CATIA PLM Weekly Email 0744 – Controlling Dimensions Using Parameters

Attn: CATIAHotline PLM’er,

So last week we talked about how to control many dimensions by using the Formula Editor. This week we are going to talk about controlling dimensions using Parameters.

Parameters are a step into knowledge based engineering (KBE) realm. I found a definition of a Parameter as “A feature defining a document or object property.” It is one of the base parts of doing KBE.

I’m going to use it to control the length of the Star that I created last week. This is pretty basic but you can see the benefits of using parameters to drive your designs.

So here we go.

First I’m opening up my Star Model


Then you will select the f(x) (‘F’ of ‘X’)


This starts up the Formula Editor


The next step will be to create a new Parameter. To do that select the ‘New Parameter of type’ Button


My good friend who is most excellent recommends renaming the Parameter that way when you go to use it it makes it easier to find it. After you rename it select Tab.


Also don’t forget to set the Value. You can set it as anything you want. But I would go with something other than Zero. Again pushing the Tab key will set the value.


Select OK. This will exit you out of the Formula Editor.This will take us back to Sketcher.

If you look in the Specification Tree and see the Parameters already shown then you can skip to the steps below by selecting here. Otherwise keep on reading on.

Select Tools -> Options. This opens up the CATSettings Panel.


Go to the (1) Options -> (2) Infrastructure -> (3) Part Infrastructure -> (4) Display -> (5) Display in Specification Tree and check the box for the (6) Parameters. Then select OK


Once that is done it should look like this.


To set the Overall length of the star to the LENGTH_POINT_TO_POINT Parameter you will right click over the value you wish to set to be the parameter and select the Edit Formula that is located under the Object menu.


The Formula Editor will appear. Last week I had you select the Value in the Sketcher Workspace. This time though you are going to select from the List.

Though there are lots of things to pick from we are going to make it easy for you. We are going to with The Parameter selection in the Dictionary listing. Then because we have renamed our Parameter we are going to select Renamed Parameters. See I told you my friend is most excellent.


Here is were it is a little bit weird. You have to double click on the Parameter you want to use or you can type it in the blank field that is located between the value that we selected and the Lists.


Now you need to define the Unit of Measurement. To do this you will Multiply that Parameter by 1 unit. For example Mine will look like this; LENGTH_POINT_TO_POINT * 1in. My unit of measurement can be any standard unit. Feet, Millimeter, Meter….


Select OK and you are back to the Sketcher Workspace.

Exit Sketcher and Now you can change the value by either Double Clicking on the LENGTH_POINT_TO_POINT Parameter or right clicking on it and selecting the Object -> Definition. Either way the Edit Parameter Panel Pops up.


You can change the value now to what ever you want. You can either type it in or you can select the arrows on the right of the Value to go in increments.

Now isn’t that to much fun. Good luck and have a great Holiday.


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