Siemens SINAMICS V90 Fault Codes

F7801: Motor overcurrent

What it means: The motor current went above the permissible motor limit current. The drive removes the pulses (OFF2) and the motor coasts to a stop.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Load too high or acceleration (up ramp) too short
• Effective current limit set too low
• Current controller not set correctly
• Motor braked with too high a static torque correction factor
• Short circuit or ground fault in the motor cable
• Motor current rating does not match the drive

First checks, in this order

1. Reduce the load or make the up ramp longer.
2. Check the motor and the motor power cable for a short circuit or ground fault.
3. Check that the motor and drive are a matching combination.
4. Reduce the static torque correction factor.

F30001: Power unit: Overcurrent

What it means: The power unit itself detected an overcurrent and tripped. F7801 is the motor current limit; F30001 is reported by the power stage.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Control loop or controller gains set wrong
• Short circuit or ground fault in the motor or power cable
• Power cables connected wrong or longer than allowed
• Line phase interrupted
• Defective power unit

First checks, in this order

1. Check the motor data and repeat commissioning if needed.
2. Adjust the speed loop gain p29120 and the position loop gain p29110.
3. Check the power cable connections, length, and look for a short circuit or ground fault.
4. Check the line supply phases and the external braking resistor connection.
5. Replace the power unit if the fault returns with good wiring and settings.

F30002: DC link voltage, overvoltage

What it means: The power unit measured too high a DC link voltage, typically from energy the motor feeds back while braking.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Motor regenerates too much energy when decelerating
• Supply voltage too high
• Line phase interrupted

First checks, in this order

1. Make the ramp-down (deceleration) time longer.
2. Activate the DC link voltage controller.
3. Use a braking resistor; fit an external one if the built-in resistor is not enough (see A52901).
4. Check the supply voltage and the line phases.

F30003: DC link voltage, undervoltage

What it means: The DC link voltage fell below the permissible level.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Line supply failure or interruption
• Line supply voltage below the permissible value
• Line phase interrupted

First checks, in this order

1. Measure the line supply voltage at the drive.
2. Check the line phases and the supply feeding the drive.
3. Check the line supply voltage setting (p29006).
4. Look for other supply messages in the fault buffer.

F30004: Drive heat sink overtemperature

What it means: The power unit heat sink is above its permissible temperature. Alarm A5000 comes first; this fault trips about 5 K higher.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Fan failure or poor cooling
• Overload
• Ambient temperature too high
• Pulse frequency too high

First checks, in this order

1. Check that the drive fan runs and the air path is clear.
2. Check the ambient temperature in the cabinet.
3. Check the motor load and duty cycle.
4. Reduce the pulse frequency if it is above the rated pulse frequency.

F30005: Power unit: Overload I2t

What it means: The power unit carried more than its rated current for too long (I2t overload).^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Rated power unit current exceeded for too long
• Load duty cycle not kept

First checks, in this order

1. Reduce the continuous load.
2. Adapt the load duty cycle.
3. Check the rated currents of the motor and the power unit.

F7011: Motor overtemperature

What it means: The motor is too hot. Alarm A7012 reports when the motor temperature model passes its alarm threshold.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Motor overloaded
• Ambient temperature around the motor too high
• Broken wire or sensor not connected
• Motor temperature model parameters set wrong

First checks, in this order

1. Reduce the motor load.
2. Check the ambient temperature and the motor ventilation.
3. Check the wiring and connections.
4. Check the motor temperature model parameters.

F7900: Motor blocked/speed controller at its limit

What it means: The motor sat at the torque limit below a low speed threshold for too long, so the drive treats it as blocked. V90 PTI: delay p2177 and speed threshold p2175. V90 PN manual: 1 s below 120 rpm. It can also come from an oscillating speed loop that keeps hitting its limit.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Motor or machine mechanically blocked
• Torque limit too low for the load
• Wrong actual value inversion or encoder pulse number
• Oscillating speed control driving the controller to its limit

First checks, in this order

1. Check that the motor shaft and the machine can turn freely.
2. Check the torque limit.
3. Check the actual value inversion, the motor encoder connection and the encoder pulse number.
4. V90 PTI: p29046 switches this protection on or off in speed control mode.

