Skip to main content

Forecast for Single-Axis Movements

The BasicMotion_Forecast.project sample project is located in the installation directory of CODESYS under ..\CODESYS SoftMotion\Examples.

This example shows how to define a forecast for an axis in order to get information about the state of the axis in the future.

In the example, an absolute movement is executed on an axis to position 10. By setting a forecast of 300 ms on the axis, you can find out in advance in the application when and with what dynamics the axis will move through position 8.

For more information all about the forecast for axes, see: Forecast

Structure of the application

The application consists of a PLC_PRG program and a Trace.

  • PLC_PRG

    The virtual axis is switched on in the STATE_POWER_DRIVE state. Then the SMC_SetForecast function block is used to define a forecast of 300 ms for the axis in the STATE_SET_FORECAST state. The SMC_GetForecast function block can be used to read the set forecast for the axis.

    In the STATE_MOVE_TO_POSITION state, an absolute movement to position 10 is executed. The SMC_GetTravelTime function block is also started. The function block is used to read the time when the axis will reach position 8. The SMC_ReadSetValues function block is used to determine the dynamics at position 8. A time offset can be passed to this function block where the dynamics of the axis should be read. In our case, we pass the duration which the axis needs to reach position 8.

  • Trace

    You can use the trace to track the movement of the virtual axis. The current position, velocity, and acceleration of the axis are recorded. The duration up to position 8 and the dynamics of the axis at this position are also displayed.

    Note that the duration of SMC_GetTravelTime is specified relative to the start of the cycle. The set values of the axis correspond to those at the end of the cycle.

Commissioning

  1. Build the application and download it to a controller.

  2. Start the trace and the application.

  3. In the trace, you can track the movement of the virtual axis. Pay attention to the duration up to position 8 and the dynamics at position 8.

: