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Siemens SINUMERIK Controller
Servo/Axis · Intermediate · 20-45 minutes
Siemens 840D 16954 - Channel block programmed stop prohibited in stop delay area
In a program area (stop delay area) that is bracketed with DELAYFSTON and DELAYFSTOF, a program command was used that causes a stop. No commands other than G4 are permissible that might cause a stop even though only shortly. A stop delay area can also be defined by $MN_STOP_MODE_MASK.
16954
Siemens 840D 16954 - Channel block programmed stop prohibited in stop delay area
Channel block programmed stop prohibited in stop delay area
In a program area (stop delay area) that is bracketed with DELAYFSTON and DELAYFSTOF, a program command was used that causes a stop. No commands other than G4 are permissible that might cause a stop even though only shortly. A stop delay area can also be defined by $MN_STOP_MODE_MASK.
Safety
- Refer to Siemens documentation
- Ensure qualified technician performs repairs
Common Causes
- M0, M1, or M2 command executed within DELAYFSTON/DELAYFSTOF bracketed section
- Program stop or optional stop command issued in stop delay protected area
- Improper nesting or unclosed DELAYFSTON/DELAYFSTOF blocks allowing stop commands in protected zones
- Stop delay area defined by $MN_STOP_MODE_MASK parameter contains incompatible stop commands
- Feed hold or spindle stop logic triggered within stop delay area that halts axis motion
Troubleshooting Steps
- 1Review NC program listing between DELAYFSTON and DELAYFSTOF commands; identify and remove or relocate any M0, M1, M2, or similar stop-causing commands outside the protected area
- 2Verify DELAYFSTON/DELAYFSTOF block structure is properly nested without overlap; confirm matching pairs and correct sequencing in program flow
- 3Check $MN_STOP_MODE_MASK parameter definition in machine data to confirm stop delay area boundaries; compare against program structure and remove conflicting stop commands from defined zones
- 4Replace prohibited stop commands with G4 dwell commands if brief pause is required within stop delay area, as G4 is the only permissible motion control command in these zones
- 5Clear alarm, reload corrected program, and perform single block test run to verify no stop commands execute within protected areas
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