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Okuma OSP Controller
Communication · Intermediate
Okuma OSP Alarm A 1176 - Mistake in data from NC to MCS
The NC and the inverter (MCS) unit exchange commands and responses at fixed intervals over the servo link, and the control detected that data sent from the NC to the inverter used a wrong protocol or arrived with abnormal timing. The object shown is the affected axis name, or none if the spindle is involved. This points to a control-side communication fault rather than a machine mechanical problem.
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Okuma OSP Alarm A 1176 - Mistake in data from NC to MCS
Mistake in data from NC to MCS
The NC and the inverter (MCS) unit exchange commands and responses at fixed intervals over the servo link, and the control detected that data sent from the NC to the inverter used a wrong protocol or arrived with abnormal timing. The object shown is the affected axis name, or none if the spindle is involved. This points to a control-side communication fault rather than a machine mechanical problem.
Common Causes
- Defective inverter unit control board
- NC software fault or corruption
- Inverter unit control board firmware not compatible with the installed NC software version
- Faulty FCP board
Troubleshooting Steps
- 1Read the code number shown with the alarm: code 1 = A-buffer software synchronization error — timing of the NC-to-inverter transfer was off; code 2 = A-buffer format code error — data content did not follow the specified protocol; code 3 = B-buffer software synchronization error — timing fault on the B-buffer transfer; code 4 = B-buffer format code error — protocol violation in the B-buffer data; code 5 = B-buffer block number error — data blocks arrived out of sequence or were lost
- 2Note the code and object on the alarm screen. Codes 1 and 3 are A-buffer/B-buffer software synchronization errors (timing); codes 2 and 4 are format code errors (wrong protocol content); code 5 is a B-buffer block number error (lost or out-of-sequence data).
- 3Note whether the object is a specific axis or blank (spindle) — this identifies which inverter unit is involved in the faulty exchange.
- 4Power down, lock out, and let the drive bus discharge. Reseat the servo link connections between the NC/FCP side and the suspect inverter unit control board, then power up and see if the alarm recurs.
- 5If the alarm appeared right after a board or software change, verify the inverter unit control board is compatible with the installed NC software version; a mismatched board must be replaced with the correct revision.
- 6If the fault persists, replace the inverter unit control board for the indicated axis; if it still persists, suspect the FCP board or NC software and contact Okuma service with the recorded code and object.
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