Kollmorgen AKD Fault Codes

F502: Bus under voltage

What it means: The DC bus voltage dropped below the undervoltage threshold. With the default setting the drive first shows warning n502 while disabled, and trips on F502 when it is enabled (or someone tries to enable it) during the undervoltage. The drive does a controlled stop.^{[1][2][3][5][6]}

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Main AC supply off or lost while the 24 V control power stays on (open main contactor, E-stop circuit, tripped breaker or blown fuse)
• Low or sagging mains voltage, or a missing supply phase
• Drive enabled before the DC bus finished charging
• Undervoltage level set higher than the real supply allows

First checks, in this order

1. Measure the mains voltage at the drive power input and check fuses, breaker and main contactor.
2. Read the actual DC bus voltage with VBUS.VALUE in WorkBench.
3. Check the switch-on order: main power on and bus charged before the enable signal.
4. Check VBUS.UVMODE (1 = fault only when enabled, 0 = fault any time) and the trip level VBUS.UVFTHRESH.
5. Clear with DRV.CLRFAULTS once the bus voltage is back to normal.

F501: Bus over voltage

What it means: The DC bus voltage went too high, usually while the motor is braking a load and pushing energy back into the drive. Warning n501 can come first. The drive disables the power stage.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Deceleration too fast for the load inertia
• Regen (braking) resistor missing, undersized, wired wrong or set up wrong
• Mains voltage too high

First checks, in this order

1. Reduce the load or soften the motion profile, for example a longer deceleration.
2. Check the regen resistor, its wiring and its settings (REGEN.TYPE, REGEN.REXT). Add regen capacity if needed.
3. Check the mains voltage.
4. Read the trip level with VBUS.OVFTHRESH and compare with VBUS.VALUE while the axis brakes.

n501: Bus over voltage

What it means: Early warning that the DC bus voltage is high. The drive keeps running, but F501 follows if the voltage keeps rising.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Hard braking of a high inertia load
• Regen resistor capacity too small
• High mains voltage

First checks, in this order

1. Lengthen the deceleration or reduce the load.
2. Check the regen resistor and add capacity if needed.
3. Check the mains voltage.

F525: Output over current

What it means: Motor output current went above the drive's peak current. The drive disables the power stage at once.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Short circuit in the motor cable or motor windings
• Feedback fault giving the drive a wrong position, so it drives current the wrong way
• Wrong motor data or badly tuned current loop

First checks, in this order

1. With power off and the bus discharged, check the motor cable and motor phases for shorts and shorts to ground.
2. Look for feedback faults in the fault history and check the feedback cable.
3. Check the motor parameters match the motor nameplate.

F602: Safe torque off

What it means: The Safe Torque Off (STO) input was switched off, so the drive removed torque from the motor and disabled the power stage.^[1][3][8]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• E-stop, guard door or safety relay opened the STO circuit
• STO 24 V supply missing or a loose STO wire
• On two-channel drives (AKD-x048), only one of STO1 or STO2 is on

First checks, in this order

1. Check why the safety circuit opened (E-stop, door switch, safety relay).
2. Read STO.STATE: 1 means torque is allowed, 0 means STO is active. On AKD-x048, 3 means both channels on.
3. Reapply the STO supply voltage only if it is safe to do so, then clear the fault and enable.

d2: Firmware download: Corrupted operational FPGA; resident FPGA is functional

What it means: Display code, not an F fault: the drive is stuck in firmware download mode because its operational FPGA image is corrupt. The backup (resident) image still works, so the drive can usually be recovered by loading firmware again.^[4][2]

Likely causes

• A firmware download that was interrupted or failed
• Power loss on the 24 V control supply during a firmware update
• Wrong or incompatible firmware file

First checks, in this order

1. Connect WorkBench and download the correct firmware for this drive model again.
2. Keep the 24 V control power steady during the whole download.
3. If d2 comes back after a clean download, contact Kollmorgen support.

F401: Failed to set feedback type

What it means: The drive cannot set up the motor feedback device. The feedback is not connected, or the wrong feedback type is selected. The drive brakes the motor dynamically.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Feedback cable unplugged or damaged at X10 or at the motor
• Wrong feedback type selected in WorkBench
• Motor or feedback device replaced with a different type

First checks, in this order

1. Check the primary feedback cable and connector at X10 and at the motor.
2. Check the feedback type setting in WorkBench matches the motor.
3. Clear the fault; this re-initializes the feedback.

