FANUC SP9037 Alarm 37: Speed Detector Setting Error and Troubleshooting

FANUC SP9037 means that the spindle amplifier detected an incorrect parameter setting for the spindle motor speed detector. The CNC typically displays SP9037 / SSPA:37 ILLEGAL SETTING VELOCITY DETECTOR, while the spindle amplifier displays alarm 37.

The CNC alarm list describes the direct cause as an incorrect setting for the number of pulses in the speed detector. FANUC's detailed αi spindle-amplifier maintenance procedure explains the related detection behavior: after an emergency-stop signal is input, the motor may fail to decelerate correctly or may accelerate; alarm 37 can also be issued if the motor has not completed deceleration and deactivated when the configured acceleration/deceleration time has elapsed.

For the surrounding alarm numbers, see the FANUC Spindle Alarm Codes SP9034–SP9092.

Safety Warning Before Troubleshooting SP9037

FANUC B-65280EN warns that an incorrect motor-sensor gear-tooth setting can cause the spindle motor to rotate above the specified speed. FANUC B-65285EN also states that alarm 37 can be associated with the motor accelerating after an emergency-stop input instead of decelerating.

Do not repeatedly test the spindle at high speed while SP9037 is active. Keep personnel away from the spindle and rotating components, isolate machine power before working on wiring or hardware, and have a qualified technician verify the parameters with the machine builder's data. Do not bypass the emergency-stop circuit or change detector values by trial and error.

What Does FANUC SP9037 Mean?

The spindle amplifier calculates motor speed from the feedback produced by the motor speed detector. To interpret that signal correctly, the control must know the installed detector type and its pulse or gear-tooth count. If the parameter data describes a different detector, the calculated speed can differ from the actual motor speed.

This explains why FANUC's short CNC alarm table and detailed amplifier manual use different wording for the same alarm:

• The CNC alarm table identifies the parameter fault: the number of speed-detector pulses is set incorrectly.

• The spindle-amplifier maintenance manual identifies the unsafe operating result used in alarm detection: the motor does not decelerate correctly after emergency stop, or deceleration is not completed within the configured time.

These are not two unrelated alarm definitions. An incorrect detector scale can make the amplifier interpret speed and deceleration incorrectly. The repair therefore begins with the detector configuration and then checks whether the acceleration/deceleration time matches the actual machine.

SP9037 is primarily a parameter and configuration alarm. It does not, by itself, prove that the spindle amplifier, motor sensor or feedback cable has failed. Hardware diagnosis becomes appropriate only when the installed detector and all applicable parameters are confirmed but the feedback remains abnormal or another detector alarm is displayed.

Common Situations That Precede SP9037

SP9037 often appears after the configuration has changed or spindle parameters have been lost, restored or initialized. Record whether the alarm began after any of the following:

• CNC memory loss or replacement of a memory device

• Spindle amplifier or control-board replacement

• Spindle motor or motor-sensor replacement

• Loading a parameter file from another machine

• Automatic spindle parameter initialization with an incorrect motor code

• Manual editing of motor sensor parameters

• Spindle software or CNC upgrade

• Mechanical work that materially changed the spindle acceleration/deceleration time

If the machine previously operated normally and SP9037 appeared immediately after parameter work, compare the current spindle data with the last approved backup before replacing hardware.

1. Confirm SP9037 and Record the Installed Configuration

Before changing parameters, confirm:

• The CNC displays SP9037 or SSPA:37.

• The spindle amplifier displays 37.

• The alarm belongs to the affected spindle when the machine has multiple spindles.

• No separate alarm identifies a motor-sensor disconnection, position-coder pulse error or serial-sensor fault.

Record the complete CNC series and model, spindle amplifier model and suffix, spindle motor model and suffix, motor sensor type, spindle software series and edition, and the existing spindle parameter values. Photograph the alarm screen and amplifier display.

Back up all CNC, PMC and spindle parameters before making any change. Keep the affected machine's backup separate from files for similar machines. A matching motor nameplate does not prove that two machines use the same spindle, detector, winding, gearbox, software or machine-builder adjustment.

2. Verify the Motor Speed-Detector Type

For the αi/βi spindle configurations covered by FANUC B-65280EN/08, parameter 4010 bits 2, 1 and 0 define the motor sensor type. The cited Series 15i equivalent is 3010 bits 2, 1 and 0.

The manual includes different selections for detectors such as the αiM sensor, αiMZ/αiBZ/αiCZ analog sensors and the αiCZ serial sensor. The correct value depends on the detector physically installed and the supported spindle software.

