.. _set_velj_rt:

set_velj_rt
------------------------------------------
This function sets the joint velocity value used by :ref:`servoj_rt <servoj_rt>` in real-time control on DRCF v2; on DRCF v3, ``servoj_rt`` does not use it. It does **not** limit the ``servoj_rt`` trajectory, which follows the target position, velocity, acceleration and time of each command, and :ref:`speedj_rt <speedj_rt>` does not use it.

**Definition** |br|
``DRFLEx.h`` within class `CDRFLEx`, public section

.. code-block:: cpp

   bool set_velj_rt(float vel[NUM_JOINT]) {
       return _set_velj_rt(_rbtCtrlUDP, vel);
   };

**Parameter**

.. list-table::
   :widths: 25 20 20 35
   :header-rows: 1

   * - **Parameter Name**
     - **Data Type**
     - **Default Value**
     - **Description**
   * - vel
     - float[6]
     - -
     - Joint velocity [deg/s]. Each value must not exceed the joint velocity limit of the safety settings.

**Note**

- The controller applies this value only while real-time control is started with :ref:`start_rt_control <start_rt_control>`. A command sent before start_rt_control is ignored.
- A value above the joint velocity limit of the safety settings is rejected, and the controller reports a warning through :ref:`set_on_log_alarm <set_on_log_alarm>`. The joints before the first out-of-range joint take the new values; that joint and the later ones keep their previous values.
- To cap how fast the robot moves under ``servoj_rt``, use the joint velocity limit of the safety settings; exceeding it stops the robot.
- The value stays in effect until it is changed or the controller restarts. Ending the real-time control session does not reset it.

**Return**

.. list-table::
   :widths: 20 80
   :header-rows: 1

   * - **Value**
     - **Description**
   * - 1
     - The command was sent. This does not confirm that the controller received or applied it.
   * - 0
     - The command datagram could not be sent.

.. note::

   This function is asynchronous. It returns without waiting for the controller to accept or reject the command, so a return value of 1 does not confirm that the robot acted on it. Rejected commands and motion warnings and errors are reported through :ref:`set_on_log_alarm <set_on_log_alarm>`. :ref:`set_on_rt_log_alarm <set_on_rt_log_alarm>` reports only RT session messages, so register both callbacks.

**Example**

.. code-block:: cpp

   drfl.connect_rt_control("192.168.137.100", 12347);

   // The controller applies this value only while real-time control is started.
   // Input period 0: no input watchdog, because this example sends a single command.
   std::string version = "v1.0";
   drfl.set_rt_control_input(version, 0.0f, 4);
   drfl.set_rt_control_output(version, 0.001f, 4);
   drfl.start_rt_control();

   // Joint velocity [deg/s]
   float vel[6] = {100.f, 100.f, 100.f, 100.f, 100.f, 100.f};

   if (drfl.set_velj_rt(vel))
       printf("set_velj_rt sent.\n");
   else
       printf("set_velj_rt could not be sent.\n");

   drfl.disconnect_rt_control();

This example sets the value to 100 deg/s for every joint.

**Tips**

- The value can be changed again without restarting the real-time control session.