F402: Analog signal amplitude fault

What it means: The sine and cosine signals from the feedback (resolver, sine/cosine encoder, EnDat 2.1 and similar) are too weak or too strong. The drive brakes the motor dynamically.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Damaged feedback cable or bad connector pins
• Poor shielding or noise on the feedback cable
• Faulty resolver or encoder

First checks, in this order

1. Check the primary feedback wiring at X10 (resolver and sine/cosine encoders).
2. Check cable shield connections and keep the feedback cable away from motor power cables.
3. Swap in a known good feedback cable to rule out the cable.

F403: EnDat communication fault

What it means: The drive lost reliable communication with an EnDat encoder. The drive brakes the motor dynamically.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Feedback cable damage or loose connector
• Noise on the feedback cable
• Linear EnDat scale not calibrated

First checks, in this order

1. Check the primary feedback connection at X10.
2. If the feedback is linear, check its calibration.
3. Clear the fault and watch whether it returns when the cable is moved.

F404: Illegal Hall state (111, 000)

What it means: The Hall sensors report all on or all off, which can never happen on a working motor. Usually one Hall signal wire is broken. The drive brakes the motor dynamically.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Broken wire in one of the Hall signals
• Pushed-back or loose pin in a feedback connector
• Hall sensor supply missing

First checks, in this order

1. Check the feedback wiring end to end.
2. Check every feedback connector pin is fully seated.
3. Valid Hall states are 001, 011, 010, 110, 100 and 101; turn the motor by hand and watch the state in WorkBench.

F405: BiSS watchdog fault

What it means: Communication with a BiSS feedback device failed. The drive brakes the motor dynamically.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Feedback cable or connector problem
• Noise on the feedback line
• Faulty BiSS encoder

First checks, in this order

1. Check the primary feedback connection at X10 (BiSS only).
2. Check the shield and routing of the feedback cable.
3. Replace the cable or encoder if the fault keeps coming back.

F417: Broken wire in primary feedback

What it means: The drive detected a broken wire in the primary feedback, seen as a loss of incremental encoder signal amplitude. The drive brakes the motor dynamically.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Broken conductor in the feedback cable, often in a cable chain
• Loose or damaged connector

First checks, in this order

1. Check feedback cable continuity, conductor by conductor.
2. Flex the cable along its path while watching for the fault, then replace the damaged cable.

F418: Primary feedback power supply

What it means: The power supply for the primary feedback device has a fault. The drive brakes the motor dynamically.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Short in the feedback cable or encoder supply wires
• Faulty encoder drawing too much current

First checks, in this order

1. Check the primary feedback connection at X10.
2. Unplug the feedback cable and see whether the fault clears, then test the cable and encoder separately.

F419: Encoder init procedure failed

What it means: The phase finding (commutation set-up) procedure for the encoder did not finish. The drive disables the power stage.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Encoder wiring problem
• Load too heavy or unbalanced during phase finding

First checks, in this order

1. Check the encoder wiring.
2. Reduce or balance the motor load before running phase finding again.

F438: Deviation from predicted trajectory fault

What it means: Following error: the motor did not follow the commanded motion and went past the drive's maximum allowed (numeric) position error. Warning n438 can come first. The drive does a controlled stop.^[1][3][2]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• More load than usual, a jam or a sticking axis
• Position error limit set too tight
• Current or velocity limits holding the motor back

First checks, in this order

1. Check the mechanics for jamming, sticking or a dragging brake.
2. Check whether the position error limit is set too low.
3. Check that IL.LIMITP, IL.LIMITN, VL.LIMITP and VL.LIMITN are not limiting the drive.

F439: Following error magnitude fault

What it means: Following error: the position error went above the user limit set in PL.ERRFTHRESH. Warning n439 can come first (warning level PL.ERRWTHRESH). The drive does a controlled stop.^[1][3][7][2]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Axis blocked, overloaded or binding
• Poor tuning or wrong commutation set-up
• Motor or drive too small for the move, or current limits set too low
• PL.ERRFTHRESH set tighter than the process needs

First checks, in this order

1. Check the mechanics for binding or a crash.
2. Check the feedback commutation set-up and the tuning parameters.
3. Check PL.ERRFTHRESH (0 switches the check off, which is not recommended for safety).
4. Verify motor and drive sizing, and that IL.LIMITP/IL.LIMITN and VL.LIMITP/VL.LIMITN are not limiting the drive.