F7901: Motor overspeed

What it means: The actual motor speed went above the maximum permissible speed (or, on the V90 PTI, the set speed limit).^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Maximum speed p1082 set too low for the process
• Speed limit exceeded (V90 PTI: p29070, p29071 and DI signals SLIM1, SLIM2)
• Peaks or overshoot in the actual speed

First checks, in this order

1. Check and correct the maximum speed p1082.
2. V90 PTI: check the speed limits p29070 and p29071 and the SLIM1 and SLIM2 inputs.
3. Trace the actual speed for peaks; if a peak is very large, contact Siemens support.

F7410: Current controller output limited

What it means: The current controller output stayed at its limit for more than 16 ms while the actual current was zero, so the drive cannot drive current into the motor.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Motor not connected or motor contactor open
• DC link voltage missing
• Defective power unit (Motor Module)

First checks, in this order

1. Check the motor power cable and any contactor between drive and motor.
2. Check the DC link voltage.
3. Check the power unit.

F7412: Commutation angle incorrect (motor model)

What it means: The drive found a wrong commutation angle, which can make the speed controller unstable (positive feedback).^[1][2][3][4]

Drive response: ENCODER (encoder fault, leads to OFF2); acknowledgement IMMEDIATELY

Likely causes

• Encoder misaligned to the magnet position, for example after remounting
• Damaged motor encoder
• Wrong motor model data
• Pole position identification returned a wrong value
• Disturbed encoder speed signal
• Unstable control loop from wrong parameters

First checks, in this order

1. If the encoder was remounted, adjust it again.
2. Replace the motor encoder if it is defective.
3. Check stator resistance, cable resistance and leakage inductance against the motor data sheet.
4. With pole position identification active, deselect and select it to force a new identification.

F1611: SI CU: Defect detected

What it means: The built-in Safety Integrated function found an error and triggered Safe Torque Off (STO), so the motor coasts down. On the V90 this is the fault shown when the two STO inputs are at different levels.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• STO1 and STO2 inputs at different levels (one high, one low)
• STO input pulse shorter than 500 ms
• Wiring fault on the STO terminals
• Software or Control Unit fault

First checks, in this order

1. Check that STO1 and STO2 switch together: both high to run, both low to stop.
2. Make sure the high level of the input pulse lasts longer than 500 ms.
3. Switch the drive power off and on.
4. Update the firmware; replace the Control Unit if the fault keeps returning.

F7452: Following error too high

What it means: The gap between position setpoint and actual position (following error) is larger than the tolerance in p2546.^[1][2][3][4]

Drive response: OFF1; acknowledgement IMMEDIATELY

Likely causes

• Tolerance p2546 too small
• Position loop gain too low
• Torque or acceleration capacity exceeded
• Position measuring (encoder) fault
• Wrong position control direction
• Mechanics locked
• Traversing speed or setpoint jumps too high

First checks, in this order

1. Check p2546 against the real process.
2. Check the position loop gain.
3. Check that the machine is free and the motor has enough torque.
4. Check the encoder and the control direction.
5. Reduce the traversing speed or the setpoint steps.

F30021: Ground fault

What it means: The power unit detected a ground fault.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Ground fault in the power cables
• Winding fault or ground fault in the motor

First checks, in this order

1. Check the power cable connections.
2. Check the motor and its power cable for a ground fault.

F30011: Line phase failure in main circuit

What it means: The DC link voltage ripple at the power unit is above the permissible limit, which points to a missing or unbalanced phase.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Line phase failed
• Line phases badly unbalanced
• Blown fuse in one phase of the main circuit
• Motor phase failed

First checks, in this order

1. Check the main circuit fuses.
2. Check whether a single-phase load is distorting the line voltages.
3. Check the motor feeder cables.