Do not select a sensor type only from the connector used. B-65280EN shows that the connector can vary by sensor and amplifier configuration, and some detectors require a minimum spindle software edition. Confirm the sensor name, detector specification, amplifier series and software support together.

3. Verify the Speed-Detector Pulse or Gear-Tooth Count

For the same cited αi configuration, 4011 bits 2, 1 and 0 select the number of motor-sensor teeth. FANUC lists standard coded selections such as 64, 128, 192, 256, 384 and 512 λ/rev. The correct value must match the detector built into or fitted to the motor.

For supported sensors with a count outside those coded selections, parameter 4334 specifies an arbitrary number of motor-sensor teeth. In B-65280EN/08, this parameter is used for applicable values such as 96, 640, 768 or 1024 λ/rev. When 4334 is zero, the coded selection in 4011 remains effective.

This interaction is important. A technician can read 4011 correctly but still miss an incorrect nonzero value in 4334. Conversely, setting 4011 for a standard detector while an arbitrary value is active can leave the effective configuration wrong.

Verify all of the following against the exact detector table:

1. The installed motor sensor type matches parameter 4010.

2. The detector's actual pulse or gear-tooth count matches 4011 or, when applicable, 4334.

3. The selected spindle software supports that detector and count.

4. Data for the motor sensor has not been confused with the spindle position-sensor or position-coder data.

5. The parameter belongs to the correct spindle number on a multi-spindle machine.

Do not enter a commonly used value simply because the motor belongs to the same power range. The detector can differ by motor model, suffix and spindle configuration.

4. Distinguish Motor Sensor Parameters From Spindle Sensor Parameters

SP9037 concerns the motor speed detector. FANUC parameter manuals separately define detector data for the motor sensor and for spindle-position feedback devices.

For example, the cited αi manual uses 4010/4011 or 4334 for the motor sensor, while other parameters such as 4002, 4003, 3720 or 4361 can describe spindle sensor or position-coder arrangements. The exact set depends on the detector configuration.

Do not change every detector-related parameter together. Changing spindle-position feedback data to clear a motor speed-detector alarm can introduce orientation, rigid-tapping, threading or Cs-contouring faults. First identify which detector generates motor velocity feedback on the installed machine.

5. Check Parameter 4082 Against Actual Deceleration Time

FANUC B-65285EN/04 directs technicians to compare the configured acceleration/deceleration time with the actual machine time. In the CNC families listed in that procedure, the parameter is:

• 4082 for the cited Series 16i, 18i, 21i, 0i-B/C, 30i and 0i-D groups

• 3082 for the cited Series 15i group

B-65280EN/08 gives a unit of one second, a valid range of 0 to 255 and a standard initial value of 10 for the configurations shown in that manual. The maintenance procedure says to set the actual acceleration/deceleration time plus some margin.

The initial value is not a universal final setting. A spindle with high load inertia may need more than 10 seconds to decelerate under the machine's designed control. Measure the real time under the machine builder's approved test condition and compare it with the documented machine value.

However, do not increase 4082 merely to hide abnormal deceleration. If the spindle suddenly takes longer to stop than it did before, investigate the mechanical load, braking or regenerative system, command sequence and any accompanying alarm. Parameter 4082 should represent the intended machine behavior, not mask a new fault.

6. Restore the Correct Spindle Parameters From a Backup

When a known-good machine-specific backup exists, compare it with the current data and restore only the confirmed incorrect parameters according to the applicable CNC and spindle procedure.

Before restoring data, verify that the backup matches:

• The exact machine and spindle number

• The complete spindle motor model and suffix

• The installed motor speed detector

• The spindle amplifier series and suffix

• The spindle software series and edition

• Any machine-builder spindle, orientation and gearbox adjustments

After restoration, use the prescribed power-off/on sequence and retest at low speed without cutting load. Confirm that actual speed follows command correctly and that normal deceleration occurs before any higher-speed test.

7. Use Motor-Code Initialization Only When the Configuration Is Certain

FANUC B-65280EN provides an automatic spindle parameter initialization function for supported systems. In the cited manual, 4133 contains the spindle motor model code for the 16i/30i groups, with 3133 used for the Series 15i group. The initialization function is controlled through the applicable system parameter, such as 4019#7 on the cited 16i/30i families.

Automatic initialization is useful when the existing motor-specific data is corrupt and the exact FANUC motor code is known. It is not always the safest first step. FANUC expressly warns that initialization also resets previously adjusted settings, including sensor settings and orientation stop positions.

Before initialization:

1. Make a complete backup of the current spindle parameters.

2. Confirm the full motor model, suffix, detector and winding configuration.

3. Obtain the correct motor code and parameter table for the applicable B-65280EN edition.

4. Record machine-builder adjustments that must be restored after initialization.

5. Confirm whether the installed motor has a standard model code; some motors require initial generic data followed by manual entry from the motor-specific table.