F451: Feedback battery fault

What it means: The external battery that keeps the multiturn encoder position is too low. F451 is set when the battery ran low while the drive was off; n451 is the warning when the drive is powered. The drive brakes the motor dynamically.^[1][3][10]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Encoder backup battery worn out
• Battery disconnected or battery wiring fault

First checks, in this order

1. Check or replace the external encoder battery.
2. After a battery loss, check the axis position and home it again if needed.
3. FAULT451.ACTION can suppress this fault; only change it if the application does not need the stored position.

F467: Feedback fault on feedback 1

What it means: The primary feedback device reported a malfunction. For HIPERFACE DSL and SFD3 feedback, FB1.FAULTS gives the root cause. With BiSS feedback this fault means a communication fault. The drive brakes the motor dynamically.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Encoder internal error
• Feedback cable or connector problem
• Communication fault with a BiSS device

First checks, in this order

1. Read FB1.FAULTS in the WorkBench terminal for the detailed cause.
2. Check the feedback cable and connectors.
3. Replace the motor feedback if FB1.FAULTS points to an internal device error.

F480: Field bus command velocity too high

What it means: The speed commanded over the fieldbus is above the positive velocity limit VL.LIMITP. The drive disables the power stage.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Controller trajectory asks for more speed than the drive allows
• VL.LIMITP set too low for the application

First checks, in this order

1. Lower the commanded trajectory in the controller.
2. Or raise VL.LIMITP if the motor and machine allow it.

F493: Invalid commutation detected

What it means: The motor accelerated the wrong way compared with the current the drive applied, which points to a wrong commutation angle or swapped motor phases. The drive brakes the motor dynamically.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Motor phases wired in the wrong order
• Bad commutation angle from Wake and Shake
• Wrong feedback set-up after a motor or encoder change

First checks, in this order

1. Check the motor phase wiring U, V, W.
2. Re-configure Wake and Shake (if mode 0 or 1 is used) and run it again to find the correct commutation angle.
3. Check thresholds WS.CHECKV and WS.CHECKT if the fault appears on a correctly wired axis.

F301: Motor overheated

What it means: The motor temperature sensor reports the motor is too hot. Warning n301 can come first. The drive disables the power stage.^{[1][3][11][2]}

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Motor running above its rating
• High ambient temperature or poor heat sinking of the motor mount
• Motor current settings wrong
• Temperature threshold MOTOR.TEMPFAULT set wrong

First checks, in this order

1. Check the ambient temperature around the motor.
2. Check how well the motor mounting carries heat away.
3. Verify motor and drive sizing and that the continuous and peak current settings are correct.
4. Check MOTOR.TEMPFAULT (resistance threshold; 0 switches the fault off). With MOTOR.AUTOSET = 1 it is set automatically for Kollmorgen motors.

n301: Motor overheated

What it means: Early warning that the motor is getting too hot. The drive keeps running, but F301 follows if the temperature keeps rising.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Heavy duty cycle
• Poor motor cooling or high ambient temperature

First checks, in this order

1. Reduce the load or duty cycle if you can.
2. Check the ambient temperature and the motor mounting.
3. Plan a stop to find the cause before F301 trips the axis.

F302: Over speed

What it means: The motor went faster than the overspeed limit. The user limit is VL.THRESH; the overall limit is the lower of VL.THRESH and 1.2 x MOTOR.VMAX. The drive brakes the motor dynamically.^[1][3][9]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Velocity command above VL.THRESH
• Overshoot from aggressive tuning
• Load driving the motor (for example an overhauling axis)
• Feedback or commutation problem

First checks, in this order

1. Lower the velocity command or raise VL.THRESH if the motor and machine allow it.
2. Check the tuning for overshoot.
3. Check feedback wiring if the fault appears at normal speeds.

F303: Run away

What it means: The motor did not follow the command values: the current command stayed too high for too long. The drive does a controlled stop.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Servo gains too high
• Command trajectory too aggressive
• Mechanical problem or wrong feedback set-up

First checks, in this order

1. Reduce the servo gains.
2. Make the commanded trajectory less aggressive.
3. Check the mechanics and the feedback set-up.

