BECKHOFF EL70x7 Stepper Terminal Maintenance Guide

BECKHOFF EL70x7 Stepper Motor Terminal: Complete Guide to On site Hardware Diagnosis and Maintenance

In the field of industrial automation, Beckhoff's EL70x7 series EtherCAT stepper motor terminals (including EL7037 and EL7047) have become the preferred choice for small to medium-sized stepper motor drive applications due to their compact size, vector control technology, and up to 64 times micro step resolution. Whether it's the 24V/1.5A EL7037 or the 48V/5A EL7047, they both integrate limit switch inputs, encoder interfaces, and configurable digital input-output, enabling precise position and speed control.

However, on-site engineers may encounter issues such as terminals not being able to enter the OP state, motors not turning, overheating alarms, or communication interruptions during debugging and operation. This document aims to provide a comprehensive hardware diagnosis and troubleshooting guide for EL70x7 series terminals, based entirely on official technical documents, focusing on practical operational scenarios, covering the entire process from LED status interpretation, CoE parameter configuration to operation mode selection and firmware updates.

Key points for hardware installation and electrical connection

Proper hardware installation is the foundation for reliable operation. The connection of EL70x7 terminal is divided into four parts: power supply, motor winding, encoder, and digital I/O.

1.1 Connection between power supply and motor winding

System power supply: The terminal obtains logic power supply through E-bus (typical values EL7037 is 100mA, EL7047 is 140mA). The load voltage (motor power supply) must be connected through the power contact at the top of the terminal: EL7037 is 24V DC (-15%/+20%), and EL7047 is 8-48V DC.

Fuse protection: The electrical protection of the load voltage must limit the maximum current to 3 times the rated current (for a maximum of 1 second) to prevent damage to the output stage.

Winding wiring: Both ends of the same motor winding must be connected to the terminal points of the same output driver. For example, one winding is connected to A1 and A2, and the other winding is connected to B1 and B2. It is strictly prohibited to cross connect the two ends of one winding to different drivers (such as A1 and B1), otherwise the output stage will be immediately burned.

1.2 Encoder and limit switch connection

EL7037 and EL7047 both provide incremental encoder inputs (phases A, B, C) and two digital inputs (configurable limit switches or PLC cam switches). The encoder power supply (+24V and 0V) is taken from the power contact, and the maximum load capacity should refer to the specifications of the power terminal.

Encoder C-phase latch: The Enable latch C bit in the control word can be used to latch the current counter value on the rising edge of the C-phase.

External latch input: The latch can be triggered on the rising or falling edge through the Latch input terminal.

Digital input function: Input 1 and Input 2 can be configured as regular inputs, hardware enabled, or PLC cam switches (via object 0x8012:32/36).

1.3 Installation position and heat dissipation

Standard installation position: DIN rail horizontal installation, terminal connection facing forward. The ventilation openings are located at the upper and lower ends, utilizing natural convection to dissipate heat. A gap of at least 30mm should be maintained between the top and bottom.

Using fan module (ZB8610): The rated current of EL7037 can be increased from 1.5A to 3.0A, and EL7047 can be increased from 5A to 6.5A, but ZB8610 fan module must be used for forced ventilation and other installation positions (such as horizontal) are allowed.

Passive terminal placement: For passive EtherCAT terminals (such as EL9195) that do not participate in data exchange, no more than two should be connected in series continuously, otherwise it will affect the quality of the E-bus signal.

LED status indicator and diagnosis

The front panel of EL7047 (similar to EL7037) provides abundant LED indicator lights, which can preliminarily determine the terminal status without software.

2.1 System Status LED (Left Prism)

Meaning of LED color status

RUN green turns off the Initiat (initialization) or BOOTSTRAP (firmware update mode)

Flashing PREOP (email communication available, no process data)

Single flash SAFEOP (output in safe state, process data not activated)

Always on OP (normal operation, process data communication is normal)

Encoder green constant light, encoder ready

A/B/C green constant light corresponds to encoder input signal

Latch green constant light latch input has signal

Input 1/2 green constant light digital input 1/2 is high level (24V)

2.2 Driver and Error LED (Right Prism)

Meaning of LED color status

Driver green constant light output stage ready

Power green off, motor power supply voltage missing or motor control disabled

The power supply voltage of the constantly on motor exists

Turn CW/CCW green constant light motor is rotating forward/reverse

Enable green extinguishing motor control disabled (object 0x7010:01 not set)

Constant brightness motor control activated

Warning yellow constant light configuration error: motor power supply not connected, temperature>80 ° C, duty cycle 100%, etc

Error A: Red constant light, Phase A output stage error: Temperature>100 ° C, short circuit, etc

Error B: Red constantly on, Phase B output stage error: Temperature>100 ° C, short circuit, etc

2.3 K-bus/E-bus diagnosis

When the terminal is connected to the K-bus (bus terminal), the K-BUS ERR LED of the power terminal will indicate an error with a specific flashing code (see the subsequent troubleshooting section of this article). When connected to the E-bus (EtherCAT terminal), the L/A LED flashes to indicate data communication.

