What needs to be done when replacing encoder UTTSH-B24RH for Yaskawa servo motor SGM7G-09AFC61

Original brand-new genuine UTTSH-B24RH (Σ7 compatible absolute エンコーダ). No manual motor code/motor constant writing required, but encoder home alignment + absolute encoder initialization must be performed.

1. Two Scenarios to Distinguish
2. Brand-new original Yaskawa UTTSH-B24RH (factory pre-programmed)

The encoder already stores the motor ID and constants for the SGM7G at the factory. The drive automatically reads motor information from the encoder after power-up. No SigmaWin+ motor code writing needed.

✅ Mandatory tasks:

Mechanical assembly: Align the triangular mark on the encoder with the rotor mark on the motor (magnetic pole home alignment — the most critical step. Misalignment triggers alarm A.840, runaway or vibration).

電源投入後: Run absolute encoder initialization (procedure to clear A.810/A.820 alarms) via SigmaWin+ or the front panel to reset multi-turn position data.

電源を入れ直します, confirm no alarms, jog test for motor rotation direction and magnetic pole status.

2. Refurbished / used UTTSH-B24RH (second-hand encoder with data from another motor)

⚠️ You must write the SGM7G-09AFC61 corresponding motor constants/motor code into the encoder via SigmaWin+. Otherwise the drive misidentifies the motor model and throws A.040 or A.840; normal operation is impossible.

2. Full Post-Replacement Checklist
3. Mechanical fitting: Align encoder triangular mark to rotor triangle, tighten screws (magnetic pole home alignment, top priority for Σ7 absolute encoders).
4. 配線検査: Encoder cable, battery (absolute multi-turn battery; low battery causes A.810).
5. 電源を入れる. The drive will attempt motor recognition. New encoders normally trigger A.810 (encoder backup alarm) — this is expected.
6. Execute absolute encoder initialization (clear A.810).
7. Power off then restart, confirm alarm clears. Jog test; check rotation direction, abnormal noise and vibration.
8. If A.840 appears: Magnetic pole home alignment failed. Readjust encoder mechanical angle; this is not a code-writing issue.
9. Common Alarm Descriptions

A.810: Absolute encoder uninitialized (normal for new encoders, cleared after initialization).

A.840: Magnetic pole detection fault. 90% caused by misaligned mechanical marks on encoder, not parameter/code problems.

あ.040: Motor parameter mismatch → used encoder containing foreign motor constants. SigmaWin is required to write the correct motor data.

4. 補足事項

The SGM7G-09AFC61 is a Σ7 0.9 kW absolute motor. The UTTSH-B24RH is its matched 24-bit multi-turn absolute encoder. Σ7 motor constants are stored inside the encoder itself, not in the drive. This differs from Σ5. After encoder replacement, the drive reads motor information from the encoder.

要するに: For brand-new original UTTSH-B24RH, perform mechanical mark alignment + absolute initialization only. For second-hand/refurbished encoders, additionally write the motor code via software.

Σ7 (SGM7G) Absolute Encoder Initialization with SigmaWin+ Ver7 (Clear A.810)

Prerequisite: サーボオフ, mechanical home marking completed, wiring and battery verified healthy, drive powered on, USB PC connection established and SigmaWin+ online.

Software Procedure

1. Enter online mode and successfully connect to the SGD7S drive.
2. Top menu: Setup → Absolute Encoder Reset, popup window opens.
3. Click【Continue】. The software automatically detects the current alarm (usually A.810).
4. Click【Execute setting】.
5. Confirm again and click【Continue】to run multi-turn data clear / encoder initialization.
6. Once finished, power off the drive, wait for panel lights to fully extinguish, then power back on.
7. Check alarms after reboot. A.810 disappearing means success. If A.810 persists, inspect encoder battery / 配線. A.840 indicates misaligned magnetic pole marks.

Drive Front Panel Operation (Fn008, PC-free alternative)

1. サーボオフ. Press MODE to switch to auxiliary function Fn.
2. Use up/down keys to locate Fn008 (Absolute Encoder Reset).
3. Press and hold DATA/SHIFT for >1 second to enter.
4. Press UP until `PCCLS` is displayed.
5. Press SET to confirm and execute reset.
6. Hold DATA/SHIFT to exit, power cycle the drive.

⚠️ Extra Steps for Used Encoders (Second-hand UTTSH-B24RH)

If the encoder is not brand-new original and A.040 motor parameter mismatch appears after power-up:

1. Go online in SigmaWin+, open【Motor Parameter Management】.
2. Export and back up old motor parameter file first if using the old encoder.
3. Select the motor constant package corresponding to SGM7G-09AFC61 and download/write it to the encoder.
4. Finish writing, power cycle, then perform the A.810 absolute initialization above.