F304: Motor Foldback

What it means: The motor reached its maximum power and the drive folded back (limited) the current to protect the motor. Warning n304 comes first. The drive does a controlled stop.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Motion needs more power than the motor can give
• Load jamming or sticking
• Current limits set wrong

First checks, in this order

1. Change the move profile to reduce the load on the motor.
2. Check the axis for jamming or sticking.
3. Check that the current limits are set correctly.

n304: Motor Foldback

What it means: The drive is limiting motor current to protect the motor from overload. The axis may run slower or weaker than commanded.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Duty cycle too heavy for the motor
• Mechanical drag or a partial jam

First checks, in this order

1. Check for drag or binding in the mechanics.
2. Reduce accelerations or the duty cycle.
3. Check the current limit settings.

F524: Drive Foldback

What it means: The drive reached its own maximum power and limited the output to protect itself. Warning n524 comes first. The drive does a controlled stop.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Motion needs more power than the drive can deliver
• Drive too small for the duty cycle
• Mechanical overload

First checks, in this order

1. Change the motion profile to reduce the load.
2. Check the mechanics for binding.
3. Verify the drive size against the real peak and continuous current.

n524: Drive Foldback

What it means: The drive is limiting its output current to protect itself. The axis keeps running but may lose performance.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Heavy duty cycle near the drive's rating
• Mechanical drag

First checks, in this order

1. Reduce accelerations or the duty cycle.
2. Check the mechanics for drag.
3. Check that the drive is sized for the application.

F309: Motor I2t load over fault threshold

What it means: The calculated motor load (IL.MI2T) went over the fault threshold IL.MI2TFTHRESH. This only happens when motor protection mode IL.MIMODE is set to 1. The drive disables the power stage.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Motor overloaded over time
• Acceleration and deceleration ramps too steep

First checks, in this order

1. Reduce the load, for example with gentler acceleration and deceleration ramps.
2. Check IL.MI2TFTHRESH and IL.MIMODE.

n309: Motor I2t load. reduce load

What it means: The calculated motor load (IL.MI2T) passed the warning threshold IL.MI2TWTHRESH (only with IL.MIMODE = 1). The drive keeps running.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Heavy duty cycle
• Steep acceleration and deceleration ramps

First checks, in this order

1. Lower the acceleration and deceleration ramps.
2. Check IL.MI2TWTHRESH.

F314: Motor phase loss detected

What it means: One or more motor phase lines are not properly connected. The drive disables the power stage.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Loose or unplugged motor connector
• Broken motor cable conductor
• Open motor contactor between drive and motor

First checks, in this order

1. With power off and the bus discharged, check the motor connector and wiring at the AKD.
2. Check the motor cable and any motor contactor for an open phase.

F315: Temperature sensor connection fault

What it means: The motor temperature sensor in the feedback is disconnected or faulty. The drive disables the power stage.^[3]

Likely causes

• Temperature sensor wires open in the feedback cable
• Faulty motor temperature sensor

First checks, in this order

1. Check the temperature sensor connection.
2. Measure the sensor resistance.

F234: Control over temperature sensor 1

What it means: The control board temperature sensor reached its high limit. Warning n234 can come first. The drive disables the power stage.^[3][1]

Also on: AKD BASIC (AKD Fault Card lists F234 to F237 as Temperature sensor high)

Likely causes

• Cabinet too hot
• Poor cabinet ventilation or blocked air flow around the drive

First checks, in this order

1. Check the cabinet ventilation and cooling.
2. Read DRV.TEMPERATURES to see control and power board temperatures.

F235: Power over temperature sensor 1

What it means: The power stage temperature sensor reached its high limit. Warning n235 can come first. The drive disables the power stage.^[3][1]

Also on: AKD BASIC (AKD Fault Card lists F234 to F237 as Temperature sensor high)

Likely causes

• Cabinet too hot or poor air flow
• Drive running near or above its current rating

First checks, in this order

1. Check the cabinet ventilation and cooling.
2. Read DRV.TEMPERATURES.
3. Check the load and duty cycle against the drive rating.

F535: Power-board over-temperature fault

What it means: The power board temperature sensor reads more than 85 °C. The drive disables the power stage.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Load too high for the drive
• Poor cooling or high cabinet temperature

First checks, in this order

1. Reduce the load on the drive.
2. Improve cooling and check air flow around the drive.
3. Read DRV.TEMPERATURES.

n258: Fan not spinning

What it means: The drive's cooling fan is not spinning correctly. The drive keeps running but can overheat.^[3]

Likely causes

• Failed or blocked cooling fan

First checks, in this order

1. Restart the drive.
2. If the warning stays, exchange the drive (per Kollmorgen) and watch drive temperatures with DRV.TEMPERATURES meanwhile.