F30015: Phase failure motor cable

What it means: The drive detected a lost phase in the motor cable. It can also appear with a correctly wired motor when unstable speed control makes the torque oscillate.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Broken or loose phase in the motor power cable
• Unstable speed control

First checks, in this order

1. Check the motor power cable and its connectors.
2. Check the speed controller settings.

F31110: Serial communications error

What it means: Data transfer between the motor encoder and the drive failed on the serial encoder protocol.^[1][2][3][4]

Drive response: ENCODER (encoder fault, leads to OFF2); acknowledgement PULSE INHIBIT

Likely causes

• Encoder cable fault or poor shield connection
• Defective encoder or encoder cable

First checks, in this order

1. Check the encoder cable and the shield connection.
2. Replace the encoder cable or the encoder.

F31111: Encoder 1: Absolute encoder internal error

What it means: The absolute encoder reports internal fault bits.^[1][2][3][4]

Drive response: ENCODER (encoder fault, leads to OFF2); acknowledgement PULSE INHIBIT

Likely causes

• Encoder cable loose or not routed EMC compliant
• Motor too hot
• Defective encoder

First checks, in this order

1. Check the encoder cable connection and its EMC compliant routing.
2. Check the motor temperature.
3. Replace the motor or encoder.

F31112: Error bit set in the serial protocol

What it means: The encoder sent an error bit in the serial protocol. Siemens points to the same checks as F31111.^[1][2][3][4]

Drive response: ENCODER (encoder fault, leads to OFF2); acknowledgement PULSE INHIBIT

Likely causes

• Encoder cable loose or not routed EMC compliant
• Motor too hot
• Defective encoder

First checks, in this order

1. Check the encoder cable connection and its EMC compliant routing.
2. Check the motor temperature.
3. Replace the motor or encoder.

F31150: Initialization error

What it means: The encoder function is not working correctly.^[1][2][3][4]

Drive response: ENCODER (encoder fault, leads to OFF2); acknowledgement PULSE INHIBIT

Likely causes

• Encoder type (incremental or absolute) does not suit the setup
• Encoder cable fault

First checks, in this order

1. Check the encoder type in use and the encoder cable.
2. Read any other faults in the buffer that give more detail.

F31117: Inversion error signals A/B/R

What it means: On a square-wave encoder, the inverted signals A*, B* and R* do not mirror A, B and R as they should.^[1][2][3][4]

Drive response: ENCODER (encoder fault, leads to OFF2); acknowledgement PULSE INHIBIT

Likely causes

• Encoder signal fault
• Cable or connection fault

First checks, in this order

1. Check the encoder, the cable and their connections.

F31130: Zero mark and position error from the coarse synchronization

What it means: After the pole position was set up, the encoder zero mark showed up outside the permissible range, so fine synchronization did not happen.^[1][2][3][4]

Drive response: ENCODER (encoder fault, leads to OFF2); acknowledgement PULSE INHIBIT

Likely causes

• Encoder cable not routed EMC compliant
• Loose plug connections
• Defective encoder or encoder cable

First checks, in this order

1. Check the EMC compliant routing of the encoder cable.
2. Check the plug connections.
3. Replace the encoder or the encoder cable.

F31131: Encoder 1: Deviation position incremental/absolute too large

What it means: The absolute position read from the encoder differs too much from the incremental position (limit 15 pulses, or 60 quadrants); on an incremental encoder the zero mark spacing is off.^[1][2][3][4]

Drive response: ENCODER (encoder fault, leads to OFF2); acknowledgement PULSE INHIBIT

Likely causes

• Interference on the encoder cable
• Loose plug connections
• Dirty code disk or strong magnetic fields near the motor
• Defective encoder or encoder cable

First checks, in this order

1. Check the EMC compliant routing of the encoder cable.
2. Check the plug connections.
3. Check for a dirty code disk or strong magnetic fields.
4. Replace the encoder or the encoder cable.

