What causes FANUC alarm 352?

Synchronous control axis parameters (1010–1016, 8180–8183) have overlapping or conflicting axis assignments. A program attempts to activate synchronous control on an axis already grouped in another synchronous pair. After a control reset, the synchronous axis configuration was not properly cleared before re-pairing. Machine parameters were changed without a full power cycle to reinitialize synchronous axis relationships. Multiple synchronous control G-codes reference the same axis address in the same program block.

How do I fix FANUC alarm 352?

1. Review parameters 8180–8183 (or equivalent for your Fanuc model) which define synchronous control axis pairs — ensure no axis number appears in multiple sync groups. 2. Power cycle the CNC completely to reset synchronous control state and clear any latched axis groupings. 3. Check the part program for conflicting synchronous control commands affecting the same axis. 4. Verify parameter 1010 axis name assignments do not conflict with synchronous axis parameters. 5. Consult the machine builder parameters for synchronous axis configuration and compare against the Fanuc parameter manual.

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FANUC Controller

Program/G-code · Intermediate · 20-45 minutes

Alarm 352

Fanuc Alarm 352 - SYNCHRONOUS CONTROL AXIS COMPOSITION ERROR

Alarm 352 occurs when the CNC attempts to engage synchronous control (tandem, gantry, or coupled axis control) on an axis that is already participating in another synchronous, composite, or superimposed control mode. This is typically caused by conflicting parameter settings, ladder logic errors attempting multiple simultaneous control modes, or improper M-code/G-code commands that activate synchronous functions without properly releasing previous control states.

FANUCProgram/G-codeIntermediate20-45 minutes

352

Fanuc Alarm 352 - SYNCHRONOUS CONTROL AXIS COMPOSITION ERROR

SYNCHRONOUS CONTROL AXIS COMPOSITION ERROR

Root Cause Summary

Alarm 352 occurs when the CNC attempts to engage synchronous control (tandem, gantry, or coupled axis control) on an axis that is already participating in another synchronous, composite, or superimposed control mode. This is typically caused by conflicting parameter settings, ladder logic errors attempting multiple simultaneous control modes, or improper M-code/G-code commands that activate synchronous functions without properly releasing previous control states.

Safety

Multiple axes may be affected
Check all axis positions after repair
Electrical Hazard: Ensure power is disconnected before working on electrical components. High voltages are present in amplifiers and CNC cabinets.
Mechanical Hazard: Axes may move unexpectedly after power is restored. Keep clear of moving parts.
Laser Hazard: Fiber optic cables may transmit laser light. Avoid looking directly into the ends of disconnected fiber cables.
Electrostatic Discharge (ESD) Hazard: Use proper ESD grounding techniques when handling electronic components, especially the FSSB card and amplifiers.

Causes and Fixes

1
Navigate to SYSTEM > PARAM and check parameter 1023 (axis number for tandem control master), 1024 (superimposed control axis configuration), and 1028 (composite control axis). Verify that the alarm axis is not defined in multiple parameters simultaneously.
2
Check parameter 1033 (synchronous control type): bit 0 for tandem, bit 1 for gantry. Ensure only one synchronous mode is enabled per axis group. Record current settings before making changes.
Parameter changes require PWE (parameter write enable) bit 0 of parameter 8000 set to 1. Power cycle is required after synchronous control parameter changes.
3
Verify axis coupling parameters 1022 (coupled axis number) does not overlap with synchronous control axis definitions. Cross-reference all axes involved in the error message.
4
After correcting conflicting parameters, perform a full power cycle (not emergency stop reset). Verify synchronous operation with single axis jog before running programs.

DIY Feasiblehigh confidence

Call a technician if:

·Parameter changes required beyond basic sync control
·FSSB hardware issues detected
·Persistent alarms after all troubleshooting steps

Prevention

Always use G51.1 P0 to cancel synchronous control before starting new sync operations
Verify axis control states before implementing synchronous control
Implement proper program structure with sync control pairing

Common Mistakes

Forgetting to cancel previous synchronous control with G51.1 P0
Attempting sync control on axes with active composite control
Not checking FSSB communication status before troubleshooting

Related Alarms

351 353 400 401

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