There are several possible causes of the Fanuc 366 alarm. Some of the most common causes include:
flowing through the servo amplifier or motor. It is often triggered when the motor is not compatible with the driver or if there are severe electrical issues in the power circuit. Tri Star CNC Services Alarm Report: SV0366 Alarm Name SV0366: Abnormal Current Fault Source Servo Amplifier, Servo Motor, or Feedback Cables Primary Meaning fanuc 366 alarm
| Cause | Example (Error) | Explanation | | :--- | :--- | :--- | | | #101 = #102 + [ #103 * #104 | Mismatched square brackets [ and ] . Parentheses ( ) are not allowed for math grouping (only for comments). | | 2. Illegal Character in Expression | #101 = #102 + #103*#104@ | Using invalid characters like @ , & , $ , ^ , or unescaped symbols. | | 3. Incorrect Conditional Format | IF #101 EQ #102 GOTO100 | Missing space before GOTO? More likely: using a GOTO number that is not defined, or missing a THEN for multi-line IF. Incorrect: IF [#1 EQ 2] GOTO 10 (Correct: IF [#1 EQ 2] GOTO10 - no space after GOTO) | | 4. Wrong THEN usage | IF #1=5 THEN #2=10 ELSE #2=20 | The THEN in a single-line IF cannot contain ELSE . That requires a multi-line IF … ELSE … ENDIF . | | 5. Missing operator | #101 = #102 #103 | Two variables side by side without an operator (+, -, *, /). | | 6. Invalid M/C/G code in macro | M98 P#1 Q#2 | Using Q in M98 is illegal. Some macro calls require specific formats (e.g., G65). | | 7. Unbalanced macro calls | Nested macro calls without proper M99 returns, causing parser confusion. | Indirectly results in 366 because the control expects an expression but sees junk. | | 8. Decimal point issue | #101 = 1.2.3 | Multiple decimal points in a numeric literal. | There are several possible causes of the Fanuc 366 alarm
If the alarm persists after replacing the fiber optic cable and verifying parameters, the problem is likely internal to the or CNC main board . At this point, contact FANUC field service or your machine tool builder for repair or replacement. Tri Star CNC Services Alarm Report: SV0366 Alarm