F52904: Control mode change

What it means: The control mode was changed (on the V90 PTI with p29003). The drive must save the parameters and restart before the new mode works.^[1][2][3][4]

Drive response: OFF2; acknowledgement POWER ON

Likely causes

• Control mode parameter changed

First checks, in this order

1. Save the parameters (RAM to ROM) on the BOP or in SINAMICS V-ASSISTANT.
2. Switch the drive power off and on.

F52980: Absolute encoder motor changed

What it means: A motor with absolute encoder was swapped: the motor ID read now differs from the commissioned motor ID.^[1][2][3][4]

Drive response: OFF1; acknowledgement IMMEDIATELY

Likely causes

• Motor replaced with a different type

First checks, in this order

1. Acknowledge the fault, then save the newly commissioned parameters to the drive ROM; the drive then configures the new motor automatically.

F52981: Absolute encoder motor mismatched

What it means: The connected absolute encoder motor cannot run on this drive because the drive does not support its motor ID.^[1][2][3][4]

Drive response: OFF1; acknowledgement IMMEDIATELY

Likely causes

• Motor and drive combination not supported

First checks, in this order

1. Use an absolute encoder motor that suits this drive.

F52983: No encoder detected

What it means: The drive cannot find an encoder, and the V90 does not support encoderless operation.^[1][2][3][4]

Drive response: OFF1; acknowledgement IMMEDIATELY

Likely causes

• Encoder cable unplugged or damaged
• Motor without encoder connected

First checks, in this order

1. Check the encoder cable between drive and motor.
2. Use a servo motor with an encoder.

F52984: Incremental encoder motor not configured

What it means: An incremental encoder motor is connected, but its commissioning failed because the drive does not know the motor ID.^[1][2][3][4]

Drive response: OFF1; acknowledgement IMMEDIATELY

Likely causes

• Motor ID not set for an incremental encoder motor

First checks, in this order

1. Set the motor ID in parameter p29000.

F52985: Absolute encoder motor wrong

What it means: The absolute encoder motor ID is not usable: it was stored wrong at the factory or the drive firmware does not know it.^[1][2][3][4]

Drive response: OFF1; acknowledgement IMMEDIATELY

Likely causes

• Motor ID written wrong during manufacture
• Drive firmware does not support the motor ID

First checks, in this order

1. Update the drive firmware.
2. Use a correct absolute encoder motor.

F7995: Motor identification failure

What it means: With an incremental encoder motor, the drive identifies the pole position at the first servo on. If the motor is already turning, for example pushed by the load, the identification can fail.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Motor shaft moving at servo on, driven by an external force

First checks, in this order

1. Bring the motor to a standstill before servo on.
2. Check that the load does not turn the shaft at servo on.

F30027: Precharging DC link time monitoring

What it means: The DC link could not be precharged in the expected time after power on.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Line supply voltage missing or too low
• Line contactor or line side switch not closed
• Precharge resistors overheated, for example from too many power ons in a short time
• Ground fault or short circuit in the DC link
• Defective precharge circuit

First checks, in this order

1. Check the line supply voltage at the input terminals.
2. Check the line contactor or switch.
3. Avoid frequent power cycling so the precharge resistors can cool.

F30036: Internal overtemperature

What it means: The temperature inside the drive is above its permissible limit. It can only be acknowledged once it has cooled 5 K below that limit.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Fan failure or poor cooling
• Overload
• Ambient temperature too high

First checks, in this order

1. Check that the fan runs.
2. Check the fan elements.
3. Check that the ambient temperature is in the permissible range.

F30050: 24 V supply overvoltage

What it means: The voltage monitor reports an overvoltage on the 24 V supply of the drive.^[1][2][3][4]

Drive response: OFF2; acknowledgement POWER ON

Likely causes

• 24 V supply voltage too high

First checks, in this order

1. Check the 24 V power supply.
2. Replace the module if needed.

F7802: Infeed or power unit not ready

What it means: After the internal power on command, the power unit did not report ready.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• DC link voltage missing
• Monitoring time too short
• Defective power unit

First checks, in this order

1. Check that the line supply is on and the DC link is charged.
2. Replace the drive if the power unit is defective.

F7800: Drive: No power unit present

What it means: The drive cannot read the power unit parameters, or none are stored in the power unit.^[1][2][3][4]

