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Siemens SINUMERIK Controller
Servo/Axis · Intermediate · 30-120 minutes
Siemens 61221 - Block : No tool active
Alarm 61221 fires when the NCK attempts to execute a machining block (G01, G02, G03, G05, drilling, etc.) without an active tool selected via T-word or tool offset activation. This is a prerequisite check in the SINUMERIK 840D interpreter that prevents motion commands from executing in an undefined tool state, protecting against collision and part damage.
61221
Siemens 61221 - Block : No tool active
Block: No tool active
No tool active Control reaction: Interpreter stop NC Start disable in this channel. Interface signals are set. Alarm display.
Root Cause Summary
Alarm 61221 fires when the NCK attempts to execute a machining block (G01, G02, G03, G05, drilling, etc.) without an active tool selected via T-word or tool offset activation. This is a prerequisite check in the SINUMERIK 840D interpreter that prevents motion commands from executing in an undefined tool state, protecting against collision and part damage.
Safety
- Only qualified personnel should diagnose and clear control alarms; follow the machine builder's safety procedures and lockout/tagout where hardware work is required.
Causes and Fixes
- 1
Review the NC program listing around Block %2. Verify a T-word and M06 (or equivalent tool change command per MD 32210) precedes the current block by at least one block.
Check if T0 (tool unload) was issued before the offending block without a subsequent tool selection.
- 2
Confirm tool offset activation: verify D-word is specified with the T-word. Check MD 32100 (tool management basic mode) and SD 42410 (active tool number) to see if tool is registered.
- 3
Navigate to Diagnostics > Machine Data > 32000 (Tool Management) group. Verify MD 32210 is configured correctly for your tool changer type (e.g., ATC behavior, M06 vs. direct assignment).
- 4
Insert a T-word with valid tool number and M06 in the program before the offending block. Example: T1 M06 ; (Load tool 1 and execute tool change).
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