Okuma OSP codes
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Okuma OSP Controller

Servo/Axis · Intermediate

Alarm 2686

Okuma OSP Alarm B 2686 - MCS Rotary encoder 4 error

The MCS detected illegal data coming from rotary encoder 4 (HEIDENHAIN) on the axis shown in the object field. The encoder is communicating but the position data it sends is invalid, so the axis cannot be trusted for feedback.

Okuma OSPServo/AxisIntermediate

2686

Okuma OSP Alarm B 2686 - MCS Rotary encoder 4 error

MCS Rotary encoder 4 error

The MCS detected illegal data coming from rotary encoder 4 (HEIDENHAIN) on the axis shown in the object field. The encoder is communicating but the position data it sends is invalid, so the axis cannot be trusted for feedback.

Common Causes

  • Defective HEIDENHAIN rotary encoder 4 sending corrupt data
  • Damaged encoder cable or poor shielding letting noise corrupt the data
  • Loose connector at the encoder or MCS end

Troubleshooting Steps

  1. 1Identify the axis from the object field, then lock out power before handling encoder connectors.
  2. 2Reseat the rotary encoder 4 (HEIDENHAIN) connector and inspect the cable run for crushing, coolant soak, or chafing against the casting.
  3. 3Check that the encoder cable shield is properly grounded at the drive end, since noise on a HEIDENHAIN signal line produces exactly this kind of illegal data error.
  4. 4Power up and command slow jog moves on that axis while watching for the alarm to return.
  5. 5If the illegal data error persists with verified cabling and grounding, the corrective action is to change rotary encoder 4 (HEIDENHAIN) per the manual.

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