Drive response: NONE; acknowledgement IMMEDIATELY

Likely causes

• Power unit data unreadable or missing

First checks, in this order

1. Switch the drive power off and on.
2. Replace the module.

F7403: Lower DC link voltage threshold reached

What it means: DC link voltage monitoring is active and the DC link voltage reached the lower threshold while running.^[1][2][3][4]

Drive response: OFF1; acknowledgement IMMEDIATELY

Likely causes

• Line supply voltage too low or dipping
• Lower threshold set too high

First checks, in this order

1. Check the line supply voltage.
2. Check the infeed.
3. Lower the threshold, or switch off the DC link voltage monitoring if that suits the machine.

F7404: Upper DC link voltage threshold reached

What it means: DC link voltage monitoring is active and the DC link voltage reached the upper threshold while running.^[1][2][3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Line supply voltage too high
• Braking energy not taken away fast enough

First checks, in this order

1. Check the line supply voltage.
2. Check the infeed and the brake module or braking resistor.
3. Raise the threshold, or switch off the DC link voltage monitoring if that suits the machine.

F1910: Fieldbus: setpoint timeout

What it means: Setpoints from the fieldbus interface (Modbus or USS) stopped arriving.^[1][2][3][4]

Also on: Listed in both manuals with the Modbus/USS wording; on the V90 PN, loss of PROFINET setpoints is reported as F8501.

Drive response: OFF3; acknowledgement IMMEDIATELY

Likely causes

• Bus connection interrupted
• Controller switched off
• Controller set to STOP

First checks, in this order

1. Restore the bus connection (RS485 cable and connectors).
2. Set the controller (PLC) to RUN.

F8501: PROFIdrive: Setpoint timeout

What it means: Setpoints from PROFINET stopped arriving.^[3][4]

Drive response: OFF3; acknowledgement IMMEDIATELY

Likely causes

• PROFINET connection interrupted
• Controller switched off or set to STOP
• PROFINET defective

First checks, in this order

1. Restore the PROFINET connection (cable and connectors).
2. Set the controller to RUN.

F1911: PROFIdrive: Clock cycle synchronous operation clock cycle failure

What it means: The global control telegram that keeps isochronous (clock synchronous) PROFINET operation in step failed for several bus cycles or broke the time grid.^[3][4]

Drive response: OFF1; acknowledgement IMMEDIATELY

Likely causes

• Bus wiring problem (cable, connector, shielding)
• Short or permanent communication interruption
• Bus or controller overloaded, for example bus cycle time too short

First checks, in this order

1. Check the physical bus: cable, connectors, shielding.
2. Check whether communication was briefly or permanently interrupted.
3. Check the bus and controller load (cycle time).

F7220: Drive: Master control by PLC missing

What it means: The "master control by PLC" signal dropped out while running.^[1][2][3][4]

Drive response: OFF1; acknowledgement IMMEDIATELY

Likely causes

• Wrong input assigned for master control by PLC
• Higher level controller withdrew the signal
• Fieldbus data transfer interrupted

First checks, in this order

1. Check the input for master control by PLC.
2. Check that the controller sends the signal, and switch it in if needed.
3. Check the fieldbus data transfer between master and drive.

F7450: Standstill monitoring has responded

What it means: After the standstill monitoring time ran out, the axis moved out of the standstill window.^[1][2][3][4]

Drive response: OFF1; acknowledgement IMMEDIATELY

Likely causes

• Position loop gain too low
• Position loop gain too high (oscillation)
• Mechanical overload
• Motor cable wrong (phase missing or swapped)

First checks, in this order

1. Check the position loop gain.
2. Check the mechanics for overload.
3. Check the motor power cable phases.

F7451: Position monitoring has responded

What it means: When the position monitoring time p2545 ran out, the axis still had not reached the positioning window p2544.^[1][2][3][4]

Drive response: OFF1; acknowledgement IMMEDIATELY

Likely causes

• Positioning window p2544 too small
• Monitoring time p2545 too short
• Position loop gain too low or too high
• Axis mechanically locked

