The 
Surface Connectivity Diagnostic tool is used to identify free or non-manifold surface edges in the model. These defects are analogous to those that occur with meshed models, however, it is advantageous to correct these problems in the geometry model before meshing. If connectivity defects exist, they can be corrected using the Surface Repair Tools in the Modeling menu.
To access this tool, import a geometry file, e.g. IGES (*.igs), STEP (*.stp, *.step), or Parasolid (*.x_t, *.x_b, etc.) using
> Import, and then select ().
Dialog elements
- Find free edges
- Select this option if you want the diagnostic to search for surface edges that are not shared by other surfaces. In a correctly connected geometry model, each surface edge should be shared between two surfaces.
- Find non-manifold edges
- Select this option if you want the diagnostic to search for surface edges that are shared by more than two surfaces. In a correctly connected geometry model, each surface edge should be shared between two surfaces.
- Display or text
- Specifies whether to show the diagnostics results as a graphical representation or a text report (not available for all diagnostics).
- Display mesh/model
- Specifies whether to display only the diagnostic results, or to display the model along with the diagnostic results.
- Place results in diagnostics layer
- Specifies whether to store the results of the mesh/surface diagnostic in a layer, separate from other layers. If you select this option, the diagnostic command automatically creates a diagnostic layer if none existed previously.
- Restrict to visible entities
- When this option is off, the diagnostic check is performed on all instances of the relevant entity when you display the diagnostic plot. Every time you make a change to the model, the displayed diagnostic plot is automatically updated. For large models, the automatic update of the diagnostic plot as you make each change to the model can lead to considerable delays, particularly when editing the mesh to resolve element overlaps or intersections.
When this option is on, the diagnostic check is performed only on visible entities. By hiding parts of the model and leaving only areas of interest visible, you can increase the plot update speed and work more efficiently.
Select Restrict to visible entities, which is normally used in combination with Place results in diagnostics layer, and click Show. With the problem elements on the Diagnostic results layer, expand the layer. Each time Apply is clicked on a mesh editing tool while cleaning up problem elements, the diagnostic will be recalculated on only the visible elements.