Beckhoff AX2000 Shutdown Braking and Debugging

Beckhoff AX2000 Servo Drive Shutdown Categories and Brake Control Debugging Guide

In the design and maintenance of industrial servo drive systems, how to achieve standard stop and emergency stop functions is the core issue to ensure personal safety and equipment integrity. The Beckhoff AX2000 series digital servo amplifier (rated current 1.5A to 20A) has become a mainstream driving component in many mechanical devices due to its wide voltage input range (3 × 208V to 3 × 480V AC), rich feedback interfaces (Resolvers, SinCos EnDat/HIPERFACE/BISS, incremental encoders), and modular fieldbus expansion capabilities (PROFIBUS, SERCOS, DeviceNet, EtherCAT). However, the safe implementation of its functionality highly depends on the correct implementation of EN 60204 Stop Categories 0/1/2, precise configuration of motor brake control timing, and strict adherence to ground/leakage current specifications. This article will be based on the technical manual of the AX2000 series, and provide an in-depth analysis of the full stack technical points of the servo drive, including mechanical installation, electrical wiring, brake control, shutdown safety circuit, and rapid debugging.

Chapter 1: Product Overview and Core Selection Parameters

1.1 Model System and Power Classification

The AX2000 series is divided into five sub models based on rated output current: AX2001（1.5A）、AX2003（3A）、AX2006（6A）、AX2010（10A）、AX2014（14A）  And AX2020 (20A). Its mechanical width increases with increasing power -70mm for 1.5A to 10A models, 100mm for 14A models, and 120mm for 20A models. All models have a uniform height of 275mm (excluding connectors) and a depth of 265mm.

1.2 Quick check of key electrical parameters

Rated supply voltage: 3 × 230V -10% to 3 × 480V+10% (50/60Hz), can be directly connected to TN or TT systems (grounding center point), with a maximum symmetrical short-circuit current of 5000A.

DC bus voltage: 290V to 675V DC (peak value allowed up to 900V).

Switching frequency: default 8kHz, can be switched to 16kHz when the bus voltage is ≤ 400V (at this time, attention should be paid to doubling the leakage current).

Integrated regenerative braking circuit: Built in regenerative resistor (66 Ω for 1.5/3A and 33 Ω for 6-20A), supports external regenerative resistor expansion, and can achieve balanced distribution of regenerative energy among multiple drivers through parallel connection of DC bus.

Chapter 2: Mechanical Installation and EMC Grounding Specification

2.1 Installation location and heat dissipation requirements

AX2000 must be installed vertically in a closed control cabinet, with an ambient temperature maintained between 0 ° C and+45 ° C (rated operating conditions); 45 ° C to 55 ° C requires a 2.5%/K derating for use. The device is equipped with a forced air cooling fan, and at least 100mm of ventilation space should be reserved at the top and bottom to ensure that cold air enters from the bottom and hot air is discharged from the top. The installation base plate should be made of conductive and unpainted galvanized metal sheet to achieve low impedance discharge of high-frequency interference.

2.2 Grounding System and Leakage Current Management

AX2000 distinguishes multiple grounding areas internally:

AGND: Analog input/output and internal μ C reference ground.

DGND: Digital input/output ground (optically isolated).

XGND: External 24V auxiliary power supply ground (photoelectric and inductive isolation).

PGND: Encoder simulation, RS232, CAN interface ground (optoelectronic isolation).

Key engineering constraints (involving personal safety): Due to the leakage current of equipment to PE typically exceeding 3.5mA (in accordance with EN50178 criteria), PE connections must use dual PE terminals (X0A and X0B in parallel) or PE wires with a cross-sectional area of ≥ 10mm ². The engineering estimation formula for leakage current is:

8kHz switching frequency: I2 leak=n × 20mA+L × 1mA/m

16kHz switching frequency: I2 leak=n × 20mA+L × 2mA/m

(where n=number of drivers, L=total length of motor cables)

Example: Two AX2000+25m motor cables, leakage current at 8kHz=2 × 20mA+25 × 1mA=65mA.

Chapter 3: Motor Brake Control and Power On/Off Timing

3.1 Electrical specifications for brake interface

AX2000 can directly drive the built-in 24V holding brake (maximum 2A) of the motor, but this function is only used for static holding and does not have a personnel safety level. The brake must be activated through the parameter BRAKE=WITH BRAKE, and its action timing is as follows:

When the ENABLE signal is removed or a fault occurs, the internal speed setting value decreases to 0 along a 10ms slope.

