Setting "Cyclic Synchronous Torque" (cst) mode of operation

The drive creates the specified torque. The resulting movement is dependent on the existing external conditions, for example counter-torque or total inertia. When the external load is permanently lower than the current torque of the drive, then the drive will accelerate up to the internal maximum speed of the motor. The master should therefore perform speed monitoring which is suitable for the application.

The following table shows the CiA402 objects which are required or recommended for the mode of operation. Not all objects must be located in the cyclic PDO image.

Note the maximum number of 8 entries in the cyclic PDO image (see Adapting the PDO image).

Control

Feedback

Mode of operation

Mode of operation display

Control word

Status word

Target torque

Torque actual value

Torque offset

Position actual value

Interpolation time period

Velocity actual value

Proceed as follows:

  • You have successfully started up the motor.
  • You have integrated the inverter into the TwinCAT project via network scan or offline from the device catalog, linked it to a motion axis (see Motion axis: Integrating inverters) and transferred the corresponding process data object to the PDO image (Adapting the PDO image).
  1. Set the reference units for distance (mm), angle (°), time (s), etc.
  2. Set the required user units. When doing this, pay attention to the gear unit ratio and ensure that the motor revolution remains CiA402-compliant (216 increments/revolution).
  3. Set the motion dynamics. To do this, specify the maximum speed and the up/down ramps.
  4. Set cst in the "Modes of operation" process data object. Enter the value "10" in the editor window.
    • The "Modes of operation display" process data object reports back the value "10".
    • The value "17" is displayed on the display element of the inverter.
  5. Set the torque setpoint in the "Target torque" process data object. The setpoint torque is specified in 0.1% of nominal motor torque.