Siemens SINUMERIK codes
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Siemens SINUMERIK Controller

Servo/Axis · Basic · 10-20 minutes

Alarm 12070

Siemens 840D 12070 - Channel block too many syntax-defining G functions

Syntax defining G functions determine the structure of the part program block and the addresses contained in it. Only one syntax defining G function may be programmed in each NC block. The G functions in the 1st to 4th G group are syntax defining.

Siemens SINUMERIKServo/AxisBasic10-20 minutes

12070

Siemens 840D 12070 - Channel block too many syntax-defining G functions

Channel block too many syntax-defining G functions

Syntax defining G functions determine the structure of the part program block and the addresses contained in it. Only one syntax defining G function may be programmed in each NC block. The G functions in the 1st to 4th G group are syntax defining.

Safety

  • Refer to Siemens documentation
  • Ensure qualified technician performs repairs

Common Causes

  • Multiple G functions from groups 1-4 programmed in the same NC block
  • G code syntax error where incompatible G functions are combined on one line
  • Incorrect block structure with overlapping motion or plane selection commands
  • Copy-paste error or manual code entry mistake combining conflicting G codes
  • CAM post-processor misconfiguration generating malformed G code output

Troubleshooting Steps

  1. 1Identify the specific block number referenced in the alarm message and review the NC code for that block
  2. 2Separate any G functions from groups 1-4 that appear in the same block into individual consecutive blocks
  3. 3Verify that only one motion command (G0, G1, G2, G3), one plane selection (G17, G18, G19), one feed mode (G93, G94, G95), and one distance mode (G90, G91) exist per block
  4. 4Check the CAM post-processor settings if code is generated automatically and adjust to enforce single G-function-per-block rule
  5. 5Re-run a syntax check or dry run after correcting the block structure to confirm the alarm is cleared

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