When the actual speed is below 5rpm (VELO parameter) or after waiting for a maximum of 5 seconds (EMRGTO), the brake output (X9 terminal B+/B -) is energized and engaged (brake lock).

The output stage was subsequently disabled.

Critical safety warning: Relying solely on the internal electronic control of the AX2000's brake output cannot achieve a safe shutdown in accordance with EN 60204 (Category 0/1). Additional positive action (forced disconnection) safety relay contacts and varistors (Varistor) must be connected in series in the brake circuit for arc extinguishing protection.

3.2 Power on/off and power failure response behavior

AX2000 has configurable response strategies for power on/off and input phase loss, controlled by parameters STOPMODE and ACTFAULT:

STOP MODE ACTFAULT fault/motor behavior during shutdown

0 (default) 1 (default) Motor free sliding stop (no control braking)

1. The motor applies controlled braking along the emergency stop ramp

Phase response (PMODE parameter):

Set as Warning (n05): Only output a warning, limit the motor current to 4A, and determine the shutdown strategy by the upper computer.

Set as Error (F19): Immediately trigger the fault, disable the output stage, disconnect the BTB/RTO contacts, and apply emergency ramp braking to the motor.

Chapter 4: EN 60204 Stop Categories Engineering Implementation

4.1 Definition of Shutdown Categories and Corresponding Scheme for AX2000

EN 60204 defines three types of shutdown, and AX2000 requires external hard wired safety relays to be used in conjunction:

Category 0- Immediately cut off the power supply

Requirement: Hard wired and positively acting electromechanical components must be used to directly cut off the main power supply of the driver, and cannot be triggered through software or communication networks.

AX2000 Implementation Plan: Connect the main contactor (K10) in series on the main power input side (L1/L2/L3) of the drive, and the emergency stop button directly cuts off the contactor coil. At the same time, the brake must also be controlled through independent electromechanical contacts (non AX2000 electronic outputs).

Limitations: This method can lead to frequent charging and discharging of the DC bus, and there is contact wear when the contactor is loaded and disconnected.

Category 1- Cut off power after controlled braking

Requirement: Maintain power supply to complete braking, and cut off power supply by electromechanical components after braking is completed.

AX2000 Implementation Plan:

After the emergency stop button is triggered, keep the 24V auxiliary power supply unchanged, but remove the ENABLE signal (or set the speed setting value to 0 through PLC).

Use the built-in brake ramp (controlled deceleration) of AX2000 to stop the motor.

Set sufficient deceleration time (t (K10t)) through a delay relay (time relay), and after the motor comes to a complete stop, disconnect the main contactor (cut off the main power supply) and the safety relay of the brake.

Must meet: The delay time must be longer than the actual deceleration time to ensure that the motor has completely stopped before cutting off the main power supply.

Category 2- Controlled shutdown but maintaining power

Requirement: The motor is controlled to shut down, but the power supply remains connected.

AX2000 Implementation Plan: Directly achieve by removing the ENABLE signal or resetting the set value to zero, without continuously opening the main contactor. Suitable for shutdowns during normal work cycles, not emergency situations.

4.2 Security application of optional AS Restart Lock

The - AS option of AX2000 is equipped with a certified safety relay (positive action contact), which can achieve personnel safety restart locking by safely cutting off the output stage drive power and short circuiting the internal set value to AGND without cutting off the main power supply.

Application Scenario:

When the safety door is opened, lock the corresponding shaft or shaft group (even if the DC bus is still live).

In teaching/setting mode, only the controlled axis is allowed to move, and the rest of the axes are securely locked.

Mandatory safety requirements:

-The monitoring contacts (KSO1/2) of AS must be connected in series to the control circuit to detect internal relay or cable disconnection faults.

Activation sequence (must be strictly followed):

Controlled deceleration to a speed of 0 rpm (set to zero).

Remove the ENABLE signal (output stage disabled).

An additional mechanical lock (such as a brake) is required to suspend the load.

Activate - AS option (safety relay powered on).

