Alarm 320 occurs when the Haas spindle drive unit detects an internal fault and sends a fault signal to the NGC control through the drive fault relay circuit. The drive protects itself by disabling output before the control displays this wrapper alarm, requiring direct inspection of the drive's fault display for the specific sub-code.
HaasProgram/G-codeAdvanced30 - 120 minutes
320
Haas 320 - NO FEED RATE | Haas CNC Alarm
NO FEED RATE
This alarm occurs when the control encounters a G-code motion command (G01, G02, G03) without an active feed rate value defined in the current modal state. The MOCON control requires an F-word feed rate to be programmed either on the same line or earlier in the program before any interpolated motion can execute. The machine will not begin the commanded move until a valid feed rate is established and the alarm is cleared.
Root Cause Summary
Alarm 320 occurs when the Haas spindle drive unit detects an internal fault and sends a fault signal to the NGC control through the drive fault relay circuit. The drive protects itself by disabling output before the control displays this wrapper alarm, requiring direct inspection of the drive's fault display for the specific sub-code.
Safety
Allow spindle to stop completely
Disconnect power to the machine before working on the spindle drive or motor. Lockout/Tagout procedures MUST be followed.
High voltages are present in the spindle drive and motor. Only qualified personnel should perform electrical testing and repairs.
Rotating machinery can cause serious injury. Keep hands and clothing away from the spindle during operation and testing.
Capacitors in the spindle drive can store a dangerous electrical charge even after power is removed. Allow sufficient time for discharge before touching any components.
Ensure proper grounding of the spindle drive, motor, and machine frame to prevent electrical shock.
Use appropriate personal protective equipment (PPE), including safety glasses, gloves, and insulated tools.
Wear appropriate personal protective equipment (PPE) and ensure the machine is isolated from power sources.
Causes and Fixes
1
Check Drive Fault Display
Open electrical cabinet and locate the spindle drive unit. Check the LED display or fault indicator on the drive face for specific fault codes (typically OC1, OC2, or OL codes).
Ensure main power is locked out before opening electrical cabinet
2
Verify Spindle Movement
With power off, manually rotate the spindle by hand to check for mechanical binding or rough bearing operation. Listen for grinding or unusual resistance.
Spindle should rotate smoothly with minimal resistance when cold
3
Check Motor Connections
Inspect U, V, W motor power cables at both the drive output terminals and spindle motor connection box for loose connections, corrosion, or damaged insulation.
Use proper lockout/tagout procedures and verify zero energy state
4
Test Motor Resistance
Using a multimeter, measure resistance between U-V, V-W, and W-U motor leads. Values should be balanced (typically 0.1-2 ohms) and check insulation resistance to ground.
Disconnect motor leads from drive before testing to avoid damaging drive electronics
1
Read Drive Fault Code
Check the spindle drive display for voltage-related fault codes such as UV (undervoltage), OV (overvoltage), or similar alphanumeric codes specific to your drive model.
Write down the exact fault code displayed as it will reset when power is cycled
2
Measure Input Voltage
Using a multimeter, measure the incoming AC voltage at the drive input terminals (typically L1, L2, L3). Verify voltage is within ±10% of nameplate rating (typically 208-240V or 480V).
Use appropriate PPE and follow electrical safety procedures when measuring live voltages
3
Check DC Bus Voltage
If accessible, measure the DC bus voltage across the drive's internal DC link capacitors. Should be approximately 1.35 times the AC input voltage for normal operation.
DC bus voltage should be stable - fluctuating readings indicate power supply issues
4
Inspect Power Connections
Check all incoming power connections at the main disconnect, transformer (if present), and drive input terminals for tightness, corrosion, or overheating signs.
Loose connections can cause voltage drops and arcing hazards
1
Check Drive Temperature Display
Look for temperature-related fault codes on the drive display such as OH (overheat), TH (thermal), or temperature values exceeding normal operating range (typically >70°C).
Some drives show actual temperature values - normal operating temperature is usually 40-60°C
2
Inspect Cooling System
Check drive cooling fans for proper operation, clean heat sinks of dust/debris buildup, and verify adequate airflow through the electrical cabinet ventilation system.
Allow drive to cool completely before handling heat sinks or internal components
3
Verify Cabinet Ventilation
Check electrical cabinet intake and exhaust fans, clean air filters, and ensure minimum 6-inch clearance around drive heat sinks for proper air circulation.
Cabinet temperature should not exceed 40°C ambient for proper drive operation
4
Check Drive Loading
Review recent machining operations for excessive spindle loads, rapid acceleration/deceleration cycles, or continuous high-speed operation that could cause thermal buildup.
Monitor drive current display during typical operations - consistently high current indicates overloading
1
Check Communication Cables
Inspect the serial communication cable (typically RS-485 or CAN bus) between the NGC control and spindle drive for damage, loose connections, or proper termination.
Communication cables should be shielded and routed away from power cables to prevent interference
2
Verify Drive Address Settings
Check that the spindle drive's communication address matches the setting expected by the NGC control (typically address 1 for spindle drive).
Incorrect addressing will prevent proper communication and cause faults
3
Test Communication Status
Access the NGC diagnostics menu and check communication status indicators for the spindle drive. Look for timeout errors or communication failure messages.
Use CURRENT COMMANDS display to verify spindle commands are being sent from control
4
Check Control Card Connections
Verify all connections to the NGC control's I/O cards, particularly the spindle interface card, and check for loose ribbon cables or damaged connectors.
Handle control cards with proper ESD precautions to prevent damage
1
Document Fault Information
Record the exact fault code displayed on the drive, any LED status indicators, and the circumstances when the fault occurred (startup, during operation, etc.).
Take photos of fault displays and drive nameplate information for service technician reference
2
Perform Drive Self-Test
If the drive has built-in diagnostic routines, run the self-test function to identify specific failed components or circuits within the drive unit.
Do not attempt to bypass drive safety circuits or force operation with hardware faults present
3
Check Drive Fuses
Inspect internal drive fuses (if accessible) and external fuses in the power circuit feeding the drive. Replace any blown fuses with exact same type and rating.
Blown fuses often indicate other component failures - investigate root cause before energizing
4
Contact Service Support
With hardware failures confirmed, contact Haas service support with drive model number, fault codes, and diagnostic results to arrange repair or replacement.
Attempting repairs on drive power circuits requires specialized training and equipment
DIY Feasiblemedium confidence
Call a technician if:
·Drive hardware failure confirmed
·Electrical measurements outside safe limits
·Multiple fault codes present
·Spindle motor replacement needed
Prevention
Maintain proper cabinet ventilation and clean air filters monthly
Monitor spindle loading to avoid continuous overload conditions
Perform regular electrical connection inspections
Keep drive firmware updated per Haas recommendations
Common Mistakes
Clearing alarm without reading drive fault code first
Ignoring temperature warnings before overheat fault
Replacing drive without checking motor and connections
