wmx_ros2_message#

Overview#

The wmx_ros2_message package defines custom ROS2 message and service interfaces used by all nodes in the WMX ROS2 application. It contains no executable nodes – only interface definitions that are compiled into C++ and Python bindings by rosidl.

Package Metadata:

Package Name	`wmx_ros2_message`
Version	0.1.0
License	MIT
Build Type	`ament_cmake`

Package Structure#

wmx_ros2_message/
├── CMakeLists.txt
├── package.xml
├── msg/
│   ├── AxisPose.msg
│   ├── AxisState.msg
│   └── AxisVelocity.msg
└── srv/
    ├── SetEngine.srv
    ├── SetAxis.srv
    ├── SetAxisGearRatio.srv
    ├── LoadWmxParams.srv
    ├── GetWmxParams.srv
    ├── GetIoBit.srv
    ├── GetIoBytes.srv
    ├── SetIoBit.srv
    ├── SetIoBytes.srv
    ├── EcatGetNetworkState.srv
    ├── EcatRegisterRead.srv
    ├── EcatResetStatistics.srv
    └── EcatStartHotconnect.srv

Dependencies#

Dependency	Type	Purpose
`ament_cmake`	buildtool	CMake build system
`rosidl_default_generators`	build	Message/service code generation
`std_msgs`	depend	`std_msgs/Header` used by `AxisState`
`rosidl_default_runtime`	exec	Runtime message type support
`ament_lint_auto` / `ament_lint_common` / `ament_cmake_gtest`	test	Linting and tests

The package is a member of the rosidl_interface_packages group, which allows other packages to discover its generated interfaces at build time.

Message Definitions#

AxisPose#

Used for absolute and relative position motion commands. Subscribed by wmx_core_motion_node on /wmx/axis/position and /wmx/axis/position/relative.

int32[]   index       # Axis indices to command
float64[] target      # Target positions (radians)
float64[] velocity    # Motion velocity per axis (rad/s)
float64[] acc         # Acceleration per axis (rad/s²)
float64[] dec         # Deceleration per axis (rad/s²)

All array fields are parallel – element i in each array corresponds to the same axis.

AxisVelocity#

Used for continuous velocity motion commands. Subscribed by wmx_core_motion_node on /wmx/axis/velocity.

int32[]   index       # Axis indices to command
float64[] velocity    # Target velocity per axis (rad/s)
float64[] acc         # Acceleration per axis (rad/s²)
float64[] dec         # Deceleration per axis (rad/s²)

AxisState#

Comprehensive per-axis status feedback published at 100 Hz by wmx_core_motion_node on /wmx/axis/state.

std_msgs/Header header

# Status flags (per axis)
bool[] amp_alarm        # Amplifier alarm active
bool[] servo_on         # Servo enabled
bool[] home_done        # Homing completed
bool[] home_switch      # Home switch triggered
bool[] negative_ls      # Negative limit switch triggered
bool[] positive_ls      # Positive limit switch triggered
bool[] motion_complete  # Motion finished / in position

# Command and feedback values (per axis)
float64[] pos_cmd          # Commanded position (radians)
float64[] velocity_cmd     # Commanded velocity (rad/s)
float64[] actual_pos       # Actual encoder position (radians)
float64[] actual_velocity  # Actual velocity (rad/s)
float64[] actual_torque    # Actual torque

Service Definitions#

Engine#

SetEngine – controls the WMX engine lifecycle (device creation and communication). Used by /wmx/engine/set_device on wmx_engine_node.

# Request
bool   data      # true = create device, false = close device
string path      # WMX3 device path (e.g., "/opt/wmx3/")
string name      # Device name identifier
---
# Response
bool   success   # true if operation succeeded
string message   # Human-readable result description

Axis Control#

SetAxis – generic per-axis control. The meaning of data depends on the service using it.

int32[] index    # Axis indices (e.g., [0, 1, 2, 3, 4, 5])
int32[] data     # Per-axis values (meaning varies by service)
---
bool   success   # true only if ALL axes succeeded
string message   # Concatenated per-axis result messages

Used by /wmx/axis/set_on (1=enable / 0=disable), /wmx/axis/clear_alarm (data unused), /wmx/axis/set_mode (0=position / 1=velocity), /wmx/axis/set_polarity (1=normal / -1=reversed), and /wmx/axis/homing (data unused).

SetAxisGearRatio – configures the encoder gear ratio per axis. Used by /wmx/axis/set_gear_ratio.

int32[]   index         # Axis indices
float64[] numerator     # Gear ratio numerators
float64[] denominator   # Gear ratio denominators
---
bool   success
string message

Parameters#

LoadWmxParams – load axis parameters from a WMX3 XML file (/wmx/params/load).

string file_path   # absolute path to the WMX3 XML parameter file
---
bool   success
string message

GetWmxParams – retrieve active axis parameters as text (/wmx/params/get).

int32[] index          # axis indices to report
---
bool     success
string   message
string[] params_dump   # formatted, human-readable parameter dump

I/O#

GetIoBit / SetIoBit – read/write a single digital I/O bit.

# GetIoBit request          # SetIoBit request
int32 byte                  int32 byte
int32 bit                   int32 bit
---                         int32 value
bool   success              ---
int32  value                bool   success
string message              string message

GetIoBytes / SetIoBytes – read/write a contiguous block of I/O bytes.

# GetIoBytes request        # SetIoBytes request
int32 byte                  int32 byte
int32 length                uint8[] data
---                         ---
bool    success             bool   success
uint8[] data                string message
string  message

EtherCAT#

EcatGetNetworkState – full master + per-slave network state.

int32 master_id
---
bool   success
string message
int32  master_state      # 0=None 1=Init 2=Preop 4=Boot 8=Safeop 16=Op
int32  master_mode
uint32 comm_period
uint32 total_axes
uint32 packet_loss
uint32 over_cycle
int32  num_of_slaves
int32[]  slave_ids
int32[]  slave_states
bool[]   slave_offline
bool[]   slave_inaccessible
uint32[] slave_vendor_ids
uint32[] slave_product_codes
# (plus additional timing and addressing fields)

EcatRegisterRead – read raw register data from a slave.

int32 master_id
int32 slave_id
int32 reg_address   # 0x000–0xFFF
int32 length        # 1–4096 bytes
---
bool    success
uint8[] data
string  message

EcatResetStatistics / EcatStartHotconnect – both take only int32 master_id and return bool success + string message.

Building the Package#

This package must be built before wmx_ros2_package because the main package depends on the generated message headers:

cd ~/workspaces/movensys_ws
colcon build --packages-select wmx_ros2_message
source install/setup.bash

Verify the interfaces are registered:

ros2 interface list | grep wmx

Expected:

wmx_ros2_message/msg/AxisPose
wmx_ros2_message/msg/AxisState
wmx_ros2_message/msg/AxisVelocity
wmx_ros2_message/srv/EcatGetNetworkState
wmx_ros2_message/srv/EcatRegisterRead
wmx_ros2_message/srv/EcatResetStatistics
wmx_ros2_message/srv/EcatStartHotconnect
wmx_ros2_message/srv/GetIoBit
wmx_ros2_message/srv/GetIoBytes
wmx_ros2_message/srv/GetWmxParams
wmx_ros2_message/srv/LoadWmxParams
wmx_ros2_message/srv/SetAxis
wmx_ros2_message/srv/SetAxisGearRatio
wmx_ros2_message/srv/SetEngine
wmx_ros2_message/srv/SetIoBit
wmx_ros2_message/srv/SetIoBytes

Inspect a specific interface:

ros2 interface show wmx_ros2_message/msg/AxisState