
SINUMERIK 840D sl
SINUMERIK 840Di
SINUMERIK ONE
Symptoms
The deceleration switch signal was not detected during zero return. Possible causes: switch fault, wiring error, wrong return direction, or PLC address error.
Possible Causes
- Drive-CLiQ communication cable loose or damaged
- Drive module power supply fault
- Drive module hardware damage
- NCU motherboard fault
- Parameter setting error
- Mechanical overload or binding
- Encoder feedback fault
Troubleshooting Steps
- Step 1: Record the alarm code and all displayed messages from the HMI
Complete alarm information captured - Step 2: Check the Drive-CLiQ cable connections between NCU and drive modules
All cables are securely connected and undamaged - Step 3: Verify the drive module power supply and LED status
Drive module LEDs show normal (green) status - Step 4: Use the diagnostic menu (DIAGNOSIS) to view NC and PLC alarms
All active alarms are identified - Step 5: Address the root cause identified in the diagnostics
Root cause is resolved
How to Reset
To reset SINUMERIK 840D alarm 21000: 1) Fix the root cause identified in diagnostics. 2) Press the RESET key on the MCP (Machine Control Panel). 3) If alarm persists, power cycle the machine. 4) If hardware fault, replace the faulty component. Caution: Some alarms require specific reset sequences; consult the 840D diagnostics manual.
Frequently Asked Questions
- Q: What does 21000 mean on Siemens Sinumerik SINUMERIK 840D/840D sl?
The deceleration switch signal was not detected during zero return. Possible causes: switch fault, wiring error, wrong return direction, or PLC address error.
- Q: How do I fix 21000 on Siemens Sinumerik?
Follow the troubleshooting steps: Record the alarm code and all displayed messages from the HMI
Source: Siemens SINUMERIK 840D Diagnostics Manual (blog.csdn.net)
Category: CNC