FANUC SP9032 Alarm 32: Serial Communication LSI RAM Fault

FANUC SP9032 means that the spindle amplifier detected an abnormality in the memory used by its serial communication LSI. The CNC displays SP9032 / SSPA:32 SIC-LSI RAM FAULT, while the spindle amplifier displays 32.

FANUC states that this memory check is performed when power is turned on. The official repair direction is to replace the spindle amplifier control printed circuit board or the complete spindle amplifier, depending on the applicable amplifier design and service procedure.

For the surrounding spindle alarm numbers, see the FANUC Serial Spindle Alarm Codes SP9001–SP9033.

What Does FANUC SP9032 Mean?

FANUC Servo Amplifier αi Series Maintenance Manual B-65285EN/04 describes alarm code 32 as an abnormality in the LSI memory for serial communication. The memory is checked at power-on. If the test result is abnormal, the spindle amplifier cannot rely on that internal communication-control circuit for normal operation.

The Series 0i-D/0i Mate-D Maintenance Manual B-64305EN/03 uses the CNC message SIC-LSI RAM FAULT and identifies the faulty area as a spindle amplifier control-circuit component. Its stated remedy is replacement of the spindle amplifier control printed circuit board.

This wording is important. SP9032 concerns memory associated with the serial-transfer LSI inside the spindle amplifier. It is not the same as CNC program memory, machine SRAM, PMC memory, spindle parameters or an external position-coder signal.

The alarm also does not mean that ordinary serial data was corrupted somewhere in the CNC-to-amplifier cable. That condition belongs to alarm 24. Alarm 32 identifies an internal RAM self-check failure and therefore has a hardware-replacement procedure rather than a cable-troubleshooting procedure.

Why SP9032 Usually Appears at Power-On

FANUC explicitly states that the alarm 32 memory check is made when power is turned on. On affected machines, SP9032 may therefore appear during CNC and amplifier startup, before a spindle rotation command or machining cycle begins.

Because the check is internal, the alarm does not require the spindle motor to rotate and is not triggered by cutting load. Changing the commanded speed, reducing the depth of cut or disconnecting the position coder will not correct the abnormal RAM test.

An operator may report that the machine ran normally before shutdown and displayed SP9032 at the next startup. That timing is consistent with the power-on check, but it does not identify whether the repair should be a control-board replacement or complete amplifier replacement. The exact amplifier model, construction and applicable maintenance manual determine the approved hardware procedure.

Repeated power cycling is not the official repair. A temporary disappearance after restarting does not prove that the hardware is healthy. Record the alarm and have the spindle amplifier evaluated according to the applicable machine and FANUC service procedure.

1. Confirm SP9032 and Amplifier Alarm 32

Before removing hardware, confirm the exact displays:

• The CNC alarm screen shows SP9032 or SSPA:32 SIC-LSI RAM FAULT.

• The spindle amplifier status display shows 32.

• The alarm is assigned to the spindle amplifier and not to a CNC, servo, PMC or separate communication device.

• Any simultaneous power-supply, servo or spindle alarms are recorded separately.

Photograph the CNC alarm screen and amplifier display before switching off the machine. Also record:

• The complete CNC series and model

• The exact spindle amplifier or SPM model, including every suffix

• The spindle number when the machine has multiple spindles

• The spindle software series and edition when available

• Whether a control board, amplifier or CNC component was recently replaced

• Whether SP9032 appears at every startup or occurred only once

These details do not change FANUC's definition of alarm 32. They are required to identify the correct manual, compatible control board or complete replacement amplifier.

2. Do Not Treat SP9032 as an External Communication-Cable Fault

The terms serial communication and serial transfer can make alarm 32 look similar to alarm 24, but the two alarms point to different diagnostic levels.

For alarm 24, FANUC describes an error in the serial communication data transferred between the CNC and spindle amplifier. Its troubleshooting can include communication-cable length and connection, cable routing near motor power leads, a damaged electrical or optical link, the spindle amplifier and the CNC serial-spindle board or module.

For alarm 32, FANUC describes the LSI memory itself as abnormal and instructs the technician to replace amplifier hardware. The alarm 32 procedure does not direct the technician to replace the CNC-to-amplifier communication cable, separate it from the motor power cable or replace the CNC serial-spindle module.

Do not import the SP9024 procedure into SP9032 merely because both alarm descriptions contain the word “serial.” Confirm the amplifier indication. If the amplifier shows 24, follow the serial-transfer-error procedure. If it shows 32, follow the internal LSI RAM fault procedure.

3. Do Not Change Parameters or Replace Unrelated Parts

FANUC's official alarm 32 procedure does not call for spindle-parameter initialization, ladder modification, motor phase changes, sensor adjustment, feedback-cable replacement, load reduction or power-supply replacement.

SP9032 should not be used as evidence that the CNC has lost its programs or machine data. Reloading an SRAM backup does not repair memory in the spindle amplifier's serial communication circuit. Likewise, replacing the spindle motor or position coder will not address the hardware area identified by FANUC.

Avoid making several unrelated changes before confirming the alarm. Unnecessary parameter or wiring changes can create additional faults and make the original machine configuration harder to recover. Preserve the existing CNC, PMC and spindle data before service work, but do not present a data restore as the remedy for alarm 32.

4. Choose Between Control PCB and Complete Amplifier Replacement

The official manuals express the remedy at two hardware levels:

• B-64305EN/03 instructs technicians to replace the spindle amplifier control printed circuit board.

• B-65285EN/04 states that the spindle amplifier or spindle amplifier control printed circuit board should be replaced.

