FAQ# MNEN-5CJMKE Published: 06/30/2008

Question:What are some potential causes of an A.84 Alarm?
Answer:An A.84 (A84) alarm is an encoder data error alarm. This alarm is valid for both absolute and incremental encoders, and its meaning depends on the type of encoder.

Most common application issues that cause an A.84 alarm are:
- Excessive Mechanical Vibration
- Excessive Electrical Noise

If efforts to reduce the above causes do not eliminate the A.84 Alarm, Contact Yaskawa Technical Support for further assistance at 1-800-927-5292, then press 3 for Servo Products.

Detailed Information:

12 bit Absolute Encoder
This indicates that the absolute encoder data is abnormal. If this alarm appears at power on, the absolute encoder is malfunctioning and replacement may be necessary. If this alarm appears during motor operation, it could be caused by external electrical noise. In this case, check and correct wiring around the encoder (grounding of servo motor, separation of encoder and power cables, insertion of toroidal cores on cables, etc.) - to reduce noise.

Incremental Encoder
This indicates that data in the encoder is abnormal. If this alarm appears either during operation or at power on (intermittently or static), most commonly system vibration should be examined. Excessive vibration (exceeding motor specifications) (See FAQ # MTN-5XTTDJ) can cause high vibration forces at the cantilevered encoder end (G-forces generated by vibration cause an A.84 alarm if they exceed the motors rated spec). Remedies include: Decrease acceleration values, implement S-Curve acceleration, check the mounting face accuracy and alignment, check the coupling alignment. If alarm persists, permanent damage to encoder may have occurred and motor replacement may be required.

Product Information:

Product Group:Motion
Product:SGDH Sigma II
Category:Alarm; Troubleshooting

Other Information:

Link to related files:

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