Cooling fan
Common VFD, drive, UPS, and cabinet overheating failure point.
Okuma CNC Alarm 1600 — Communication Error: What It Means
Okuma Alarm 1600 indicates a communication error between the CNC control unit and a servo or spindle drive — the OSP (Okuma Software Platform) control is not receiving valid communication from one of the OPUS/DRIVE axis or spindle amplifiers on the Okuma CC-Link or proprietary drive communication bus. Each Okuma drive module communicates position and status data to the OSP over a serial link; when that link is interrupted or returns corrupted data, Alarm 1600 is stored and the machine stops. The alarm will typically specify which axis or drive station number is affected.
Common Causes
- Loose or damaged communication cable between control and drives — The flat or shielded cable connecting the NC control to the drive rack can loosen from vibration or coolant exposure.
- Failed drive module — A servo amplifier or spindle drive that stops responding to the communication bus triggers 1600 for its station.
- Power supply failure in the drive section — Loss of the 24VDC control power supply to the drive modules causes communication to drop.
- ENC/DRV board fault in the NC unit — The Okuma NC unit’s communication interface board (ENC or DRV board) fails, causing all drives to report communication loss.
Step-by-Step Fix
- Identify the station number — Read the full alarm message on the Okuma OSP display. Alarm 1600 will include a station number (e.g., 1600-01) that identifies which axis or spindle drive has the communication problem.
- Inspect the communication cable — With power off (LOTO applied), trace the communication cable from the NC control cabinet to the drive rack. Check both connectors for secure seating, bent pins, and coolant damage.
- Check 24VDC control power — Measure 24VDC at the drive rack’s control power input terminals. Loss of 24V shuts down all drive communication. Trace back to the 24VDC power supply if voltage is absent.
- Reseat the drive module — For the identified station drive, loosen and reseat the drive module firmly in its rack slot. Drive modules use a card-edge connector that can develop contact issues over time.
- Check for drive-level fault LEDs — Okuma drive modules typically have status LEDs on the front panel. A red or blinking LED on the identified station indicates a drive-level fault that is causing communication loss — resolve the drive fault first.
- Power cycle the machine — After any physical corrections, perform a full machine power cycle (control off, drives off, 30-second wait, drives on, control on). Observe the startup sequence for any remaining faults.
Parts Often Needed
| Part | Notes |
|---|---|
| Drive communication cable | Okuma model-specific; flat ribbon or shielded serial cable |
| 24VDC control power supply | If 24V is absent; match voltage and current rating |
| Drive module (servo amplifier) | If station-specific drive fault persists after reseating |
Need Replacement Parts?
Before ordering, match the machine-control part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Pro
Okuma OSP control and drive communication diagnostics require Okuma service manuals and specialized knowledge of the OPUS drive architecture. If power and cabling check out but 1600 persists, contact Okuma America service or an Okuma-authorized technical center for drive module and control board diagnostics.