F503: Bus capacitor overloaded

What it means: The DC bus capacitors are overloaded, typically from single-phase input on a drive rated only for three-phase, or too much load on single phase. The drive does a controlled stop.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Single-phase supply on a drive that needs three-phase
• Missing supply phase
• Too much load on a single-phase supply

First checks, in this order

1. Check the mains voltage on all phases.
2. Check the drive rating plate for single-phase or three-phase input.

F519: Regen short circuit

What it means: Short circuit in the regen (braking) resistor circuit or the regen transistor. The drive disables the power stage.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Shorted regen resistor or wiring
• Failed regen transistor in the drive

First checks, in this order

1. With power off and the bus discharged, check the regen resistor and its wiring.
2. If the wiring is good, contact Kollmorgen technical support.

F521: Regen over power

What it means: Too much braking energy went into the regen resistor. Warning n521 can come first. The drive disables the power stage.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Regen resistor too small for the braking duty
• Frequent hard stops of a high inertia load

First checks, in this order

1. Fit a larger regen resistor, or use DC bus sharing to spread the energy.
2. Check REGEN.TYPE and REGEN.REXT match the fitted resistor.
3. Lengthen deceleration ramps if the process allows.

F560: Regen near capacity, could not prevent over voltage

What it means: A bus over voltage (F501) happened while the regen resistor was already at 75% or more of its capacity. The drive disables the power stage.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Regen resistor too small for the braking energy

First checks, in this order

1. Fit a larger regen resistor that can dissipate more power.
2. Check the regen resistor settings in REGEN.TYPE and REGEN.REXT.

F526: Current sensor short circuit

What it means: The drive sees a short on a current sensor. Kollmorgen also lists a motor cable plugged in upside down as a cause. The drive disables the power stage.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Motor cable connector plugged in upside down
• Current sensor hardware fault

First checks, in this order

1. Check the motor connector is plugged in the right way up.
2. Restart the drive; if the fault stays, contact technical support.

F531: Power stage fault

What it means: The drive detected a hardware failure in its power stage. The drive disables the power stage.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Internal power stage hardware failure
• Damage after a motor cable short

First checks, in this order

1. Check the motor cable and motor for shorts before powering again.
2. Restart the drive; if the fault stays, replace the drive.

F532: Drive motor parameters setup incomplete

What it means: The minimum set of motor parameters has not been configured, so the drive will not enable. Common on a new or replaced drive.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• New or reset drive without motor data
• Motor without feedback memory and MOTOR.AUTOSET not used

First checks, in this order

1. Send DRV.SETUPREQLIST to list the parameters still needed.
2. Set them with the setup wizard, by picking the motor from the WorkBench motor database (with MOTOR.AUTOSET = 0), or one by one.
3. For motors with feedback memory (BiSS Analog, EnDat, SFD), set MOTOR.AUTOSET = 1 so the drive reads them.

F534: Failed to read motor parameters from feedback device

What it means: The drive could not read motor data from the feedback memory. The motor may have no feedback memory, or the memory is not programmed. The drive brakes the motor dynamically.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Motor without feedback memory while MOTOR.AUTOSET = 1
• Feedback memory not programmed
• Feedback communication problem

First checks, in this order

1. Click Disable and Clear Faults, or send DRV.CLRFAULTS, to try the read again.
2. If it fails, set MOTOR.AUTOSET to 0 and enter the motor data with the setup wizard or by hand.
3. For a motor that should have memory (BiSS Analog, EnDat, SFD), return it to have the memory programmed.

F305: Brake open circuit

What it means: The motor holding brake circuit is open. The fault threshold is 200 mA. The drive brakes the motor dynamically.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Brake wires broken or not connected
• Faulty brake coil
• Special low current brake below the 200 mA threshold

First checks, in this order

1. Check the brake cabling and the brake itself.
2. For special low current brakes, Kollmorgen allows bypassing F305 with MOTOR.BRAKE = 100.

