Circular Interpolation

Circular interpolation is used to move two axes in a circular path based on the target position and type of circular interpolation mode.

  • The XPM_IST function block is used to execute the circular interpolation from the Position data table.

  • The axes being controlled must already be configured using the XG-PM software before using XPM_IST.

Video Tutorial

XPM_IST Details

Element Name Element Type Description
REQ Input Edge detected request to execute the function block
BASE Input Base number of the motion controller.Equal to 0 for built-in position control.
SLOT Input Slot number of the motion controller.Equal to 1 for built-in position control
AXIS Input Axis number of the main axis for the circular interpolation move.Set to 1 thru 6 for built-in axes. This can be a constant or variable.
STEP Input Step to execute in the position table.Must be a value between 0 – 400.If value is set to 0, then the current step is executed.This can be a constant or variable.
DONE Output Status that function block is done.
STAT Output Current status of the function block.Non-zero numbers will be an error or warning.

 

This example shows control of Axis 1 and 2 by an XEM-DN32HP CPU.

  • Axis 1 is the main axis and Axis 2 is the sub axis.

  • The first example is doing a complete circle using circular interpolation.

  • The second example is doing a spiral movement using circular interpolation.

Step Action
1

Open the XG5000 project for the application. Go to Tools menu è Position Control to open XG-PM software.
2

Open the XG-PM project or connect to PLC and select Projectè Open from PLC.
3

Open the Parameter file in the Workspace for the axis that is being configured. This example shows Axis #1.

This parameter screen will open:
4

Configure the parameters of the Axis. This example shows Axis 1.
5 Configure Axis 2.
6

Save the project. Connect to the CPU and write the project to the CPU.

Note: If connecting XG5000 and XG-PM at the same time, make sure to connect XG5000 first. XG5000 will give error messages if it is connected last.

The Position table is setup in the XG-PM software.

Step Action
1

Open the XG5000 project for the application. Go to Tools menu è Position Control to open XG-PM software.
2

Open the XG-PM project or connect to PLC and select Projectè Open from PLC.
3

Open the Position Data table in the Workspace for the axis that is being configured. This example shows Axis #1.

The position data table will open:
4

For the examples, we will configure the Position data table with these entries:

  • The same step number needs to be used for both the main and sub axes.

  • Example 1: Step 1 for Axis 1 and 2 will perform a complete circle with a center point at 1,000 pulses. Axis 2 Control type must match Axis 1 for a Relative circular interpolation move. Cir. int. mode can be Center-Point CW or Center-Point CCW.

  • Example 2: Step 15 for Axis 1 and 2 will perform a spiral movement. Axis 2 Control type can be default for an Absolute circular interpolation move. Cir. int. mode must be Center-Point, CW for this example.

See each example below for details.

  • In this example Axis 1 is the main axis and Axis 2 is the sub axis.

  • The control types of Axis 1 and Axis 2 must match when using a relative circular interpolation move.

  • The Target positions should be equal to 0 to move in a complete circle using relative circular interpolation.

  • The circular interpolation mode can be set to Center-Point, CW or Center-Point, CCW.

  • A valid circular interpolation auxiliary point (center point) must be entered.

  • In this example the starting points for Axis 1 and 2 are (0,0). The center point of the circle is chosen to be (1000,1000)

XPM_IST Code for Example 1:

XG5000 Trend of Example 1:

  • Start position for this move is (200, 1500).

  • The circular interpolation mode must be set to Center-Point, CW for Axis 1. Axis 2 can be Middle-Point or Center-Point, CW.

  • Axis 2 Circular interpolation auxiliary point must equal start position for Axis 2.

  • Axis 2 Target position must be a lower value then the start position.

  • Axis 1 Circular interpolation turns should be set to value higher then 1. This will allow the interpolation to be performed more then 360 degrees.

XPM_IST Code for Example 2:

XG5000 Trend of Example 2:

 

 

 

 

 

LP522