Chapter 5: Feedback Interface Configuration and Multi Feedback Combination Strategy

5.1 List of supported feedback types

AX2000 supports extremely rich feedback interfaces, which can be flexibly configured through parameters FBTYPE (main feedback) and EXTPOS/GEARMODE (auxiliary feedback):

Typical application of FBTYPE main feedback type interface

Resolver X2 0, 3 standard motor feedback, strong anti vibration performance

SinCos+EnDat 2.1 X1 3,4 high-precision absolute encoder (Heidenhain)

SinCos+HIPERFACE X1 2, 3 SICK/Stegmann encoder

SinCos+BISS X1 20 new digital protocol, supporting parameter upload

SinCos does not have a data channel X1 6, 7 and requires phase acquisition through EEPROM or Wake&Shake

Incremental encoder (RS422 5V) X5 8, 9 universal A quad B signal

Incremental encoder+Hall X1 (with Hall Dongle) 11, 12 low-cost solution with Hall commutation

5.2 Main/auxiliary feedback combination (electronic gear/master-slave application)

AX2000 supports using external encoders or pulse/direction signals as auxiliary feedback to achieve Electronic Gearing or Master Slave synchronization. The allowed combination methods are extremely flexible:

Typical scenarios of auxiliary feedback type interface GEARMODE

Incremental encoder 5V X5 3, 5, 13, 15 slave feedback in master-slave synchronization

Incremental encoder 24V X3 (DI1/DI2) 0, 2, 10, 12 long-distance transmission (stronger anti-interference)

SinCos encoder X1 6, 8, 9, 16 high-resolution position master station

SSI absolute encoder X5 7,17 external absolute value position input

Step pulse/direction 5V/24V X5/X3 1, 4, 11, 14 replace stepper motor system

Chapter 6: Fieldbus Expansion and Fast Debugging

6.1 Expansion Card Installation and Identification

AX2000 offers a variety of fieldbus expansion card options, all of which are plug and play. After insertion, the driver software automatically recognizes and activates the corresponding parameter interface:

PROFIBUS DP: Dual SubD 9 interfaces (parallel), supporting DP-V0/V1.

SERCOS: Fiber optic interface (F-SMA), supports 2/4/8/16 MBaud, requires configuration of station address (0-63) and fiber power (SLEN parameters).

DeviceNet: Rotary switch sets station address (0-63) and baud rate (125/250/500 kbps), supports Group 2 or UCMM connections.

EtherCAT: Dual RJ45 interface (IN/OUT), supporting CoE (CANopen over EtherCAT) protocol.

-2CAN -: Separate RS232 and CAN interfaces into independent SubD connectors, with built-in 120 Ω bus terminal resistance switches.

6.2 Quick Debugging Process (Quickstart)

Minimum wiring: Connect the main power supply (L1/L2/L3), 24V auxiliary power supply (X4), motor power line (X9), and feedback line (X1/X2), and connect the PC to X6 through an empty modem cable.

Start software DRIVE. EXE: Select the corresponding COM port and upload the current parameters of the driver.

Basic settings: Set the grid voltage (max. Mains Voltage), phase loss response mode (Warning/Error), and unit system.

Motor selection: Select the corresponding Beckhoff motor model from the built-in motor parameter library. If using a third-party motor, manually input the number of poles, rated current, and inductance parameters.

Feedback configuration: Select FBTYPE and verify phase angle (MPHASE) - For SinCos encoders without data channels, Wake&Shake initialization needs to be performed.

Save and Cold Start: After making critical configuration changes, it is necessary to save them to EEPROM and perform a Cold Start.

Trial operation: Verify the correctness of motor operation direction and feedback through software enable (SW Enable) and Jog function (F6 speed mode).

Chapter 7: Quick Check of Fault Codes and Troubleshooting of Common Problems

Fault code, fault description, most common causes, troubleshooting measures

F02 DC bus overvoltage regeneration energy feedback overload/external braking resistor not connected correctly. 1. Check if the X8 terminal short-circuit is removed (if an external resistor is used).

2. Measure whether the external resistance value is ≥ 33 Ω (minimum allowable value).

3. Confirm that the regeneration power parameter settings match the actual situation.

F05 DC bus undervoltage main power supply phase loss/low voltage/fuse failure 1. Measure L1/L2/L3 three-phase voltage.

2. Check the external fuse (gG type, see p.19).

F04 feedback: broken/short circuited encoder cable, broken shielding layer, loose connector. 1. Check the locking status of X1/X2 connectors.

2. Use an oscilloscope to check if the SinCos signal is normal (1Vpp).

F11 brake fault: Short circuit/disconnection of brake coil/overload of braking current. 1. Measure the resistance between B+/B - (normal value>20 Ω).

2. Confirm that the braking current does not exceed the upper limit of 2A.

N05 power phase loss warning: If one phase of the main power supply is missing (PMODE=Warning) during single-phase power supply testing, this warning is normal; If it occurs during three-phase operation, the input power supply and fuses need to be checked.

F16/F19 power supply BTB fault/phase loss error. The main power supply is severely unbalanced or lacks phase. Check the quality of the main power supply and the configuration of the upstream filtering/isolation transformer.