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fanuc-alarm-severity-guide.md

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title FANUC Alarm Severity Levels — Handling and Color Codes
domain fanuc
subdomain troubleshooting
tags
alarm
severity
warn
pause
stop
servo
abort
system
troubleshooting
status published
source internal-training
confidence 0.95
created 2026-07-14

Problem

FANUC controllers display alarms with different severity levels, but engineers don't always understand the implications of each level — which ones stop the robot, which cut servo power, and which require immediate action vs. can be deferred.

Solution

Alarm Severity Table

Severity Program Robot Motion Servo Power Scope
NONE No stop No stop Not cut ...
WARN No stop No stop Not cut ...
PAUSE.L / PAUSE.G Pause Decel then stop Not cut Local / Global
STOP.L / STOP.G Pause Decel then stop Not cut Local / Global
SERVO Force end Instant stop Cut Global
ABORT.L / ABORT.G Force end Decel then stop Not cut Local / Global
SERVO2 / SYSTEM Force end Instant stop Cut Global

Severity Descriptions

  • WARN: Warning for minor/non-critical issues. LED does NOT light up.
  • PAUSE: Pauses program execution, robot stops after completing current motion. Servo stays on.
  • STOP: Pauses program execution, robot decelerates to stop. Servo stays on.
  • SERVO: Interrupts or force-ends program, robot stops INSTANTLY, servo power CUT. Most dangerous motion stop.
  • ABORT: Force-ends program, robot decelerates to stop. Servo stays on.
  • SYSTEM: System-level critical issue. ALL operations stop.

Alarm Color Codes

Color Severities Meaning
White NONE, WARN Informational, no action needed
Yellow PAUSE.L/G, STOP.L/G Caution, check before resuming
Red SERVO, SERVO2, ABORT.L/G, SYSTEM Critical, investigate immediately
Blue Reset, SYST-026 System normal startup

Common Alarm Codes

Servo alarms:

  • SRVO-001: Operator panel emergency stop
  • SRVO-002: Teach pendant emergency stop
  • SRVO-007: External emergency stop
  • SRVO-012: Power failure recovery
  • SRVO-048: DCS SSO external emergency stop
  • SRVO-062: DSP not running

Program alarms:

  • INTP-127: Power failure detected
  • INTP-224: Cannot branch
  • MEMO-027: Specified line not found

System alarms:

  • SYST-026: System normal startup
  • SYST-039: T2 operation mode selected
  • SYST-212: DCS parameters need application
  • SYST-218: DCS function not available for this model

Alarm Recovery Procedures

  1. Identify: Read alarm code and severity from TP display
  2. Investigate: Check alarm history (MENU → Status → Alarm)
  3. Resolve: Fix root cause (not just reset)
  4. Reset: Press RESET key after root cause is fixed
  5. Verify: Confirm servo power restores and robot operates normally

DCS Safety Alarms

DCS (Dual Check Safety) uses independent dual CPUs to monitor:

  • Position limits
  • Speed limits
  • Joint speed limits

DCS parameters are stored separately from regular parameters. Changing DCS requires 4-digit password (default: 1111).

Stop distance = (Motion speed × Scan time) + Coast distance at power cutoff

  • Standard scan time: 8ms
  • Safety signal latency: 2ms (DCS I/O), 4ms (PROFINET)

Verification

  1. Trigger a WARN-level alarm — verify robot continues operating
  2. Trigger a PAUSE-level alarm — verify robot decelerates gracefully
  3. Trigger a SERVO-level alarm — verify servo power is cut immediately
  4. Check alarm history after each test — verify correct logging

Notes

  • WARN alarms don't light the LED — easy to miss in production
  • SERVO alarms are the most dangerous — instant stop can damage tooling
  • Always fix root cause before pressing RESET
  • DCS alarms require special handling — DCS parameters are password-protected
  • Alarm history is cleared on power cycle — export before shutdown if needed