Autodesk Revit Architecture

[#1]

I'm working on a user-defined structural column family in 2012.  Within the family, there is a component at the top of the column whose angle needs to be defined as an instance-specific slope (i.e. (1/3)" / 12"), not just simply an angle.  I've already created the proper slope-type parameter within the Family Types Dialog as an instance parameter.  I've created the reference plane I would like it to be based on, but I haven't actually created the component yet because I can't get the reference to behave how I need it to.

The problem is when I try to attach the value as a label on the angular dimension that controls the angle of the feature, it won't let me select it.  If I create a new parameter while labeling the dimension it automatically creates an angle parameter and won't let me choose to create a slope parameter.

I have tried creating an angle parameter and entering slope-style information into it, but it either rejects the input as invalid or comes up with something completely off-the-wall.  Since it automatically resolved the slope to an angle, I have also tried creating both slope- and angle-type parameters and linking them together using the formula angleValue = slopeValue, but it rejects this construct saying "Inconsistent Units".

Maybe I'm over thinking this because I can attach a column to a roof (assuming the roof is constructed correctly), but I'm not too sure that would accomplish what I need to because there is additional structure that needs to be placed above the column before attaching to the roof.  What can I do?

[#2 · Accepted solution]

You could handle the slope as an angle, using this formula: atan (y/x)

See illustration.

[#3]

To match my final intent, I made a slight change to the example you provided and it seems to be changing the angle of my reference plane how I would like.

I'll try to remember to post back after I've had an opportunity to attach some actual geometry to the plane.

Thanks. 

[#4]

I took Alfredo_Medina's suggestion and did some tweaking.  By doing so, I found a way to enter the slope in 1 parameter how I wanted.

First, I defined a "Roof Slope" instance parameter of type "slope".

Second, I defined another instance parameter called "Slope Angle" of type "angle".

Then, I set the formula for "Slope Angle" to atan(Roof Slope).

I then labeled the appropriate angle dimension with the "Slope Angle" parameter. 

Now, I can enter the roof slope as 1/12 and it will automatically calculate the appropriate angle.