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Heidenhain Controller
Servo/Axis · Intermediate · 30-120 minutes
HEIDENHAIN 230-0445 - Velocity error (axis) too great
This alarm fundamentally indicates the position control loop cannot maintain adequate velocity tracking, meaning the axis is not moving as fast as commanded. This stems from either improper feedback (encoder issues), inadequate drive response (tuning/mechanical), or incorrect parameter scaling that causes the control to misinterpret actual velocity. The control's position loop expects velocity error to remain within MP1210 limits during motion.
230-0445
HEIDENHAIN 230-0445 - Velocity error (axis) too great
Velocity error (axis) too great
The velocity difference between the position encoder and speed encoder readings is too large. This indicates a potential coupling or encoder problem.
Root Cause Summary
This alarm fundamentally indicates the position control loop cannot maintain adequate velocity tracking, meaning the axis is not moving as fast as commanded. This stems from either improper feedback (encoder issues), inadequate drive response (tuning/mechanical), or incorrect parameter scaling that causes the control to misinterpret actual velocity. The control's position loop expects velocity error to remain within MP1210 limits during motion.
Safety
- Refer to Heidenhain service manual
- Ensure qualified technician performs repairs
Causes and Fixes
- 1
Access Encoder Diagnostics
Press MOD button, navigate to Test -> Encoder Test. Select the affected axis and observe the position value while manually jogging at slow speed. Look for counting errors, reversals, or non-smooth increments.
Enable the oscilloscope function if available (TNC 640/620) to view actual encoder signals A/B/R in real-time. Clean square waves with proper amplitude (typically 1Vpp or 11µApp for 1Vpp) indicate healthy signals.
- 2
Inspect Encoder Cable and Connections
Power down machine, check encoder cable from motor to TNC for damage, sharp bends, or proximity to power cables. Verify D-sub connector pins at control side (X111-X116 typical) and motor junction box are tight and corrosion-free.
Ensure proper lockout/tagout procedures before opening control cabinet. Do not disconnect encoder while control is powered.
- 3
Verify Encoder Power Supply
Measure encoder supply voltage at motor junction box: should be 5VDC ±5% for TTL encoders or 8-12VDC for 1Vpp types. Check MP1700 for configured encoder voltage and verify power supply module output.
Low encoder supply voltage (below 4.75V for TTL) causes signal amplitude degradation. Check total current draw if multiple encoders share one supply; may need separate supply module.
- 4
Test with Spare Cable
If available, temporarily replace encoder cable with known-good spare of identical type and length. Re-test axis movement. If alarm clears, original cable is faulty despite possibly passing visual inspection.
Encoder cable failures often occur at flex points near cable carriers. Flex-rated encoder cables are essential for moving machine components.
Call a technician if:
- ·Encoder replacement required
- ·Drive amplifier failure confirmed
- ·Mechanical component replacement needed
Prevention
- Regular encoder cleaning and inspection
- Maintain proper lubrication schedules
- Monitor servo parameters during routine maintenance
- Keep encoder cables properly routed and secured
Common Mistakes
- Adjusting servo parameters without understanding their interaction
- Ignoring mechanical binding symptoms
- Not checking both position and speed encoder signals
- Cleaning encoders with inappropriate solvents
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Always verify with your machine manual or a certified technician before performing service procedures.