Okuma OSP codes
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Okuma OSP Controller

Power Supply · Intermediate

Alarm 4155

Okuma OSP Alarm D 4155 - MCS Converter link error

The link that lets the inverter unit talk to the power unit has failed, so the NC can no longer supervise power-unit status. The object tells which axis or spindle drive group is affected; the code separates a general communication fault from a timeout where communication dropped out.

Okuma OSPPower SupplyIntermediate

4155

Okuma OSP Alarm D 4155 - MCS Converter link error

MCS Converter link error

The link that lets the inverter unit talk to the power unit has failed, so the NC can no longer supervise power-unit status. The object tells which axis or spindle drive group is affected; the code separates a general communication fault from a timeout where communication dropped out.

Common Causes

  • Converter link cable or connector loose, damaged, or poorly seated
  • Power unit fault preventing normal link response
  • Inverter unit control board failure
  • Noise or grounding problem corrupting the drive-to-drive communication path

Troubleshooting Steps

  1. 1Read the code number shown with the alarm: code X=0 = Communication error on the converter link; code X=1 = Timeout; communication was interrupted and YY will be 0; code YY = Communication status detail when X=0; always 0 for a timeout
  2. 2Note the object and whether X is 0 or 1; X=1 means the link stopped answering, so treat it as an interruption rather than random data corruption.
  3. 3Lock out incoming power and wait for the DC bus to discharge before opening the drive cabinet or touching converter-link connectors.
  4. 4Inspect and reseat the converter link cable at both ends; look for bent pins, cracked latches, oil ingress, chafing, and a shield that is not bonded cleanly.
  5. 5Check cable routing and grounding: keep the link away from motor/power leads and confirm the drive cabinet ground straps are tight.
  6. 6Verify the power unit has control power and no blown fuses or fault LEDs; a dead power unit can present as a link timeout.
  7. 7If the cable and power unit checks are clean, isolate by substitution in this order: known-good link cable, then inverter control board, then power unit.

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