RTDE background
===============
.. raw:: html
.. raw:: html
What RTDE is
------------
RTDE is the Universal Robots Real-Time Data Exchange interface. In practice, it lets an external application synchronize selected robot data over TCP.
This project follows the official RTDE model closely:
- choose named output fields,
- optionally choose input fields,
- start the synchronization loop,
- read robot outputs and write controller inputs.
Why field names are kept literal
--------------------------------
The web interface and the Python API deliberately use the real RTDE field names so that what you configure here matches the names in the official Universal Robots RTDE documentation.
Examples:
- ``timestamp``
- ``actual_q``
- ``actual_qd``
- ``actual_current``
- ``actual_TCP_pose``
- ``input_int_register_24``
- ``output_int_register_24``
Output recipe vs input recipe
-----------------------------
RTDE uses:
- **one output recipe** for robot-to-client streaming,
- **one or more input recipes** for client-to-controller writes.
In this project, you normally only have to think in terms of fields and whether they are readable or writable.
GP inputs vs GP outputs
-----------------------
The most important practical distinction is:
- ``input_*_register_*`` is writable from the client.
- ``output_*_register_*`` is readable from the client.
For external RTDE clients the commonly used ranges are:
- ``input_bit_register_64`` .. ``input_bit_register_127``
- ``input_int_register_24`` .. ``input_int_register_47``
- ``input_double_register_24`` .. ``input_double_register_47``
- ``output_bit_register_64`` .. ``output_bit_register_127``
- ``output_int_register_24`` .. ``output_int_register_47``
- ``output_double_register_24`` .. ``output_double_register_47``
Frequency and load
------------------
The web interface can request high RTDE rates, but that does not mean every visualization layer should try to consume every frame.
Practical rule of thumb:
- use **500 Hz** only with a slim field list,
- use **125 Hz** for richer monitoring,
- add current, GP, and diagnostics fields only when you need them.
Current-window view
-------------------
To compare measured current against the allowed deviation window, request these fields together:
.. code-block:: python
ROBOT_FIELDS = [
"timestamp",
"target_current",
"actual_current",
"actual_current_window",
]
The web interface derives a practical ratio:
.. code-block:: text
usage = abs(actual_current - target_current) / actual_current_window
That ratio is a monitoring aid, not a certified safety function.