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Heidenhain Controller
System · Intermediate · 30-120 minutes
HEIDENHAIN 231-94E0 - 94E0 Switching EnDat 2.2 to 1 Vpp requires reinitialization
Alarm 231-94E0 occurs when the TNC control detects a mismatch between the configured encoder interface type and the actual encoder connected to the drive. This typically happens after encoder replacement or when machine parameters MP720 (encoder type) don't match the physical encoder interface.
231-94E0
HEIDENHAIN 231-94E0 - 94E0 Switching EnDat 2.2 to 1 Vpp requires reinitialization
94E0 Switching EnDat 2.2 to 1 Vpp requires reinitialization
The position encoder interface was switched between EnDat 2.2 and 1 Vpp, so the drive must be reinitialized before the axis can run again.
Root Cause Summary
Alarm 231-94E0 occurs when the TNC control detects a mismatch between the configured encoder interface type and the actual encoder connected to the drive. This typically happens after encoder replacement or when machine parameters MP720 (encoder type) don't match the physical encoder interface.
Safety
- Refer to Heidenhain service manual
- Ensure qualified technician performs repairs
Causes and Fixes
- 1
Access machine parameters
Press MOD key, select 'Machine parameters', navigate to MP720 for the affected axis using the axis selection softkey.
Always document original MP720 values before making changes
- 2
Verify encoder type setting
Check MP720 value - '1' for EnDat 2.2, '0' for 1Vpp. Compare with actual encoder specifications on nameplate or documentation.
Incorrect MP720 setting can damage encoder or drive electronics
- 3
Update MP720 parameter
Change MP720 to match installed encoder type. Enter new value and confirm with ENT key.
EnDat encoders typically have 'EnDat' marking on label, 1Vpp encoders show sine wave symbols
- 4
Perform drive reinitialization
Execute PLC function 'Initialize drives' from service menu or cycle power to TNC control completely.
Ensure machine is in safe position before drive reinitialization
Call a technician if:
- ·Hardware interface failure confirmed
- ·Multiple axes affected simultaneously
- ·Firmware update required
Prevention
- Always update MP720 when replacing encoders
- Backup parameters before encoder changes
- Verify encoder specifications before installation
- Use proper ESD procedures when handling encoder cables
Common Mistakes
- Forgetting to update MP720 after encoder replacement
- Mixing EnDat and 1Vpp parameter settings
- Not performing drive reinitialization after changes
- Assuming all encoders on machine are same type
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Always verify with your machine manual or a certified technician before performing service procedures.