VTClientInterfacePython.md

VT Client Interface Helper (vt_client_interface.py)

Purpose

• Provides high-level Python wrappers for nodes that communicate with vt_client_node.
• Hides raw ROS topic publish/subscribe details behind typed classes and methods.

Module

• scripts/ros2_isobus/vt_client_interface.py
• Import path after build/install: from ros2_isobus import ...

Classes

• VTContainer
  • Container visibility control only.
  • Topics: ISOBUS/vt/container/<name_token>/visible/(set|value|result).
  • Methods: set_visible(bool), visible(), visible_result().
• VTNumber
  • Number value set/get via ISOBUS/vt/number/<name_token>/(set|value).
• VTInputNumber
  • Input-number value set/get via ISOBUS/vt/input_number/<name_token>/(set|value).
  • Enable control: ISOBUS/vt/input_number/<name_token>/enabled/(set|value|result).
  • Methods: set(float), value(), on_change(...), set_enabled(bool), enabled(), enabled_result().
• VTString
  • String value set/get via ISOBUS/vt/string/<name_token>/(set|value).
• VTInputString
  • Input-string value set/get via ISOBUS/vt/input_string/<name_token>/(set|value).
  • Enable control: ISOBUS/vt/input_string/<name_token>/enabled/(set|value|result).
• VTInputBoolean
  • Input-boolean value set/get via ISOBUS/vt/input_bool/<name_token>/(set|value).
  • Enable control: ISOBUS/vt/input_bool/<name_token>/enabled/(set|value|result).
• VTList
  • List index set/get via ISOBUS/vt/list/<name_token>/(set|value).
• VTButton
  • Event input via ISOBUS/vt/event/button/<name_token>.
  • Enable control: ISOBUS/vt/button/<name_token>/enabled/(set|value|result).
  • Callback registration:
    • on_event(callback) receives raw key activation code (0/1/2).
    • on_pressed(callback) for press only (code=1).
    • on_released(callback) for release only (code=0).
• VTSoftkey
  • Event input via ISOBUS/vt/event/softkey/<name_token>.
  • Same callback API as VTButton.
• VTAuxFunction[TValue]
  • AUX function streams:
    • ISOBUS/vt/aux/<name_token>/input/value
    • ISOBUS/vt/aux/<name_token>/input/raw
    • ISOBUS/vt/aux/<name_token>/assignment/value|result
  • Accessors: input_value(), input_value_raw(), input_raw(), assignment(), assignment_result().
  • Callbacks: on_input(...), on_input_raw(...), on_assignment(...), on_assignment_result(...).
  • Pass value_type=bool, int or float to select normalized-value conversion.
• VTWorkingSet
  • Working-set level communication:
    • active/softkey mask triggers
    • status, session state
    • pointing/navigation events
    • diagnostics
    • AUX status (aux_status(), on_aux_status(...))
    • runtime pool updates (send_pool_update_xml(...))
    • runtime pool update result callback (on_updated(...))

Pool Creation And XML Usage

1. Create/edit the VT object pool with PoolEdit.
2. Export XML from PoolEdit (Export XML).
3. Configure that XML path as vt_client_node parameter xml_file.
4. Use XML name values as wrapper name_token constructor arguments.

Usage Example

import rclpy
from rclpy.node import Node

from ros2_isobus import VTButton, VTContainer, VTString, VTWorkingSet


class MyVtNode(Node):
    def __init__(self) -> None:
        super().__init__("my_vt_node")
        self.label = VTString(self, "label0")
        self.panel = VTContainer(self, "main_panel")
        self.ok_button = VTButton(self, "ok_button")
        self.ws = VTWorkingSet(self)

        self.ok_button.on_pressed(self._on_ok_pressed)
        self.ok_button.on_event(self._on_ok_event_code)
        self.ws.on_updated(self._on_pool_update_result)

        self.ws.trigger_active_mask("main_mask")

    def _on_ok_pressed(self) -> None:
        self.label.set("OK")
        self.panel.set_visible(True)

    def _on_ok_event_code(self, code: int) -> None:
        self.get_logger().info(f"ok_button event code={code}")

    def _on_pool_update_result(self, result) -> None:
        self.get_logger().info(
            f"update: success={result.success} detail={result.detail} "
            f"pending={result.pending_updates} in_progress={result.in_progress_updates}"
        )


def main() -> None:
    rclpy.init()
    node = MyVtNode()
    try:
        rclpy.spin(node)
    finally:
        node.destroy_node()
        rclpy.shutdown()

Notes

• Each object class instance is bound to one XML name_token.
• This helper assumes vt_client_node is running and has created matching topics from loaded XML.
• VTWorkingSet.send_pool_update_xml(...) can update one or many objects in one XML payload.
• AUX-N wrappers require vt_client_node parameter vt_aux_n_support:=true; the wrapper token must match an auxiliaryfunction object's XML name.