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Siemens SINUMERIK Controller
Servo/Axis · Basic · 15-30 minutes
Siemens 840D 61740 - Channel block: Blank must be closed contour
Alarm triggered by following cycle: CYCLE950. Remedy: Check whether blank contour is closed, i.e. starting point = end point.
61740
Siemens 840D 61740 - Channel block: Blank must be closed contour
Channel block: Blank must be closed contour
Alarm triggered by following cycle: CYCLE950. Remedy: Check whether blank contour is closed, i.e. starting point = end point.
Safety
- Refer to Siemens documentation
- Ensure qualified technician performs repairs
Common Causes
- Blank contour path does not close - starting point coordinates differ from ending point coordinates
- Rounding errors or floating-point precision issues causing slight mismatch between start and end positions
- Missing or incomplete geometry segment in the contour definition within CYCLE950
- Incorrect coordinate input in the part program defining the blank contour boundaries
Troubleshooting Steps
- 1Review the CYCLE950 blank contour definition in the part program and verify that the final point coordinates exactly match the initial point coordinates
- 2Check the part program syntax for the contour - ensure all geometry elements are properly defined and no segments are missing
- 3Compare programmed coordinates against the drawing specifications to confirm the contour path is geometrically closed
- 4If using decimal coordinates, verify precision levels are consistent throughout the contour definition to avoid rounding discrepancies
- 5Reload and re-execute the program after corrections to confirm the contour closure is recognized by the control system
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