What causes FANUC alarm 365?

Too many synchronous pairs defined in the parameters for this path. Spindle axis count combined with synchronous axes exceeds the per-path limit. Parameter configuration after option upgrade assigns more axes than licensed. Multi-path system with axes shared between paths exceeding the per-path maximum.

How do I fix FANUC alarm 365?

1. Check the total count of synchronous and spindle axes configured for this path. 2. Compare against the maximum axes per path specification for this Fanuc series and option. 3. Reduce the number of synchronized axes if it exceeds the limit. 4. Contact Fanuc if the configuration should be within limits — may require option upgrade.

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FANUC Controller

Program/G-code · Advanced · 2-4 hours

Alarm 365

Fanuc Alarm 365 - TOO MANY MAXIMUM SV/SP AXIS NUMBER PER PATH

Fanuc Alarm 365 indicates a catastrophic failure of the LED circuitry within the built-in pulse coder (serial encoder) of the servo motor on the specified axis. The encoder's internal LED has either failed or broken, preventing the optical detection system from reading position data. This alarm typically requires immediate pulse coder or motor replacement as the LED failure is not field-repairable.

FANUCProgram/G-codeAdvanced2-4 hours

365

Fanuc Alarm 365 - TOO MANY MAXIMUM SV/SP AXIS NUMBER PER PATH

TOO MANY MAXIMUM SV/SP AXIS NUMBER PER PATH

Root Cause Summary

Fanuc Alarm 365 indicates a catastrophic failure of the LED circuitry within the built-in pulse coder (serial encoder) of the servo motor on the specified axis. The encoder's internal LED has either failed or broken, preventing the optical detection system from reading position data. This alarm typically requires immediate pulse coder or motor replacement as the LED failure is not field-repairable.

Causes and Fixes

1
Navigate to DIAGNOSIS > SERVO > screen and check servo amplifier LED status. Record the alpha-numeric LED code displayed on the amplifier (αiSV or βiSV series). Note any accompanying alarms in the alarm history (ALARM > HISTORY).
2
Check parameter 1815 (serial pulse coder type) and parameter 1820 (pulse coder connection) to verify encoder configuration matches motor nameplate specifications. Compare encoder serial number on motor label with system configuration.
3
Power off CNC and amplifier completely. Inspect encoder cable connection at motor and amplifier. Check for bent pins, corrosion, or moisture in connectors. Verify cable shield continuity and proper grounding at both ends.
De-energize system completely before connector inspection. Follow LOTO procedures.
4
If connections are intact, pulse coder replacement is required. Order replacement motor with pulse coder or separate pulse coder assembly (if separable on your motor model). After replacement, perform encoder setup using SYSTEM > PMC > SETTING > ENCODER and execute absolute position reset using parameter 1815#1 and dog position detection sequence.
Absolute encoder position will be lost. Establish mechanical reference before motor replacement.

Service Recommendedmedium confidence

Call a technician if:

·Motor replacement required
·Servo amplifier replacement needed
·Parameter backup/restore required

Prevention

Regular encoder cable inspection
Maintain proper environmental sealing
Monitor servo alarm history for early warning signs
Keep encoder connections clean and tight

Common Mistakes

Attempting to repair built-in pulse coder LED
Using non-Fanuc encoder cables
Ignoring preceding intermittent encoder alarms
Operating with contaminated motor environment

Related Alarms

308 309 310 401 414

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