First checks, in this order

1. Check p2544 and p2545.
2. Check the position loop gain.
3. Check that the axis can move freely.

F7491: STOP cam minus reached

What it means: The axis reached the STOP cam minus. If this happens while moving in the positive direction, the STOP cam wiring is wrong.^[1][2][3][4]

Drive response: OFF3; acknowledgement IMMEDIATELY

Likely causes

• Axis traveled onto the minus STOP cam
• STOP cam wired wrong

First checks, in this order

1. Move the axis off the cam in the positive direction, back into the valid range.
2. Check the wiring of the STOP cam.

F7492: STOP cam plus reached

What it means: The axis reached the STOP cam plus. If this happens while moving in the negative direction, the STOP cam wiring is wrong.^[1][2][3][4]

Drive response: OFF3; acknowledgement IMMEDIATELY

Likely causes

• Axis traveled onto the plus STOP cam
• STOP cam wired wrong

First checks, in this order

1. Move the axis off the cam in the negative direction, back into the valid range.
2. Check the wiring of the STOP cam.

F7481: EPOS: Axis position < software limit switch minus

What it means: The actual axis position is below the software limit switch minus.^[1][2][3][4]

Drive response: OFF1 (OFF2, OFF3); acknowledgement IMMEDIATELY

Likely causes

• Target position beyond the minus software limit
• Software limit switch minus set wrong

First checks, in this order

1. Correct the target position.
2. Check the software limit switch minus (p2580).

F7482: EPOS: Axis position > software limit switch plus

What it means: The actual axis position is above the software limit switch plus.^[1][2][3][4]

Drive response: OFF1 (OFF2, OFF3); acknowledgement IMMEDIATELY

Likely causes

• Target position beyond the plus software limit
• Software limit switch plus set wrong

First checks, in this order

1. Correct the target position.
2. Check the software limit switch plus (p2581).

F52931: Gear box limit

What it means: The electronic gear ratio p29012[x] / p29013[x] is outside the allowed range of 0.02 to 200.^[1][2]

Drive response: OFF1; acknowledgement IMMEDIATELY

Likely causes

• Electronic gear ratio set out of range

First checks, in this order

1. Set p29012 and p29013 so the ratio is between 0.02 and 200.

F52911: Positive torque limitation value error

What it means: One of the positive torque limit values (p29050, p1520) has become less than 0.^[1][2]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Positive torque limit set below 0

First checks, in this order

1. Set p29050 and p1520 to 0 or higher.

F52912: Negative torque limitation value error

What it means: One of the negative torque limit values (p29051, p1521) has become greater than 0.^[1][2]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Negative torque limit set above 0

First checks, in this order

1. Set p29051 and p1521 to 0 or lower.

F7090: Drive: Upper torque limit less than the lower torque limit

What it means: The upper torque limit p29050 is set lower than the lower torque limit p29051.^[3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Torque limits entered the wrong way round

First checks, in this order

1. Set p29050 at least as high as p29051.

F7575: Drive: Motor encoder not ready

What it means: The motor encoder reports that it is not ready.^[3][4]

Drive response: OFF2; acknowledgement IMMEDIATELY

Likely causes

• Motor encoder initialization failed
• Parking encoder function active (encoder control word G1_STW.14 = 1)

First checks, in this order

1. Read the other encoder faults in the fault buffer.
2. Check bit G1_STW.14 in the encoder control word from the PLC.

F1018: Booting has been interrupted several times

What it means: Start-up was interrupted several times, so the drive booted with factory settings.^[1][2][3][4]

Drive response: NONE; acknowledgement POWER ON

Likely causes

• Power supply interrupted during boot
• CPU crashed
• Invalid parameter set

First checks, in this order

1. Switch the power off and on; the drive reboots from valid parameters if they exist.
2. Restore a valid parameter set, for example a backup from the micro SD/SD card, save, then power cycle.
3. Or carry out a first commissioning, save, then power cycle.

