hdrive-etc 0.2.2

Python SDK for Henschel Robotics HDrive servo motors over EtherCAT

HDrive EtherCAT Python SDK

Control Henschel Robotics HDrive servo motors over EtherCAT from Python. No PLC required.

Web Interface

The SDK includes a full-featured browser-based GUI for motor control, monitoring, and testing.

pip install hdrive-etc
sudo hdrive-web

Then open http://localhost:8081 in your browser.

The web GUI provides:

• Real-time telemetry — live position, velocity, torque, temperature, and supply voltage
• Motor control — switch modes (torque / velocity / position), set targets, enable / disable
• Parameter tuning — adjust control bandwidth, damping, and inertia
• SDO browser — read and write any drive object
• Bus discovery — scan the EtherCAT bus and configure PDO mapping
• Built-in tests — step response, Bode plot (frequency response), inertia identification, and network latency
• Calibration — trigger encoder calibration from the browser

Control	Step Response	EtherCAT Config

Full guide with all screenshots: docs/web-interface.md

sudo hdrive-web --adapter "\Device\NPF_{...}" --slave 0 --port 8081
sudo hdrive-web --list-adapters

Raspberry Pi / Linux: The web GUI saves its configuration (adapter, slave, PDO mapping) to ethercat_config.json. When installed via pip, the default file is inside the package directory. Copy it to your working directory for easy editing:

cp $(python3 -c "import hdrive_etc, os; print(os.path.join(os.path.dirname(hdrive_etc.__file__), '..', 'ethercat_config.json'))") .
hdrive-web --pdo-config ./ethercat_config.json

Features

• Simple API — motor.set_torque(200) and you're done
• Web interface — built-in browser GUI for control, tuning, and testing
• Real-time EtherCAT — 5 ms processdata cycle via PySOEM
• CiA 402 state machine — automatic enable/disable transitions
• Thread-safe — send commands from any thread
• Context manager — automatic connect/disconnect with with statement
• SDO read/write — read and write drive configuration objects
• Auto-recovery — background thread monitors slave health

Installation

pip install hdrive-etc

Or install from source:

git clone https://github.com/henschel-robotics/python-hdrive-etc.git
cd python-hdrive-etc
pip install .

For development (editable install):

pip install -e ".[dev]"

Quickstart

1. Configure the bus (one-time setup)

Start the web interface and use it to select your adapter, scan the bus, configure PDO assignments, and save:

sudo hdrive-web          # Linux / Raspberry Pi

Open http://localhost:8081, go to the EtherCAT Config tab, click Scan Bus, then Save PDO Config. This writes ethercat_config.json with your adapter and PDO mapping.

2. Use the motor in your script

from hdrive_etc import HDriveETC, Mode
import time

# slave_index = position of the HDrive on the bus (check "Scan Bus" in the web GUI)
with HDriveETC(slave_index=0, pdo_config_path="ethercat_config.json") as motor:
    motor.set_mode(Mode.TORQUE)
    motor.set_torque(200)  # 200 mNm

    time.sleep(1)
    print(f"Position: {motor.get_position()}")
    print(f"Velocity: {motor.get_velocity():.1f} RPM")

    motor.stop()

# Motor is automatically stopped and disconnected when leaving the 'with' block

API Reference

Connect

from hdrive_etc import HDriveETC

# Recommended: use ethercat_config.json from the web interface
with HDriveETC(slave_index=0, pdo_config_path="ethercat_config.json") as motor:
    motor.set_torque(200)

# Motor is stopped and connection is closed automatically.

# Alternative: specify adapter directly (slave_index is always required)
with HDriveETC(adapter=r"\Device\NPF_{...}", slave_index=0) as motor:
    motor.set_torque(200)

Torque Control

from hdrive_etc import Mode

# Set torque in milli-Newton-metres
motor.set_mode(Mode.TORQUE)
motor.set_torque(200)   # 200 mNm

Velocity Control

# Set velocity
motor.set_mode(Mode.VELOCITY)
motor.set_velocity(300)

Position Control

# Set target position in encoder increments
motor.set_mode(Mode.POSITION)
motor.set_position(10000)

Stop

# Stop the motor (sets mode to 0)
motor.stop()

Read / Write SDO Objects

# Read a drive object (e.g. modes of operation display)
value = motor.read_sdo(0x6061, 0x00, 'b')
print(f"Current mode: {value}")

# Write a drive object
motor.write_sdo(0x6640, 0x01, 100)  # Set torque bandwidth

Telemetry

# Get motor status snapshot
status = motor.get_status()
print(f"Position: {status['position']}")
print(f"Velocity: {status['velocity']}")
print(f"Torque:   {status['torque']}")

# Individual readings
pos = motor.get_position()        # encoder increments
vel = motor.get_velocity()        # RPM
torque = motor.get_torque()       # actual torque
state = motor.get_state_name()    # CiA 402 state name

# Communication health
stats = motor.get_comm_stats()
print(f"Success rate: {stats['success_rate']:.1f}%")
print(f"Cycle time:   {stats['cycle_time_actual_ms']:.2f} ms")

Error Handling

# Read error code from drive
error_code = motor.get_error_code()
print(motor.get_error_message(error_code))

# Clear error
motor.clear_error()

Control Tuning

# Configure control parameters
motor.configure_control_parameters(
    rotor_inertia=1000,
    damping=500,
    torque_bw=100,
    velocity_bw=200,
    position_bw=300,
)

Control Modes

Constant	Value	Description
Mode.TORQUE	4	Cyclic synchronous torque (CST)
Mode.VELOCITY	-3	Cyclic synchronous velocity / stepper
Mode.POSITION	8	Cyclic synchronous position (CSP)
Mode.PROFILE_POSITION	1	Profile position mode
Mode.PROFILE_VELOCITY	3	Profile velocity mode
Mode.CALIBRATION	-99	Manufacturer calibration mode
Mode.STOP	0	Motor disabled

CiA 402 States

The motor automatically transitions through these states on connect:

State	Description
not_ready	Drive is initializing
switch_on_disabled	Drive is disabled
ready_to_switch_on	Drive is ready
switched_on	Drive is powered
operation_enabled	Drive accepts motion commands
fault	Drive is in fault state

Examples

See the examples/ folder:

• basic_control.py — Connect, apply torque, print telemetry
• velocity_mode.py — Constant speed control with direction reversal
• torque_mode.py — Torque ramp up/down
• position_mode.py — Move to a sequence of positions
• read_sdo.py — Read configuration objects via SDO

Requirements

• Python 3.8+
• PySOEM >= 1.1.0
• Npcap or WinPcap (Windows only)
  • Important: During Npcap installation, check "Install Npcap in WinPcap API-compatible Mode"
• EtherCAT-compatible network adapter
• HDrive servo motor with EtherCAT interface
• For USB-to-Ethernet adapters, use one based on the ASIX AX88772 chipset (recommended for reliable real-time EtherCAT communication) e.g. TU2-ET100

License

MIT — see LICENSE for details.

Third-party notice: This package depends on PySOEM (MIT), which wraps SOEM (GPLv3 / Commercial). Users are responsible for complying with SOEM's license terms. For commercial use of SOEM, contact RT-Labs ([e-mail]).

Support

• Email: [e-mail]
• Web: https://henschel-robotics.ch