CoE parameter configuration and key objects

All operational parameters of EL70x7 are configured through the CANopen over EtherCAT (CoE) object directory. The following are the most commonly used objects in on-site debugging.

3.1 Basic parameters of motor (0x8010)

Index Name Unit Description

0x8010:01 Maximum current 1 mA Maximum continuous coil current. EL7037 defaults to 5000mA (5A), but the actual terminal rating is limited.

0x8010:02 Reduced current 1 mA Reduced current at rest (energy-saving mode)

0x8010:03 Nominal voltage 10 mV motor rated voltage (non supply voltage). Used for model calculations.

0x8010:04 Motor coil resistance 10 m Ω Motor phase resistance

0x8010:05 Motor EMF 1 mV/(rad/s) Back electromotive force constant (for sensorless mode)

0x8010:06 Motor full steps - The number of motor full steps. Usually 200 (1.8 ° step angle)

0x8010:07 Encoder increments (4-fold) The number of pulses per fourth harmonic of the encoder per revolution. AS10xx motor comes standard with 1024 inc → 4096

3.2 Operation Mode and Function Selection (0x0012)

Description of allowed values for sub index names

0x8012:01 Operation mode 0=automatic, 1=direct speed, 3=position control, 4=extended speed, 5=extended position, 6=no sensor default 0 (automatic mode, automatically switched according to PDO)

0x8012:05 Speed range 0~5 corresponds to a maximum stride frequency of 1000~32000 full steps/s. Default 2000 full steps/s

0x8012:08 Feedback type 0=encoder, 1=internal counter position feedback source. Default internal counter

0x8012:09 Invert motor polarization 0/1 Reverse motor rotation direction

0x8012:0A Error on step loss 0/1 Do you consider step loss as an error

0x8012:0B Fan cartridge present 0/1 Notify that ZB8610 fan has been installed on the terminal

3.3 Positioning Interface Parameters (0x0020)

When using the Positioning interface mode, the following parameters are used for stroke control:

Index Name Range/Unit Description

0x8020:01 Velocity min. 0-10000 Minimum set speed (percentage of speed range)

0x8020:02 Velocity max. 0-10000 Maximum set speed

0x8020:03/04 Acceleration pos./neg. ms Forward/reverse acceleration time (from 0 to 100% speed)

0x8020:05/06 Deceleration pos./neg. ms forward/reverse deceleration time

0x8020:07 Emergency deceleration ms Emergency stop deceleration time

0x8020:08 Calibration position inc is the absolute position set after completing the zeroing process

0x8020:0B Target window inc Target window, within this range is considered 'arrived'

0x8020:0E Modulus factor inc Modulus factor (such as the increment corresponding to 360 °)

3.4 Controller Parameters (0x8014)

Index Name Description

0x8014:01 Feed forward (pos.) position feedforward

0x8014:02 Kp factor (pos.) position loop proportional gain

0x8014:03 Kp factor (velo.) Speed loop proportional gain (unit: 0.1 mA/(rad/s))

0x8014:04 Tn (velo.) velocity loop integral time constant (unit: 0.01 ms)

Detailed explanation and selection of operating modes

EL70x7 supports multiple operating modes, each suitable for different application scenarios and motor types.

4.1 Automatic mode (default)

The terminal automatically switches between speed and position controllers based on the selected predefined PDO allocation. Not applicable to extended mode. For applications that do not require magnetic field orientation control, this mode is recommended.

4.2 Velocity direct mode

Set the speed through the loop variable STM Velocity (0x7010:21), with a range of ± 32767 corresponding to ± 100% speed range.

Support internal counter or encoder feedback.

It can be controlled through TwinCAT NC or direct PLC.

4.3 Position controller mode

Set the target position in increments using STM Position (0x7010:11).

When using an internal counter, one revolution of AS10xx motor corresponds to an increment of 12800, which is 200 full steps x 64 micro steps.

When using an external encoder, one circle corresponds to 4 encoder lines (e.g. 1024 lines → 4096 increments).

4.4 Extended Velocity/Position Mode

Based on field oriented control (FOC), the stepper motor is controlled as a servo motor.

Only supports Beckhoff AS10xx series motors.

An encoder must be connected with a resolution of at least 4000 inches per revolution.

When enabled, commutation determination needs to be performed: the rear axle will be slightly swung forward and backward several times to determine the rotor position. During this period, the external load torque must be extremely small.

Advantages: Completely eliminate resonance, load adaptive current, high efficiency, and no step loss.

4.5 Velocity sensorless mode

By analyzing the back electromotive force, load adaptive current control can be achieved without the need for an encoder.

Only supports Beckhoff AS10xx motors.

Only valid within the medium to high speed range, automatically switches back to standard mode at low speeds. The switching speed can be set through the Cross over velocity parameter (0x0014:07-09).

The dynamic performance is slightly lower than the expansion mode, but it has high energy efficiency and low cost.

4.6 Positioning interface

Closed loop position control within the terminal, no TwinCAT NC license required.

Send travel commands through POS Output object (0x7020), supporting multiple Start types such as absolute, relative, incremental, modular, and zero return.

