#### Mode list

The Mode list in the Advanced Measurement Options area determines how the nominals will be computed for a given point. PC-DMIS allows you to choose between FIND NOMS, MASTER, and NOMINALS.

If MODE = NOMINALS is active, PC-DMIS will compare the measured feature with the theoretical data in the dialog box, using the measured data for calculations.

If MODE = MASTER is active, then PC-DMIS will use the measured feature as the nominal, but will not update the X, Y, Z and diameter data in the dialog box.

If MODE = VECTOR is active, then PC-DMIS will use your first three hits to calculate the appropriate vector to use for the feature. PC-DMIS will not adjust the location of the feature. You must take the hits with the Auto Features dialog box active.

Note: If a nominal value is not known, simply select FIND NOMS from the list. While this option is active, every time a value is selected to be changed, PC-DMIS will prompt you to take the appropriate measurements on the part to obtain the values needed.

List Item | Description
Find Noms | When you select FIND NOMS from the Mode list, PC-DMIS will pierce the CAD model to find the closest location on a CAD edge (or surface) to the measured point, and set the nominals to that location on the CAD element. To find the nominals using CAD data:

1. Verify that PC-DMIS is set to Curve mode or Surface mode (available from the Graphics Modes toolbar), as is appropriate for the particular part program.

2. Click on the desired CAD element in the Graphics Display window. PC-DMIS will pierce the CAD element to obtain the location, but will not create a feature. Once the desired elements have been selected, PC-DMIS will automatically fill in the X, Y, Z and I, J, K values.

3. If the values are satisfactory, select the Create command button.

CAUTION: If you select the Measure box, PC-DMIS will measure the part.

If a hit is taken on the part while in FIND NOMS mode, PC-DMIS will search through the CAD elements and find the nominal CAD information that is closest to the measured point. If necessary, PC-DMIS will prompt you to take any additional hits on the part.

The next time the part is measured, PC-DMIS will set the nominal data to the nearest CAD element it can find. The mode switch will then be reset to NOMINALS.

Using Find Noms with Fixed Probes:

Faro or Romer arms using a fixed probe don't generate good approach vectors. Because of this, PC-DMIS cannot easily determine where to look for the surfaces.

To improve vectors from fixed probes:

1. Place the fixed probe on the part.

2. Press the Hit button.

3. Move the probe away from the part along the approximate surface vector.

4. Press the End button.

PC-DMIS will calculate and then use the vector between the hit and the probe tip's position.

Also, because the default vector from a Faro arm uses the axis of the fixed probe, the more you position the vector normal to the surface the more useful the vector is for Find Noms operations.

Master | If a point is created when the Mode list is set to MASTER, then the next time the part is measured, PC-DMIS will set the nominal data equal to the measured data. The Mode list will then be reset to NOMINALS.
Nominals | The NOMINALS option also requires you to have nominal data before the measurement process begins. PC-DMIS will compare the measured feature with the theoretical data in the dialog box, using the measured feature for any necessary calculations.
Vector | The VECTOR option allows you to update only the feature's vector during learn mode; it will not update the nominal XYZ values. This option helps you to set a feature's vector that you may not be able to obtain otherwise. With the dialog box open, take three hits on the feature. This will determine its vector.

You can use this mode as long as the dialog box remains open. Once you close the dialog box, the option is not available for the feature in the Edit window.

Supported Features: Vector Point, Surface Point, Corner Point, Line, Plane, Circle, Ellipse, Round Slot, Square Slot, Notch Slot, Polygon, Cylinder, Cone, Sphere