SP9037 (Alarm 37) Speed Detector Parameter Error fault in Fanuc drive

SP9037 (Alarm 37) Speed Detector Parameter Error fault in Fanuc drive

Description

SP9037 (Alarm 37) is a configuration alarm on the Spindle Drive. It indicates a conflict in the parameter settings regarding the speed feedback device. The drive has parameters defining the number of pulses per revolution and the number of gear teeth (if using a magnetic sensor). If the drive detects signals that contradict these settings (e.g., receiving 128 pulses when it expects 256), Alarm 37 prevents rotation.

Cause

• Parameter Entry: Someone manually changed the spindle parameters (4000 series) and entered the wrong value for the sensor type.
• Gear Shift: The machine shifted gears (High/Low), but the proximity switch confirming the gear shift failed. The drive is using "Low Gear" parameters while the spindle is mechanically in "High Gear."
• Sensor Replacement: Replacing a 128-tooth sensor with a 256-tooth sensor without updating the drive.

Solution

1. Verify Gear State: Check the gearbox switches. Does the CNC know which gear it is in?
2. Check Params: Compare spindle parameters 4000-4139 against the backup. specifically the "Number of Gear Teeth" parameters.
3. Auto-Tuning: You may need to run the Spindle Parameter Initialization procedure if the motor was swapped.