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Heidenhain Controller
Servo/Axis · Intermediate · 30-120 minutes
HEIDENHAIN 231-C770 - C770 System errors when activating a drive 1
This alarm specifically occurs when the TNC's drive activation handshake fails at the system level, distinguishing it from simple position lag or following errors. The root cause is typically a hardware fault condition present in the encoder, inverter, or enable circuit that blocks the drive from transitioning to the enabled state. Unlike motion-related alarms, this is a pre-operational failure during the enable phase.
231-C770
HEIDENHAIN 231-C770 - C770 System errors when activating a drive 1
C770 System errors when activating a drive 1
A system error occurred while activating a drive. The drive being switched on is either set inactive in the kinematics configuration, or its parameterization has not been completed.
Root Cause Summary
This alarm specifically occurs when the TNC's drive activation handshake fails at the system level, distinguishing it from simple position lag or following errors. The root cause is typically a hardware fault condition present in the encoder, inverter, or enable circuit that blocks the drive from transitioning to the enabled state. Unlike motion-related alarms, this is a pre-operational failure during the enable phase.
Safety
- Refer to Heidenhain service manual
- Ensure qualified technician performs repairs
Causes and Fixes
- 1
Access Encoder Test Function
Navigate to Test -> Encoder Test (or MOD 9-1 depending on TNC version). Select the affected axis and observe encoder status during initialization.
Watch for intermittent EnDat errors during temperature changes - cable routing near heat sources can cause this.
- 2
Check Encoder Error Memory
In the Encoder Test screen, check the EnDat error memory registers. Look for Error Bits in positions 0-7 (especially bits 0-4 for position value errors or bit 5 for temperature warnings).
Do not clear encoder errors until documenting them - they may indicate cable damage or encoder head failure.
- 3
Verify Encoder Cable Shield and Connections
Inspect encoder cable at both encoder head and CC/PLC X41x connectors. Check shield connection at both ends - shield must connect 360° at CC end. Measure encoder supply voltage at connector (should be 5V ±0.25V).
EnDat cables are particularly sensitive to improper shield termination. Use the screw-down shield clamps, not the cable gland alone.
- 4
Review MP6410 Encoder Parameters
Check MP6410.x for the affected axis (where x = axis number). Verify encoder type matches physical encoder. For EnDat encoders, ensure MP6410 is set to type 5 or 6.
Changing encoder parameters requires a control restart and may require axis reference point search.
Call a technician if:
- ·Hardware encoder/amplifier replacement needed
- ·Complex kinematic reconfiguration required
- ·PLC program modifications beyond parameter changes
Prevention
- Regular backup of machine parameters
- Periodic encoder signal quality checks
- Systematic documentation of kinematic changes
- Routine PLC program validation
Common Mistakes
- Forgetting to restart after parameter changes
- Mixing up axis numbering in parameters
- Ignoring encoder signal quality degradation
- Modifying kinematics without understanding dependencies
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Always verify with your machine manual or a certified technician before performing service procedures.