Post-Power-on Validation Checklist

✅ No A.810 / A.840 after power-up

✅ Servo ON, jog test: normal rotation, no vibration or abnormal noise

✅ SigmaWin monitor shows motor identified as SGM7G-09AFC61

✅ Absolute position reads correctly

Common Pitfall Warnings

1. Misaligned triangular magnetic pole marks = guaranteed A.840. Software initialization cannot fix this; only mechanical realignment works.
2. If the absolute battery is dead, A.810 reappears after reset and reboot. Replace the battery pack directly.
3. Initialization clears only multi-turn position data; it cannot repair magnetic pole home position.

トラブルシューティング: Motor Fails to Run After UTTSH-B24RH Encoder Replacement on SGM7G-09AFC61

Top root causes for Σ7: Magnetic pole home misalignment (A.840) Uninitialized absolute encoder (A.810) Encoder hardware / wiring Motor parameter mismatch (あ.040)

ステップ 1: Read Drive Alarm Code (Most Important)

Record the alarm code shown on the panel to determine troubleshooting direction.

1. A.840 Magnetic Pole Detection Fault (Most Frequent)

Symptoms: Alarm triggers when servo turns ON; motor vibrates, makes abnormal noise, runs away or cannot jog.

原因: Triangular marks on encoder and rotor are not aligned. Σ7 absolute encoder magnetic pole home is defined by mechanical marks and cannot be corrected by software.

救済策:

電源を切る, fully discharge. Loosen encoder fixing screws.

Rotate encoder body to align encoder triangle mark with motor rotor triangle mark.

Tighten screws, power on again and run Fn008 absolute reset.

ヒント: Marks must align precisely; deviation of a few degrees causes A.840. Do not repeatedly power on for testing — risk encoder magnetic ring damage.

2. A.810 Absolute Encoder Backup Alarm

Symptoms: Alarm on power-up; servo cannot turn ON.

原因: Multi-turn position lost after new encoder / encoder swap; or dead battery / loose battery wiring.

救済策:

Confirm absolute battery pack wiring intact and battery voltage normal (≥3.6V).

Run Fn008 (PCCLS) absolute reset → power cycle.

A.810 still present after reset and reboot: replace battery pack directly.

3. あ.040 Motor Parameter Mismatch

Symptoms: Motor recognition fails on power-up; servo cannot start.

原因: Second-hand encoder stores constants not belonging to SGM7G-09AFC61.

救済策: Connect SigmaWin+ online, write SGM7G-09AFC61 motor parameters to encoder, power cycle then run absolute reset.

4. No alarm, but motor does not rotate when servo ON

Focus inspection points:

Servo enable DI signal properly received by drive. Check【Servo Command Status】in SigmaWin monitor.

制御モード: 位置 / speed mode command present; pulse or speed setpoint not zero.

Torque limit parameter too low (Pn405 torque limit set to zero).

Emergency stop terminal or hardware limit circuit open.

5. A.820 Encoder Communication Fault

Symptoms: Random alarm after power-on, communication dropout.

原因: Loose encoder cable, bent pins, poor shielding or defective encoder.

救済策: Re-seat encoder connector, inspect pins, test with replacement encoder cable.

ステップ 2: General Troubleshooting Flow for No-Alarm No-Run Condition

1. 配線を確認してください: Encoder connector, power connector, 24V control supply and absolute battery wiring are all secure.
2. SigmaWin+ online monitoring:

【Motor Model Recognition】: Confirmed as SGM7G-09AFC61. Question mark = encoder parameter / communication fault.

【Servo Status】: Check servo ON signal, command input and alarm state.

3. First perform jog test in speed mode (set Pn000 to speed control). Avoid position mode directly to isolate motor basic functionality.
4. 振動 / abnormal noise during jog: Almost always magnetic pole misalignment; re-align marks.

ステップ 3: Recommended Verification Sequence (Strictly follow this order)

1. Power off and discharge → check encoder triangular mark alignment.
2. Inspect encoder cable and battery voltage.
3. Power on and read alarm code.
4. If A.810: Run Fn008 reset, power cycle.
5. If A.040: Write motor parameters via SigmaWin, power cycle.
6. If A.840: Re-do mechanical encoder alignment.
7. No alarm but no movement: Check DI enable, control commands, torque limits.
8. Final step: Cross-test with spare encoder to rule out encoder hardware failure.

Critical Warnings

❌ Do not repeatedly enable servo for testing under A.840. Multiple power cycles may damage encoder magnetic rings.

❌ Absolute reset (Fn008) cannot repair magnetic pole home position — this is a frequent mistake.

❌ Σ7 motor parameters reside in encoder, not drive. Second-hand encoder replacement requires motor parameter writing.