F306: Brake short circuit

What it means: The motor holding brake circuit is shorted. The drive brakes the motor dynamically.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Shorted brake wires or brake coil
• Brake timing parameters not set

First checks, in this order

1. Check the brake cabling and the brake coil.
2. Check that MOTOR.TBRAKERLS and MOTOR.TBRAKEAPP are configured.

F307: Brake applied during Enable-State

What it means: The motor holding brake closed unexpectedly while the drive was enabled. The drive brakes the motor dynamically.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Brake wiring fault or intermittent connection
• Brake power supply dropping out

First checks, in this order

1. Check the brake cabling and connectors.
2. Check the 24 V supply that powers the brake for dips under load.

F245: External Fault

What it means: A digital input set as an external fault input (DINx.MODE = 10) went active. The cause is outside the drive. The drive disables the power stage.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• A machine device wired to the external fault input has tripped
• Broken wire on that input

First checks, in this order

1. Find which input has DINx.MODE = 10 and what device drives it.
2. Fix the external device, then clear the input to clear the fault.

F701: Fieldbus Runtime

What it means: A fieldbus communication fault happened during runtime. The drive does a controlled stop.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Fieldbus cable or connector problem
• Wrong fieldbus settings
• Controller (master) problem

First checks, in this order

1. Check the fieldbus connections, the settings and the control unit.

F702: Fieldbus Communication lost

What it means: All fieldbus communication was lost. Warning n702 can come first. The drive does a controlled stop.^[1][3][10]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Fieldbus cable unplugged or damaged
• Controller stopped or rebooted
• Network switch or settings problem

First checks, in this order

1. Check the fieldbus connections, the settings and the controller.
2. Check FAULT702.ACTION (0 disables the drive, 1 ignores the fault).

n702: Fieldbus Communication lost

What it means: Warning that fieldbus communication was lost. The drive is not tripped yet, but the controller can no longer command it.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Fieldbus cable or connector problem
• Controller not communicating

First checks, in this order

1. Check the fieldbus cable, connectors and controller status.

F706: Fieldbus cyclic setpoints missing

What it means: The fieldbus master stopped sending setpoints within the timeout. Warning n706 can come first. The drive does a controlled stop.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Controller program stopped or overloaded
• Fieldbus wiring problem

First checks, in this order

1. Check the fieldbus connection and wiring.
2. Check that the controller is running and sending cyclic setpoints.

n107: Positive limit switch triggered

What it means: The positive hardware limit switch input (DINx.MODE 18) is off, or the position passed the positive software limit. The drive does a controlled stop in that direction.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Axis ran onto the positive limit switch
• Limit switch wiring open
• Software limit (SWLS.EN, SWLS.LIMIT0 or SWLS.LIMIT1) set wrong

First checks, in this order

1. Move the load away from the limit.
2. Check the limit switch and its wiring.
3. Check the software limit settings SWLS.EN, SWLS.LIMIT0 and SWLS.LIMIT1 against PL.FB.

n108: Negative limit switch triggered

What it means: The negative hardware limit switch input (DINx.MODE 19) is off, or the position passed the negative software limit. The drive does a controlled stop in that direction.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Axis ran onto the negative limit switch
• Limit switch wiring open
• Software limit set wrong

First checks, in this order

1. Move the load away from the limit.
2. Check the limit switch and its wiring.
3. Check SWLS.EN, SWLS.LIMIT0 and SWLS.LIMIT1 against PL.FB.

F106: NV Memory Data

What it means: Data in the drive's non-volatile memory is corrupt or invalid. Right after a firmware download this is expected and not a sign of a problem. The drive disables the power stage.^[1][3]

Also on: AKD BASIC (same code in the AKD Fault Card)

Likely causes

• Recent firmware download
• Corrupted parameter memory

First checks, in this order

1. After a firmware download: clear the fault and save the parameters to the drive.
2. Otherwise, reset the drive to default memory values with Parameter Load in WorkBench, then reload the machine's parameter file.

F01: Heat Sink Temperature

What it means: S300/S700: the heat sink temperature is too high. The factory limit is 80 °C (parameter MAXTEMPH).^[12][13]

Also on: S300 and S700 (not AKD); the Kollmorgen article also covers S400 and S600

Likely causes

• Ambient temperature too high
• Dirty drive or blocked ventilation slots
• Fan failed or not connected
• MAXTEMPH set too low
• Too little air flow because of tight installation

First checks, in this order

1. Lower the cabinet temperature.
2. Clean the ventilation slots and use air filters.
3. Listen for the fan and check air flow; send the drive for repair if the fan has failed.
4. Check MAXTEMPH (range 20 to 85 °C, default 80 °C).