These directions are compatible. The control PCB contains the affected control-circuit area, while a complete spindle amplifier replacement also replaces that board and the surrounding unit. The correct choice depends on the amplifier series, board availability, repair facilities and the procedure approved for the machine.

A control-board replacement may preserve the power section and reduce the amount of hardware changed, but it requires exact board compatibility and qualified service. A complete amplifier replacement may be the more practical choice when the board is not separately supported, the unit has other defects, or controlled board-level work is not available.

Before selecting either option, verify:

• The complete FANUC amplifier model and all suffixes

• The exact control-PCB part number when replacing the board separately

• Amplifier series, capacity and hardware specification

• Spindle software compatibility

• CNC, spindle motor and machine-builder configuration

• Connector layout and applicable commissioning procedure

Do not select a board or amplifier only from its appearance, nominal output or shortened base number. Similar FANUC units can use different control hardware or software support. An incompatible replacement may produce an amplifier-ID, software or parameter alarm even if alarm 32 disappears.

If a replacement is required, browse FANUC servo, spindle and power drives or send the complete model and suffix to REACO CNC for compatibility checking.

5. Replace Hardware Safely and Preserve the Configuration

Spindle amplifier work must be performed by qualified personnel with the machine isolated from all energy sources. Follow the discharge time, voltage checks, electrostatic-discharge precautions and removal instructions in the applicable FANUC and machine-builder manuals.

Before removing the original unit or PCB:

• Photograph connectors, board positions and settings

• Label every cable according to the machine drawing

• Preserve the original CNC and spindle parameter backup

• Record the original amplifier and control-board part numbers

• Confirm that the replacement has been tested and is compatible

Do not move boards between amplifiers while power is present. Do not touch charged DC-link or power terminals. If the service procedure requires transferring hardware, settings or software-related components, follow the exact manual for that amplifier rather than a generic spindle-drive procedure.

The alarm description does not authorize component-level modification of the LSI or its RAM in the machine. Board-level electronic diagnosis and repair require suitable test equipment and a controlled repair environment. On-site handling should follow the supported control-PCB or complete-unit replacement route.

6. Retest After Control Board or Amplifier Replacement

After installing the verified replacement, restore power according to the approved startup procedure and confirm:

• SP9032 and amplifier alarm 32 no longer appear

• The amplifier completes startup and reaches its expected ready state

• No amplifier-ID, software-mismatch or parameter alarm is generated

• The spindle responds correctly during the machine builder's controlled test

• All guards, interlocks, orientation and switching functions operate normally

Begin with the prescribed no-load test before returning the spindle to production. If a different alarm appears, record and diagnose the new number rather than continuing to label it SP9032.

If alarm 32 remains after a control-board replacement, stop repeated testing. Reconfirm the exact board compatibility, installation and applicable service procedure, and evaluate whether the complete spindle amplifier requires replacement. Do not compensate for a persistent alarm by altering unrelated parameters.

Difference Between SP9013, SP9016, SP9018 and SP9032

Several FANUC spindle alarms involve internal memory or self-checks, but they do not identify the same circuit or test.

These alarms can all lead to amplifier or control-board replacement, but their meanings should not be merged. Record the exact CNC message and amplifier display so the replacement decision uses the correct FANUC procedure.

Difference Between SP9024 and SP9032

This distinction prevents unnecessary cable replacement for an internal RAM fault and prevents premature amplifier replacement when the actual indication is alarm 24.

FANUC SP9032 Diagnostic Table

Recommended Troubleshooting Order

1. Confirm SP9032 / SSPA:32 SIC-LSI RAM FAULT on the CNC and 32 on the spindle amplifier.

2. Record the complete CNC, spindle amplifier and control-board models, including all suffixes, plus the spindle software information.

3. Confirm that the indication is alarm 32 rather than alarm 24 or another CNC, PMC, servo or spindle memory alarm.

4. Do not change spindle parameters, ladder logic, motor wiring, feedback cables or cutting conditions for a confirmed alarm 32.

5. Use the exact amplifier maintenance manual to determine whether the supported repair is control-PCB replacement, complete amplifier replacement or either option.

6. Verify the exact replacement part number, suffix, hardware series and software compatibility.

7. Isolate power, observe the required discharge time and replace the hardware using the approved procedure.

8. Power up the machine and confirm that the amplifier completes its startup self-check without alarm 32.

9. Perform the machine builder's controlled spindle test and verify all related safety and machine functions.

10. Diagnose any different alarm displayed after replacement as a separate condition.

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 32

• FANUC Series 0i-D/0i Mate-D Maintenance Manual, B-64305EN/03, SP9032 / SSPA:32 SIC-LSI RAM FAULT

• FANUC AC Servo Motor βi-B/βi Series, AC Spindle Motor βi Series, Servo Amplifier βi-B Series Maintenance Manual, B-65425 series, SP9032 alarm list

• Applicable spindle amplifier maintenance manual and machine-builder electrical/service documentation

• Beijing FANUC SP9032 technical guidance, serial communication LSI RAM fault

Always use the manual edition that applies to the exact CNC, spindle amplifier, control board, spindle software and machine configuration.

Need Help With FANUC SP9032 Alarm?

REACO CNC provides independent testing, repair, compatibility checking and replacement support for FANUC spindle amplifiers and control boards. Send us the CNC alarm screen, amplifier display, complete CNC and spindle amplifier models with suffixes, control-board model if available, spindle software information, and details of any recent board or amplifier work.

Visit the FANUC Technical Support Center for more FANUC alarm guides, or contact REACO CNC for assistance.

Reference Source: Beijing FANUC. This article is based on FANUC technical documentation. The correct control-board or complete-amplifier replacement and commissioning procedure depends on the exact spindle system and machine configuration.