Digitax SF Drive Fault Codes (2026)

Digitax SF Drive Fault Codes (2026) – Comprehensive 2026 troubleshooting guide for the Nidec Control Techniques Digitax SF servo drive. Learn to interpret numeric alarm codes, use Digitax SF Connect software, and resolve hardware and software trips.

The Nidec Control Techniques Digitax SF is a compact, cost-effective servo solution designed for low-power precision applications ranging from 50W to 2kW. Equipped with high-resolution magnetic encoder technology, it is a popular choice for semiconductor manufacturing, packaging, and textile machinery. When the drive identifies an operational issue, it halts the motor and displays a numeric alarm code on its integrated 7-segment LED display (e.g., AL.07 for Overload).

This 2026 guide provides the diagnostic framework to help you decode these numeric alarms, utilize the dedicated setup software, and resolve trips to maintain your high-precision motion systems.

Digitax SF Fault Codes Reference Table

Below is the reference list of alarms for the Digitax SF. Because this drive utilizes numeric indicators, please locate the specific alarm number appearing on your drive’s front panel to find the corresponding cause and remedy.

Fault Code and Meaning	Cause and Remedy
900 Encoder overheat detection	Cause: The temperature inside the absolute encoder has exceeded the temperature value specified by Encoder: Overheat detection – Value (267.0). An alarm can be output in place of the warning. Remedy: Reduce the ambient temperature and improve thermal radiation conditions. Check the setting of Encoder: Overheat detection – Value (267.0). Reset Method: After eliminating the cause, then input RESET signal to the RESET terminal on the connector CN1.
901 Encoder battery voltage drop error detection	Cause: The battery voltage of the absolute encoder has dropped below the voltage set by Encoder: Battery voltage drop detection – Value (268.0). Remedy: Replace the battery in the absolute encoder. Check the Encoder: Battery voltage drop detection – Value (268.0). Reset Method: After eliminating the cause, then input RESET signal to the RESET terminal on the connector CN1.
902 Emergency stop	Cause: The E-STOP control terminal digital input is open. Remedy: Close the E-STOP control terminal digital input. Check for proper I/O connections. Reset Method: After eliminating the cause, then input RESET signal to the RESET terminal on the connector CN1.
903 Encoder communication warning	Cause: Failed to obtain ABS encoder temperature and battery voltage data. Remedy: Check for wire disconnection or loose connection of pins. Keep the cable length no longer than 20 m. Check for noise interference: Use a shielded twist-pair cable. Keep the encoder cable away from the motor power cable. Connect Ground/Earth FG firmly. Use ferrite core for the motor power cable and encoder cable. If any of the above didn’t resolve the issue, please contact the supplier. Reset Method: After eliminating the cause, then input RESET signal to the RESET terminal on the connector CN1.
904 Excessive position error	Cause: The position error consecutively exceeded the setting of Position error warning detection: Value (363.0) and the setting of Position error warning detection: Delay time (365.0). Remedy: Adjust the tuning parameters. Check the command from the host controller. Check the wiring. Verify that the brake is released. Verify that the motor is not in a torque limit state per torque command limit. Check the settings of Position error warning detection: Value (363.0) and Position error warning detection: Delay time (365.0). Reset Method: After eliminating the cause, then input RESET signal to the RESET terminal on the connector CN1.
Alarm No. 0 System	Cause: Error in the control circuit. The control circuit CPU is not operating normally. Remedy: Please contact the supplier of the drive.
Alarm No. 1 EEPROM data	Cause: Error during writing of Parameters. Remedy: Check the interface cable and re-write the parameters.
Alarm No. 2 Product code	Cause: Unable to read the product code. The drive-motor pairing was wrong. The encoder cable was not connected to the drive correctly (includes wiring disconnection). Remedy: Check the motor-drive pairing. Check the encoder cable connections.
Alarm No. 4 Overspeed	Cause: The motor rotational speed exceeded the rated maximum rotational speed. The command from the host controller was not appropriate. There were residual pulses due to drive limit switch input or other reasons. Remedy: Adjust the Tuning parameters. Check the command. Verify that the location of the limit sensor hasn’t shifted.
Alarm No. 5 Speed	Cause: Position control/Speed control error. The command was not appropriate. The load was too heavy and could not keep up with the command speed. Speed error detection: Value (90.0) was not appropriate. Remedy: Check the command from the host controller. Adjust the tuning parameters. Check the setting of Speed error detection: Value (90.0). Verify that the brake is released. Verify that the motor is not in a torque limit state per torque command limit.
Alarm No. 6 Position	Cause: Position Control Error. The acceleration time was too short. There was wrong connection or disconnection of the motor power cable or encoder cable. Position error detection: Value (87.0) was not appropriate. Remedy: Adjust the tuning parameters. Check the command from the host controller. Check the wiring. Check the setting of Position error detection: Value (87.0). Verify that the brake is disengaged. Verify that the motor is not in a torque limit state per torque command limit.
Alarm No. 7 Overload	Cause: Immediately after operation started: Motor did not move or moved slightly. During operation: Alarm occurred at same point of motion profile. Acceleration time too short. Motor was not accelerating (machine collided with object). Motor capacity too small (load too large). Significant vibration or noise generated. Tuning parameters or commands not appropriate. Remedy: Executing overloaded motion continuously may burnout the motor. Check motor power cable connections. Verify user-selected motor capacity is appropriate. Verify brake is disengaged. Verify deceleration ratio is appropriate. Check acceleration time, torque waveform, and load ratio. Verify no obstacles inside work area. Increase motor capacity or install a decelerator. Adjust Tuning parameters. Configure moderate commands (e.g., use command smoothing filter). Configure countermeasures for noise (notch filter or low-pass filter).