F02: Overvoltage

What it means: S300/S700: overvoltage in the DC bus link. The limit depends on the mains voltage setting. Warning n02 (regen power) often shows first.^[12][14]

Also on: S300 and S700 (not AKD); the Kollmorgen article also covers S400 and S600

Likely causes

• Braking energy too high
• Mains voltage set too low in the drive
• Brake resistor set up or wired wrong, or its fuse blown
• Braking ramps too short

First checks, in this order

1. Set the mains voltage correctly on the Basic Setup screen.
2. Check the brake resistor settings and wiring: the bridge stays in for the internal resistor and comes out for an external one.
3. Replace a blown brake resistor fuse.
4. Lengthen the braking ramps, add an external brake resistor, or link DC buses of several drives.

F03: Following Error

What it means: S300/S700: following error from the position controller (OPMODE 5 or 6 only). The axis did not keep up with the commanded position.^[12][15]

Also on: S300 and S700 (not AKD); the Kollmorgen article also covers S400 and S600

Likely causes

• Axis mechanically tight or blocked
• Not enough torque for the ramps
• Gains too low or too high
• IPEAK too low

First checks, in this order

1. Check the mechanics.
2. Use flatter ramps (ACC, DEC).
3. Adjust the velocity and position loop gains.
4. Enlarge the following error window, raise IPEAK, or use a larger drive or motor.

F04: Feedback

What it means: S300/S700: feedback error, such as a cable break, short circuit or short to ground. The display may also show an extra i code (ERRCODE2) with detail, for example i53 for low resolver amplitude.^[12][16]

Also on: S300 and S700 (not AKD); the Kollmorgen article also covers S400 and S600

Likely causes

• Damaged, wrong or too long feedback cable
• Bad contacts in the connector
• Defective feedback device
• Wrong or incompatible feedback type (FBTYPE)
• Poor shielding or noise from power cables
• New encoder data never initialized

First checks, in this order

1. Check the feedback cable and connector contacts, especially in cable chains.
2. Check FBTYPE matches the motor feedback.
3. Check shielding and spacing between power and signal cables, and the maximum cable length.
4. For a new encoder, initialize its data with HSAVE in the terminal.
5. Exchange the feedback or motor if it is defective.

F05: Undervoltage

What it means: S300/S700: undervoltage in the DC bus link (default limit 100 V).^[12][17]

Also on: S300 and S700 (not AKD); the Kollmorgen article also covers S400 and S600

Likely causes

• Mains contactor not switched on
• Wrong switch-on order (enable before mains power)
• Emergency stop cut the mains voltage
• VBUSMIN set too low or too high for the application

First checks, in this order

1. Check the mains contactor wiring, emergency stop and control logic.
2. Switch on the power contactor (via the BTB contact) first, then the enable about 0.5 s later.
3. Check VBUSMIN, for example in 48 V DC applications.
4. Where the axis must move during a mains failure, UVLTMODE 0 switches the supervision off.

F06: Motor Temperature

What it means: S300/S700: motor temperature too high, or the temperature sensor is defective.^[12][18]

Also on: S300 and S700 (not AKD); the Kollmorgen article also covers S400 and S600

Likely causes

• Motor overheating from wrong motor parameters or poor cooling
• Defective temperature sensor
• Loose feedback connector or broken feedback cable
• MAXTEMPM threshold set too low

First checks, in this order

1. Check the motor parameters and cooling.
2. Measure the sensor resistance (a switch is closed when cold and open when hot).
3. Check the feedback connector and cable.
4. Check MAXTEMPM; for a motor without a sensor fit a jumper or set MAXTEMPM to 0.

F08: Overspeed

What it means: S300/S700: the motor runs away and the speed is too high.^[12][19]

Also on: S300 and S700 (not AKD); the Kollmorgen article also covers S400 and S600

Likely causes

• Speed above the VOSPD limit
• Overshoot from gain settings
• Defective feedback cable
• Motor phases inverted or MPHASE offset wrong
• Feedback of another motor connected

First checks, in this order

1. Check VOSPD and raise it if needed.
2. Shake the feedback cable while watching for the fault, and replace it if faulty.
3. Check the motor phase pin assignment and MPHASE.
4. Check that each drive has the correct motor and feedback cable.