F1000: Internal software error

What it means: An internal software error occurred in the drive.^[1][2][3][4]

Drive response: OFF2; acknowledgement POWER ON

Likely causes

• Internal firmware error

First checks, in this order

1. Read the fault buffer.
2. Switch all components off and on.
3. Update the firmware.
4. Contact Siemens support or replace the Control Unit if it repeats.

A5000: Drive heat sink overtemperature

What it means: The inverter heat sink has reached its alarm temperature. If it rises another 5 K, fault F30004 trips.^[1][2][3][4]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• Ambient temperature too high
• Load or duty cycle too heavy for the drive
• Cooling failure
• Built-in braking resistor heating the heat sink

First checks, in this order

1. Check that the ambient temperature is within limits.
2. Check the load and duty cycle sizing.
3. Check the cooling (fan and air path).
4. If A52901 shows at the same time, switch from the built-in to an external braking resistor.

A7012: Motor temperature model 1/3 overtemperature

What it means: The motor temperature model shows the motor has passed its alarm threshold.^[1][2][3][4]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• Motor load too high
• Ambient temperature around the motor too high

First checks, in this order

1. Check the motor load and reduce it if needed.
2. Check the temperature around the motor.

A7805: Power unit overload I2t

What it means: The power unit has passed its I2t overload alarm threshold.^[1][2][3][4]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• Continuous load too high
• Duty cycle too heavy
• Motor and drive rated currents not matched

First checks, in this order

1. Reduce the continuous load.
2. Adapt the load duty cycle.
3. Check the rated currents assigned to the motor and the drive.

A30016: Load supply switched off

What it means: The DC link voltage is too low, which the drive reports as its load (main) supply being off.^[1][2][3][4]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• Main power supply switched off or missing

First checks, in this order

1. Switch on the load (main) supply.
2. Check the line supply if needed.

A30031: Hardware current limiting in phase U

What it means: The hardware current limit responded and blocked the pulses in that phase for one pulse period. Siemens shows A30031 whenever phase U, V or W hits the hardware limit.^[1][2][3][4]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• Control parameters set wrong
• Fault in the motor or the power cables
• Power cables longer than allowed
• Motor load too high
• Defective power unit

First checks, in this order

1. Check the motor data, or run a motor data identification.
2. Check the motor load.
3. Check the power cable connections, length, and look for a short circuit or ground fault.

A52901: Braking resistor reaches alarm threshold

What it means: The braking resistor's heat capacity has reached the alarm threshold set in p29005.^[1][2][3][4]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• Too much braking energy for the resistor
• Deceleration too fast

First checks, in this order

1. Increase the deceleration time.
2. Change to an external braking resistor (terminals DCP, R1).
3. If A5000 shows at the same time, switch from the built-in to an external braking resistor.

A52902: Quick stop (EMGS) missing

What it means: Servo on was requested while the EMGS (quick stop) digital input was off.^[1][2][3][4]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• EMGS input off, for example emergency stop circuit open

First checks, in this order

1. Switch on the EMGS digital input, then give servo on again.

A30042: Power unit: Fan has reached the maximum operating hours

What it means: The drive fan is within 500 hours of, or past, its fixed life of 40,000 operating hours.^[1][2][3]

Also on: V90 PN: listed from the 08/2023 manual edition.

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• Fan operating time near or past its limit

First checks, in this order

1. Replace the fan.
2. Reset the operating hours counter p0251.
3. Fault value r0949 bit 0 means 500 hours left, bit 1 means the limit is passed.

A6310: Supply voltage (p29006) incorrectly parameterized

What it means: After precharging, the measured DC voltage does not fit the supply voltage set in p29006 (allowed: 1.16 x p29006 < r0026 < 1.6 x p29006).^[1][2][3][4]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• p29006 does not match the real supply voltage
• Line supply voltage out of range

First checks, in this order

1. Check p29006 against the real supply voltage and correct it.
2. Measure the line supply voltage.

A7496: SON enable missing

What it means: A servo on (SON) command is needed but missing.^[1][2]

Also on: On the V90 PN the same number is named "EPOS: Enable not possible".

