Yaskawa Σ-7 (Sigma-7) SERVOPACK alarm A.d00: Position Deviation Overflow
Alarm A.d00 on a Yaskawa Σ-7 SERVOPACK is Position Deviation Overflow: the position deviation (following error) exceeded the setting of Pn520 (Position Deviation Overflow Alarm Level). It is the Σ-7 equivalent of a following-error fault.
Diagnose this with AI
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When it happens
- During acceleration, when the position reference demands more than the motor can follow
- On the first move after servo ON if U, V, W wiring is wrong
- Any time the axis is blocked or a torque limit is active
Likely causes and checks
1Servomotor U, V, W wiring incorrect or loose
- Points to it
- Fault on the first move after a rewire; motor jerks or runs away briefly.
- Check
- Check the wiring of the Servomotor Main Circuit Cables and the encoder for faulty contacts.
2Position reference speed too fast
- Points to it
- Fault only at the highest speeds.
- Check
- Reduce the reference speed and try again; reconsider the electronic gear ratio.
3Position reference acceleration too high
- Points to it
- Fault during the acceleration ramp, not at constant speed.
- Check
- Reduce the reference acceleration, or smooth it with the position reference filter (ACCFIL) in the MECHATROLINK command.
4Pn520 set too low for the operating conditions
- Points to it
- Motion is healthy but deviation at top speed is close to Pn520.
- Check
- Compare Pn520 with Yaskawa’s formula: maximum speed/60 × encoder resolution/(Pn102/10) × Pn210/Pn20E × (1.2 to 2).
5SERVOPACK failure
- Points to it
- Wiring, reference and settings all check good.
- Check
- Cycle power; if the alarm persists, Yaskawa says the SERVOPACK may be faulty.
Telling it apart
- A.900 is the warning that the deviation passed Pn520 × Pn51E/100; A.d00 is the alarm at the full Pn520 level.
- A.d01 is raised when servo is turned ON with deviation already above Pn526 (the axis was moved while servo was OFF); A.d02 relates to the speed limit applied at servo ON.
- Raising Pn520 hides the symptom; if deviation grows with acceleration, fix the reference or the mechanics first.
Relevant parameters
| Parameter | Name | Why it matters |
|---|---|---|
| Pn520 | Position Deviation Overflow Alarm Level | Range 1 to 1,073,741,823 reference units; default 5,242,880. |
| Pn51E | Position Deviation Overflow Warning Level | 10 to 100 %, default 100 %; A.900 occurs at Pn520 × Pn51E/100. |
| Pn102 | Position Loop Gain | Used in the Pn520 sizing formula (Pn141 instead when model following control is enabled). |
| Pn526 | Position Deviation Overflow Alarm Level at Servo ON | Threshold for A.d01. |
Evidence to collect
- Alarm history and whether A.900 preceded A.d00
- Speed and position deviation trace for the failing move
- Pn102, Pn210/Pn20E and Pn520 values
- Reference speed and acceleration from the controller
- Recent wiring or motor changes
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