FANUC codes
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FANUC Controller

System · Advanced · 1-2 hours

Alarm 970

Fanuc Alarm 970 - NMI OCCURRED IN PMC LSI

Alarm 970 indicates a Non-Maskable Interrupt (NMI) has occurred within the PMC (Programmable Machine Control) LSI chip on the main PCB or PMC module. This is a critical hardware fault typically caused by PMC LSI failure, memory corruption in the PMC section, or electrical noise/voltage irregularities affecting the PMC circuitry.

FANUCSystemAdvanced1-2 hours

970

Fanuc Alarm 970 - NMI OCCURRED IN PMC LSI

NCK Error

Fanuc alarm 970: NCK Error. This alarm indicates a fault condition detected by the Fanuc control. Refer to the alarm number and name to identify the specific system or function involved.

Root Cause Summary

Alarm 970 indicates a Non-Maskable Interrupt (NMI) has occurred within the PMC (Programmable Machine Control) LSI chip on the main PCB or PMC module. This is a critical hardware fault typically caused by PMC LSI failure, memory corruption in the PMC section, or electrical noise/voltage irregularities affecting the PMC circuitry.

Safety

  • System operation compromised
  • ⚠️ CRITICAL: System operation is compromised - verify all functions before resuming production
  • Electrical Hazard: Power down and disconnect the CNC machine from the main power supply before performing any hardware inspections or repairs. Lockout/Tagout procedures should be followed.
  • Mechanical Hazard: Be aware of potential mechanical hazards if the error causes unexpected machine movements. Keep clear of moving parts.
  • Data Loss: Back up all critical data (CNC programs, parameters, offsets) before attempting any software reloads or system resets.
  • Component Damage: Improper handling of electronic components can cause damage. Use proper ESD precautions when handling circuit boards or other sensitive components.
  • Always follow safety protocols when handling electrical components.

Causes and Fixes

  1. 1

    Power OFF the machine completely. Wait 60 seconds, then power ON and observe if alarm recurs immediately or after operation begins. Document whether alarm is persistent or intermittent.

  2. 2

    Access SYSTEM > PMC > TITLE screen to verify PMC ladder program loads successfully. Check for corruption indicators or failure to display PMC information.

  3. 3

    If on modular control (0i-F, 30i/31i/32i), inspect PMC module and reseat all connectors on the PMC board. Check for visible damage, burn marks, or capacitor bulging on PMC PCB.

    Use proper ESD protection when handling circuit boards

  4. 4

    Replace the main control PCB or PMC module. Contact Fanuc service for exact board identification based on control series. Reload PMC ladder and system parameters after replacement.

    Backup all PMC ladder programs and CNC parameters before board replacement

Service Recommendedmedium confidence

Call a technician if:

  • ·PMC module replacement required
  • ·Multiple I/O modules failing
  • ·Persistent alarm after power supply verification

Prevention

  • Regular PMC backup to memory card
  • Monthly voltage monitoring checks
  • Annual I/O connection inspection
  • Maintain proper cabinet ventilation

Common Mistakes

  • Ignoring intermittent voltage drops
  • Not backing up PMC program before troubleshooting
  • Disconnecting I/O while powered
  • Assuming software issue when hardware has failed

Related Alarms

971972990991

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Always verify with your machine manual or a certified technician before performing service procedures.