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• IPos mode with p29008 = 1: no servo on command sent over Modbus
• IPos mode: rising edge on P-TRG while the drive is servo off
• PTI mode: a fault caused by "Enable trial run" in SINAMICS V-ASSISTANT

First checks, in this order

1. Send the servo on command to the drive over Modbus.
2. Put the drive in servo on first, then give the P-TRG rising edge.
3. Acknowledge the faults and run "Enable trial run" again.

A7496: EPOS: Enable not possible

What it means: In EPOS control mode, the drive has not received a servo on command over PROFINET.^[3][4]

Also on: On the V90 PTI the same number is named "SON enable missing".

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• PLC not sending servo on over PROFINET

First checks, in this order

1. Send the servo on command to the drive over PROFINET.

A8526: PROFIdrive: No cyclic connection

What it means: The drive has no cyclic PROFINET connection to the controller.^[3][4]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• PLC not in cyclic operation
• Station name or IP address of the drive does not match the PLC project

First checks, in this order

1. Establish the cyclic connection and put the controller into cyclic operation.
2. Check the drive's "Name of Station" and "IP of Station" (r8930, r8931).

A31411: Encoder 1: Absolute encoder signals internal alarms

What it means: The absolute encoder reports internal alarm bits.^[1][2][3][4]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• Encoder cable loose or not routed EMC compliant
• Motor too hot
• Encoder wearing out or defective

First checks, in this order

1. Check the encoder cable connection and its EMC compliant routing.
2. Check the motor temperature.
3. Replace the motor or encoder.

A31412: Error bit set in the serial protocol

What it means: The encoder sent an error bit in the serial protocol (alarm level).^[1][2][3][4]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• Interference on the encoder cable
• Loose plug connections
• Defective encoder

First checks, in this order

1. Switch all components off and on.
2. Check the EMC compliant routing of the cables.
3. Check the plug connections.
4. Replace the encoder.

A1045: Configuring data invalid

What it means: Some saved parameter values could not be loaded because the parameter files in non-volatile memory contain errors.^[1][2][3][4]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• Parameter files in non-volatile memory corrupted

First checks, in this order

1. Save again with "Copy RAM to ROM" in SINAMICS V-ASSISTANT or on the BOP; this overwrites the bad files and the alarm clears.

A52900: Failure during data copying

What it means: Copying parameters between the drive and the micro SD/SD card did not finish.^[1][2][3][4]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• Copying halted
• Micro SD/SD card removed
• Drive not in the stop state

First checks, in this order

1. Plug the micro SD/SD card back in.
2. Make sure the drive is in the stop state, then copy again.

A7461: EPOS: Reference point not set

What it means: A traversing block or direct setpoint was started, but the axis has no reference point.^[1][2][3][4]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• Axis not referenced

First checks, in this order

1. Reference the axis: search for reference, flying referencing, or set the reference point.

A7092: Drive: Moment of inertia estimator still not ready

What it means: The moment of inertia estimator has not found valid values yet (load inertia ratio p29022), so acceleration cannot be calculated.^[1][2][3][4]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• Axis not moved enough for the estimator to settle

First checks, in this order

1. Move the axis until the estimator stabilizes; the alarm then clears by itself.

A7585: P-TRG or CLR active

What it means: In PTI mode, or a compound mode with PTI, the P-TRG or CLR function is active.^[1][2]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• P-TRG or CLR input function active in PTI mode

First checks, in this order

1. In PTI mode, deactivate the P-TRG or CLR function.
2. In a compound mode with PTI, do not switch to the other mode.

A52932: PTO max limit

What it means: The pulse train output (PTO) frequency is above its limit: 280 kHz with an incremental encoder motor, 120 kHz with an absolute encoder motor.^[1][2]

Drive response: NONE (alarm: drive keeps running, clears itself once the cause is gone)

Likely causes

• PTO ratio gives too high an output frequency at the running speed

First checks, in this order

1. Change the PTO ratio (p29031, p29032) to lower the output frequency.