You can position a datum plane by selecting two points. Abaqus/CAE creates a datum plane midway between the two selected points and normal to the line connecting them.
To create a datum plane midway between two points and normal to the line connecting the two points:
From the main menu bar, select Tools
Datum.
The Create Datum dialog box appears. The dialog box outlines the types of datum geometry you can create.
Abaqus/CAE displays prompts in the prompt area to guide you through the procedure.
Tip:
You can also create a datum plane using the 
tool, located in the module toolbox. For a diagram of the datum tools in the toolbox, see “Using the Datum toolset,” Section 62.2.
From the list of types at the top of the dialog box, choose Plane.
The Method list indicates the methods you can use to create a datum plane.
From the Method list, select Midway between 2 points.
From the part or assembly in the current viewport, select two points.
The datum plane appears. You cannot modify a datum plane created with this method; you must delete the old plane and create a new one.