After initialization, do not assume that the machine is ready for production. Restore and verify the required detector, orientation, gear-ratio and machine-specific adjustments, then complete the builder's spindle commissioning checks.

8. Perform a Controlled Retest

Once the confirmed detector or timing data has been corrected:

1. Keep the spindle unloaded and begin at low speed.

2. Compare commanded speed with actual speed.

3. Confirm that the indicated direction and speed are plausible.

4. Verify stable acceleration and deceleration.

5. Test normal stop behavior before carrying out any emergency-stop verification required by the machine builder.

6. Monitor the amplifier display and CNC alarm history.

7. Verify orientation, rigid tapping, spindle synchronization or Cs control only if those functions use data affected by the restoration or initialization.

Emergency-stop testing must follow the machine builder's safety procedure. Do not use an uncontrolled high-speed emergency stop as a first test. If the motor accelerates unexpectedly, isolate the machine and recheck the detector type, pulse count, direction data and exact parameter set before further operation.

What Not to Do for SP9037

• Do not repeatedly run the spindle at high speed to see whether the alarm clears.

• Do not guess the sensor count from the motor power rating or connector alone.

• Do not confuse motor speed-detector parameters with spindle position-coder parameters.

• Do not increase parameter 4082 before confirming that the deceleration time is normal for the machine.

• Do not initialize all spindle parameters without a complete backup and exact motor code.

• Do not load spindle parameters from another machine merely because its motor model looks similar.

• Do not bypass the emergency-stop circuit, detector alarms or safety interlocks.

• Do not replace the spindle amplifier as the first response to alarm 37 without parameter or feedback evidence.

Difference Between SP9037, SP9047 and SP9073

These alarms all involve spindle feedback, but they identify different conditions:

Do not replace the motor sensor simply because SP9037 contains the word “detector.” SP9073 directly identifies signal disconnection, while SP9047 identifies an abnormal position-coder pulse count. SP9037 first directs attention to the configured motor speed-detector data.

FANUC SP9037 Diagnostic Table

Recommended Troubleshooting Order

1. Confirm SP9037 on the CNC and alarm 37 on the spindle amplifier.

2. Stop high-speed testing and record the complete CNC, amplifier, motor, detector and spindle software information.

3. Back up all current CNC, PMC and spindle parameters.

4. Determine whether the alarm followed parameter loss, restoration, initialization, amplifier replacement, motor replacement or sensor work.

5. Verify the installed motor speed-detector type against parameter 4010 or the corresponding parameter for the CNC series.

6. Verify the detector pulse/gear-tooth count against 4011 and, when applicable, 4334.

7. Confirm that motor-sensor data has not been confused with spindle position-sensor data.

8. Compare the actual acceleration/deceleration time with parameter 4082, or 3082 for the cited Series 15i configuration.

9. Restore confirmed machine-specific data from the approved backup, or use documented motor-code initialization only when the exact configuration is known.

10. Retest at low speed, confirm plausible actual speed and normal deceleration, then complete the machine builder's commissioning and safety checks.

Technical References

• FANUC AC Servo Motor αis/αi Series, AC Spindle Motor αi Series, Servo Amplifier αi Series Maintenance Manual, B-65285EN/04, Alarm Code 37

• FANUC AC Spindle Motor αi/βi Series Parameter Manual, B-65280EN/08, automatic spindle parameter initialization, detector parameters and parameter 4082

• FANUC Series 30i/31i/32i and 0i spindle alarm lists, SP9037 / SSPA:37 ILLEGAL SETTING VELOCITY DETECTOR

Always use the manual edition that applies to the exact CNC, spindle amplifier, spindle motor, detector, spindle software and machine. Parameter numbers, detector selections and initialization procedures can differ between FANUC generations.

Need Help With FANUC SP9037 Alarm?

REACO CNC provides independent FANUC spindle alarm analysis, parameter checking, spindle amplifier repair and replacement support. Send us the CNC alarm screen, spindle amplifier display, complete CNC model, full amplifier and motor part numbers with suffixes, motor sensor information, spindle software series, current parameter backup and details of any recent replacement or parameter work.

Visit the FANUC Technical Support Center for more FANUC alarm guides, browse FANUC servo, spindle and power drives, or contact REACO CNC for assistance.

Reference Source: Beijing FANUC. This article is based on FANUC technical documentation. The correct parameter, initialization and verification procedure depends on the exact CNC, spindle amplifier, motor, detector, software and machine-builder configuration.