Alarm No. 8 Command overspeed	Cause: The position control input exceeded the max rotational speed. The command from the host controller was not appropriate. Remedy: Check the Pulse train command: Ratio (34.0 and 36.0). Check the commands from the host controller.
Alarm No. 9 Encoder pulse – Output frequency error	Cause: The frequency of the encoder pulse output exceeded 4 Mpps. Remedy: Check the numerator and denominator settings in the Encoder pulse output: Pulse ratio (276.0 and 278.0). Check the settings of Encoder pulse output: Error detection – Frequency upper limit (285.0) and Delay time (286.0).
Alarm No. 10 Positioning command overflow /Homing failure	Cause: External position command exceeded the absolute value range of ±1,073,741,823. The shift amount per one of the commands exceeded the ±2,147,483,647 range. Homing failed and timed out. Remedy: Select a value different from the current setting of Internal Position: Overflow detection (643.0). Adjust the parameters such that the shift amount will be within the ±1,073,741,823 range. Adjust the shift amount of Positioner motion, inching and test each one. Adjust the Homing related parameters.
Alarm No. 11 Encoder (multi-turn counter overflow)	Cause: Multi-turn data of the encoder has exceeded the ±32,767 range. Remedy: Check the setting of Absolute system (257.0). Verify that the multi-turn motion amount is within the ±32,767 range.
Alarm No. 12 Overheat	Cause: The control circuit temperature has exceeded the upper limit. Remedy: Check the drive’s installation method and environment. Lower the ambient temperature to below the rating.
Alarm No. 14 Overvoltage	Cause: The power supply to the control components has exceeded the drive circuit limits. Remedy: If during deceleration: Check regeneration status. Install a braking resistor if necessary. Use a command filter and gradually decrease speed. If regardless of deceleration: Verify AC Supply is within specification. Check for voltage changes during system operation.
Alarm No. 15 Power supply (AC Supply)	Cause: AC Supply voltage abnormally high, low, or not present. AC Supply not within input range. Power supply fluctuated significantly. SVON signal input without AC supply. Regeneration ON status too long. Remedy: Verify AC Supply connection and timing with SVON signal. Check for voltage fluctuations during operation. Provide stable power supply. If during deceleration: Check for regenerative voltage warnings. Install braking resistor if needed. Use command smoothing filter.
Alarm No. 16 Encoder (received data)	Cause: Encoder data changed rapidly for a short period of time. Remedy: Check for wire disconnection or loose connection of pins. Keep the cable length no longer than 20 m. Check for noise interference (Use shielded twist-pair cable). Keep encoder cable away from motor power cable. Connect Ground/Earth FG firmly. Use ferrite core for motor power cable and encoder cable. If unresolved, contact supplier.
Alarm No. 17 Encoder (no response)	Cause: Encoder communications were disconnected. Remedy: See remedy for Alarm No. 16 (Check wiring, noise, grounding, cable length).
Alarm No. 18 Encoder (circuit)	Cause: Battery voltage dropped or battery disconnected (Alarm No. 21 output in this case). Encoder temperature exceeded specification. Anomaly of the encoder itself detected. Remedy: If using absolute system: Replace the battery, connect it, and initialize the encoder. If not using absolute system: Check whether encoder temperature is within specification. If unresolved, contact supplier.
Alarm No. 19 Encoder (communication)	Cause: The initial communication with the encoder failed. Remedy: See remedy for Alarm No. 16 (Check wiring, noise, grounding, cable length).
Alarm No. 20 Encoder (multi-turn data)	Cause: Absolute encoder data changed rapidly. At startup, failed to receive multi-turn data internally. Remedy: See remedy for Alarm No. 16 (Check wiring, noise, grounding, cable length).
Alarm No. 21 Encoder (voltage drop)	Cause: The battery voltage dropped or became disconnected. It was the first start-up after battery connection. Remedy: Check for low battery voltage. Check for loose battery cable. Initialize the encoder.
Alarm No. 22 Voltage (control power)	Cause: The control power supply dropped. Remedy: Check the control power supply. Check for insufficient control power supply capacity. Check the wiring of user I/O connector 24 V (Pin 1 and Pin 2).
Alarm No. 23 Switch circuit	Cause: Control circuit has failed. Remedy: Please contact the supplier of the drive.
Alarm No. 24 Overcurrent	Cause: Anomaly of motor control current inside of the drive has been detected. Remedy: Check motor power cable (Grounding fault, wiring mistake). Check Tuning parameters and motor motion patterns (Increase acceleration/deceleration time). Enable/Disable Position command filter 1 and 4. Allow motor motion by disengaging brake/stopper. Check encoder cable (Connection, twist-pair). If unresolved, contact supplier.
Alarm No. 25 Inverter 1	Cause: Anomaly in the control circuit has been detected. Remedy: Check the motor power cable. Check for Grounding fault. Check for wiring mistake in motor power cable connections. If unresolved, contact supplier.
Alarm No. 26 Inverter 2	Cause: Anomaly in the control circuit has been detected. SERVO ON timed out. Remedy: Check the motor power cable. Check for Grounding fault. Check for wiring mistake in motor power cable connections. If unresolved, contact supplier.
Alarm No. 27 Current sensor	Cause: The ambient temperature of the current sensor was high. Anomaly of the current sensor has been detected. Remedy: Check the installation method and environment. If unresolved, contact supplier.
Alarm No. 28 Encoder (overheat)	Cause: The encoder PCB temperature has reached the upper limit. Remedy: Check the installation method and environment of the motor. Decrease the ambient temperature of the motor below the specification.
Alarm No. 29 Voltage drop (inside the drive)	Cause: The control power voltage (5 VDC) inside the drive has dropped. Remedy: Verify that there is no short-circuit in encoder cable connections. If the above didn’t resolve the issue, please contact the supplier of the drive.

