Siemens SINUMERIK codes
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Siemens SINUMERIK Controller

Servo/Axis · Basic · 10-20 minutes

Alarm 12520

Siemens 840D 12520 - Channel block too many tool parameters

In the part program, in the tool offset file (._TOA) and in the initialization file (._INI), no more than 5 tool offset parameters may be used per block. Example: N. N 100 $TC_DP1 [5,1] = 130, $TC_DP3 [5,1] = 150.123, $TC_DP4 [5,1] = 223.4, $TC_DP5 [5,1] = 200.12, $TC_DP6 [5,1] = 55.02 N.

Siemens SINUMERIKServo/AxisBasic10-20 minutes

12520

Siemens 840D 12520 - Channel block too many tool parameters

Channel block too many tool parameters

In the part program, in the tool offset file (._TOA) and in the initialization file (._INI), no more than 5 tool offset parameters may be used per block. Example: N. N 100 $TC_DP1 [5,1] = 130, $TC_DP3 [5,1] = 150.123, $TC_DP4 [5,1] = 223.4, $TC_DP5 [5,1] = 200.12, $TC_DP6 [5,1] = 55.02 N.

Safety

  • Refer to Siemens documentation
  • Ensure qualified technician performs repairs

Common Causes

  • More than 5 tool offset parameters assigned in a single block of the part program, tool offset file (_TOA), or initialization file (_INI)
  • Attempt to modify multiple tool parameters (TC_DP1 through TC_DP6 or higher) in one program line without splitting across multiple blocks
  • Tool offset file or initialization file contains a block with excessive parameter definitions exceeding the 5-parameter limit
  • Complex tool setup routines combining multiple offset parameters in a single NC block without proper segmentation

Troubleshooting Steps

  1. 1Identify the exact block number referenced in the alarm message and locate it in the active part program, _TOA file, or _INI file
  2. 2Count the number of tool offset parameters ($TC_DP#) being assigned in the flagged block; verify the count exceeds 5
  3. 3Split the block into multiple sequential blocks, distributing no more than 5 tool parameters per block, maintaining logical grouping
  4. 4Verify the corrected program syntax uses proper block delimiters (N commands) between parameter assignments
  5. 5Reload the corrected part program or configuration file and restart execution to confirm the alarm clears

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