What causes Heidenhain alarm 1C7-0268?

Encoder cable damaged, pinched in cable carrier, or connector loose or corroded. Linear scale or rotary encoder reading head contaminated with coolant, chips, or oil mist. Encoder supply voltage out of specification causing degraded signal output. EnDat or 1Vpp signal amplitude below the TNC monitoring threshold. Encoder reading head misaligned or physically damaged. Encoder hardware failure — signal processing electronics or scale damage.

How do I fix Heidenhain alarm 1C7-0268?

1. Inspect the encoder cable along its full length for damage — check cable carrier sections particularly. 2. Reseat encoder connectors at both the encoder head and TNC control unit ends. 3. Clean the linear scale or rotary encoder reading surface and head with a lint-free cloth. 4. Check encoder supply voltage at the connector with a multimeter. 5. Use the Heidenhain TNC encoder diagnostic screen to check signal amplitude. 6. Replace the encoder cable first; replace the reading head if the cable checks out.

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Heidenhain Controller

Servo/Axis · Intermediate · 30-120 minutes

Alarm 1C7-0268

Heidenhain 1C7-0268 - Permit handwh. superimposition of rotary axes only with TCPM

Alarm 1C7-0268 occurs when attempting to use handwheel superimposition on rotary axes without TCPM (Tool Center Point Management) active. The TNC system requires TCPM to be enabled for safe handwheel operation on rotary axes to maintain proper tool tip positioning.

HeidenhainServo/AxisIntermediate30-120 minutes

1C7-0268

Heidenhain 1C7-0268 - Permit handwh. superimposition of rotary axes only with TCPM

Permit handwh. superimposition of rotary axes only with TCPM

Root Cause Summary

Alarm 1C7-0268 occurs when attempting to use handwheel superimposition on rotary axes without TCPM (Tool Center Point Management) active. The TNC system requires TCPM to be enabled for safe handwheel operation on rotary axes to maintain proper tool tip positioning.

Safety

Refer to Heidenhain service manual
Ensure qualified technician performs repairs

Causes and Fixes

1
Check TCPM machine parameter
Access MOD function, enter machine parameters, check MP7440 TCPM_FUNCTION. Value must be 1 or 2 for TCPM activation.
MP7440=1 enables basic TCPM, MP7440=2 enables extended TCPM with additional compensation
2
Verify rotary axis configuration
Check MP7441-MP7443 for rotary axis assignment and MP7444-MP7446 for axis vector definitions.
Incorrect axis vectors can cause collision during TCPM operation
3
Activate TCPM and test
Set MP7440=1, perform control restart, then test handwheel operation on rotary axes in Manual mode.
Use M128 in program to activate TCPM or PLANE SPATIAL for automatic activation

DIY Feasiblehigh confidence

Call a technician if:

·Kinematic parameters unknown or machine documentation unavailable
·TCPM activation causes unexpected machine behavior
·Rotary axis mechanical issues suspected

Prevention

Always verify TCPM status before rotary axis handwheel operation
Include M128 in program headers for 5-axis operations
Regular verification of kinematic parameters during maintenance

Common Mistakes

Attempting rotary handwheel operation without TCPM
Forgetting M129 deactivates TCPM for subsequent operations
Incorrect kinematic parameter entry during setup

Related Alarms

1C7-0267 1C7-0269 1C7-0350

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