F12: Motor Phase

What it means: S300/S700: a motor phase is missing, for example from a cable break.^[12][20]

Also on: S300 and S700 (not AKD); the Kollmorgen article also covers S400 and S600

Likely causes

• Motor connector not plugged in at the drive or motor
• Motor contactor switching late or with burnt contacts
• Bad motor cable shield or strong EMC noise
• Motor cable capacitance too high

First checks, in this order

1. Check the motor connectors.
2. Check any motor contactor and its timing.
3. Check the motor cable shield connections.
4. Use a motor choke or a shorter cable if the cable is long.

F14: Output Stage

What it means: S300/S700: fault in the power output stage, also caused by a wrong motor cable or poor cable shielding.^[12][21]

Also on: S300 and S700 (not AKD); the Kollmorgen article also covers S400 and S600

Likely causes

• Short circuit in the motor cable
• Insulation fault in the motor
• Motor contactor switching late or with burnt contacts
• Short in the external brake resistor circuit
• Motor cable shield not connected, or auxiliary supply too low
• Failed output stage

First checks, in this order

1. Measure between motor phases with an ohmmeter: readings must be equal. Each phase to PE must read open.
2. Check the motor contactor and the external brake resistor wiring.
3. Connect the motor cable shield at both ends.
4. Check the auxiliary power supply level.
5. If all checks pass, return the drive for repair.

F15: I²t max.

What it means: S300/S700: the I²t (current over time) maximum was exceeded, so the motor or drive was overloaded.^[12][22]

Also on: S300 and S700 (not AKD); the Kollmorgen article also covers S400 and S600

Likely causes

• Axis mechanically tight
• Ramps too steep or rest times between moves too short
• Wrong phase angle (MPHASE) between feedback and motor
• Faulty feedback cable or loose feedback device
• Current loop oscillation or a partial winding short

First checks, in this order

1. Check the mechanics; use a larger drive or motor if needed.
2. Lengthen the ramps (ACC, DEC) and the rest times between motion tasks.
3. Correct MPHASE.
4. Check and repair the feedback cable.

F16: Mains BTB/RTO

What it means: S300/S700: two or three phases are missing in the mains supply.^[12][23]

Also on: S300 and S700 (not AKD); the Kollmorgen article also covers S400 and S600

Likely causes

• Phases missing because of wiring, fuses or the main contactor
• Three-phase operation set while the drive is fed single-phase
• Drive enabled with no mains voltage

First checks, in this order

1. Check wiring, fuses and the main contactor.
2. Check the supply setting on the Basic Setup screen.
3. Enable the drive only after mains voltage is on.

F25: Commutation Error

What it means: S300/S700: commutation error; the motor may have oversped because current and motion are in opposite directions. An extra i code (ERRCODE2) can give detail.^[12][24]

Also on: S300 and S700 (not AKD); the Kollmorgen article also covers S400 and S600

Likely causes

• Motor phase or feedback wiring error
• Motor or feedback cable from another axis plugged in
• Wrong MRESPOLES, MPOLES or MPHASE
• Wake and Shake failed
• Supervision too sensitive (VCOMM)

First checks, in this order

1. Test the motor cable and feedback cable fully, and adjust DIR if needed.
2. Check that each drive has the right motor and feedback cable.
3. Check MRESPOLES, MPOLES and MPHASE.
4. Run Wake and Shake again if used.
5. Raise VCOMM if the supervision trips on a correct axis.

F27: STO

What it means: S300/S700: STO operating error: the STO-Enable input and ENABLE were set at the same time (or STO-Enable came later).^[12][25]

Also on: S300 and S700 (not AKD); the Kollmorgen article also covers S400 and S600

Likely causes

• Wrong switch-on order of STO-Enable and ENABLE
• Cable fault in the STO circuit

First checks, in this order

1. Follow the switch-on order: STO-Enable first, then ENABLE (see the instructions manual).
2. Check the STO wiring and measure the cable resistance.

n01: I²t

What it means: S300/S700: the I²t threshold was exceeded. The output stage stays on, but F15 can follow if the overload continues.^[12]

Also on: S300 and S700 (not AKD)

Likely causes

• Heavy duty cycle
• Mechanical drag or steep ramps

First checks, in this order

1. Check the mechanics for drag.
2. Lengthen the ramps or reduce the duty cycle.

n03: S_fault

What it means: S300/S700: the preset following error limit was exceeded. The output stage stays on.^[12]

Also on: S300 and S700 (not AKD)

Likely causes

• Axis cannot keep up with the commanded move
• Tight mechanics or gains not tuned

First checks, in this order

1. Check the mechanics.
2. Use flatter ramps or retune the loops before F03 trips the axis.