Status feedback through POS inputs (0x6020): Busy, In Target, Warning, Error, Accelerate, Decelerate.

Suitable for simple, cost sensitive single axis applications, but with lower synchronization accuracy and functional flexibility than NC control.

Troubleshooting: DiagMessages and Common Error Codes

EL70x7 supports the ETG.1020 diagnostic message system, where all events (warnings, errors, status changes) are stored in the CoE object 0x10F3 and can be viewed through the "Diag History" tab of TwinCAT. The following are the most common errors and solutions on site.

5.1 Terminal cannot enter OP state

Reason: PDO configuration and operation mode do not match; Watchdog triggered; E-bus power supply is insufficient.

Solution: Check if the PDO assignment in the "Process Data" tab is compatible with the selected operating mode (e.g. speed mode must include STM Velocity PDO). Check the E-bus current calculation and insert the EL9410 power supply input terminal if necessary. View the 'invalid SM cfg' information in the TwinCAT log.

5.2 Motor not rotating or shaking

Reason: Incorrect connection of motor winding (A1/B1 mixed connection); The power supply voltage is too low; Enable position not set; Encoder signal malfunction.

Solution: Verify the winding wiring (use a multimeter to measure resistance and distinguish phases). Check if the Enable bit (0x7010:01) is true. Check if the Power LED is on. If using the extended mode, confirm that the encoder signal is normal and the commutation angle measurement has been completed.

5.3 Overheating Warning/Error (Text ID 0x4101/0x8104)

Reason: The internal temperature of the terminal exceeds 80 ° C (warning) or 100 ° C (error).

Solution: Check if the installation position is correct (vertical ventilation). Reduce the motor current (0x8010:01) or enable static current reduction (0x8010:02). Installing the ZB8610 fan module can increase the rated current by 30%.

5.4 Overcurrent/Short Circuit (Error 0x8404, LED Error A/B constantly on)

Reason: Short circuit of motor winding or ground; The output stage is damaged.

Solution: Disconnect the motor and use a multimeter to measure the insulation resistance between the windings and the casing. If there is a short circuit on the terminal side, the terminal needs to be replaced. Check the load voltage fuse.

5.5 DC bus undervoltage/overvoltage (warning 0x4411/0x4412, error 0x8406/0x8407)

Reason: The supply voltage is lower than 7V or higher than 110% of the rated voltage.

Solution: Measure the motor supply voltage on the power terminal to ensure it is within the range of EL7037 (24V ± 20%) or EL7047 (8-48V). A very short deceleration slope may cause energy feedback boost, requiring parallel connection of buffer capacitor terminal EL9570.

5.6 Step Loss Detection (Warning 0x4416)

Reason: The load torque exceeds the motor's capacity; The acceleration and deceleration slope is too steep; Insufficient current setting.

Solution: Increase the current (0x8010:01), prolong the acceleration and deceleration time (0x8020:03-06), or choose a larger torque motor. If Error on step loss (0x8012:0A) is enabled, step loss will trigger an error and stop output.

5.7 Encoder Error (Text ID 0x8301~0x8312)

Common codes: 0x8302 (encoder amplitude too small), 0x8304 (communication error), 0x8309 (CRC error).

Solution: Check the encoder cable shielding and wiring, and confirm that the encoder power supply (+24V) is normal. For absolute value encoders such as EnDat, check protocol compatibility.

Firmware update and factory reset

6.1 Precautions for firmware update

Only use TwinCAT 3 for firmware updates, and the system is in Config/FreeRun mode (no license required).

It is necessary to ensure that EtherCAT communication has no CRC errors or frame loss.

During the update process, it is absolutely forbidden to disconnect the power or network, otherwise the terminals may be permanently damaged and need to be returned to the factory for repair.

6.2 Update Steps (Taking *. efw Controller Firmware as an Example)

Switch TwinCAT to Config/FreeRun mode with a cycle time of ≥ 1ms.

In the Online tab, switch the target terminal to the Initiat state and then to the BOOTSTRAP state.

Click on 'Download' and select the latest *. efw file. Usually no password is required.

After the download is complete, switch back to Initialize and then switch to PREOP.

Disconnect the power supply from the terminal and power it back on (non hot restart), then check if the firmware version number in CoE 0x100A has been updated.

6.3 Factory reset

Go to the CoE Online tab and find object 0x1011:01 (Restore default parameters).

Enter 0x64616F6C (ASCII "load") in the Set Value dialog box and confirm.

All BackUp objects will be reset to factory settings. This operation can be automatically executed through the startup list for automatic parameterization when replacing terminals.

Maintenance recommendations and spare parts information

Recommended cycle notes for inspection items

The fastening of motor wiring terminals may become loose due to annual vibration, causing poor contact and overheating.

Ventilation openings should be cleaned every six months using a vacuum cleaner to remove dust, and the use of compressed air is prohibited.

If the fan module (ZB8610) is used continuously for 5 years, it is recommended to replace it preventively.

Parameter backup (startup list): Export the CoE configuration to the startup list after each modification for easy terminal replacement.