Diagnostic Tip: The Digitax SF distinguishes between hardware-level protective functions (like Overcurrent and Encoder Errors) and software-level protections (like Overspeed and Position Error Too High).

How to Read Digitax SF Alarms via Digitax SF Connect

In 2026, the most effective way to troubleshoot the Digitax SF is through the Digitax SF Connect PC software. While the 7-segment display provides the code, the software provides the graphical context needed for complex tuning and diagnostics.

Alarm Time Stamping: The Digitax SF maintains an alarm log that stores the last 10 events. Using the setup software, you can view these alarms with precise timestamps to correlate them with machine events.
FFT Frequency Analysis: If you are experiencing vibration-related trips or resonance, Digitax SF Connect includes FFT analysis tools to help you configure notch filters and dampen mechanical oscillations.
Test Run & Positioning Table: You can use the software to perform test runs and view the real-time position error, which is essential for diagnosing Position Error Too High alarms.
Status Monitoring: Monitor torque commands, speed feedback, and I/O status in real-time to identify if an external sensor or mechanical jam is triggering a drive alarm.

Frequently Asked Questions (FAQ)

Q: What is the difference between an Alarm and a Status code on the Digitax SF?

A: An Alarm (indicated by “AL.” followed by a number) is a protective shutdown that stops the motor. A Status code (like “bb” for Base Block or “run”) indicates the current operating state of the drive and does not necessarily mean a fault has occurred.

Q: How do I reset a Digitax SF alarm?

A: Once the root cause of the fault has been cleared, you can reset the drive via:

Applying a signal to the Alarm Reset (A-RST) control input terminal.
Using the “Alarm Reset” function within the Digitax SF Connect software.
Cycling the Main Power (Wait until the display turns off completely before reapplying power).

Q: What does “AL.07” mean?

A: AL.07 indicates an Overload. This means the motor has been operating above its rated torque for too long. Check for mechanical jams, excessive friction in the drivetrain, or if the acceleration/deceleration ramps are too aggressive for the load inertia.

Q: Where is the fault history stored?

A: The fault history is stored in the drive’s non-volatile EEPROM. You can access the last 10 alarms through the “Alarm Log” menu on the front panel or via the diagnostic tab in the setup software.

Q: My drive shows an Encoder Error, what should I check?

A: First, ensure the encoder cable is securely connected at both the drive and motor ends. Since Digitax SF uses magnetic encoder technology, it is robust, but cable damage or high electrical noise (EMI) can still disrupt the 17-bit signal. Ensure the motor frame is properly grounded.