Change a System Parameter from Type to Instance - Not Length

It is fairly common knowledge that we can change a built-in parameter like Width from Type to Instance by going through the side door, selecting a dimension assigned to the parameter and changing it to Instance on the ribbon (see the image).

Kurt Thompson wrote to me to share how he gets around this issue when the parameter isn't something a dimension can be associated with. Specifically he was referring to a thread at the Autodesk User Forums where a member (electrical focus) was asking Autodesk to change the default parameters for Mains (instance), MCB Rating (type) and Subfeed Lugs (type). They argue that each parameter should be the opposite of the current configuration based on how the information is really dealt with (not that he needs me to, but I agree with him).

Kurt writes:

"To change a System Type parameter to Instance...(specific to the mentioned thread)

Create a Shared Parameter built exactly like the built-in parameter you need to change but make it Instance instead of Type. Starting out with a Generic Model family, add the new parameter. Now assign the family to the category Electrical Equipment, Revit will replace the shared parameter with the built-in parameter but it will retain the Instance (or Type) property setting from the shared parameter. Give it a try."

Thanks Kurt!

Remember Linked Files Have Two Workset Parameters

I find this overlooked regularly. Each link has an Instance AND Type parameter called Workset. If we select a link (RVT) in the Project Browser we can see the Type parameter for workset, even if the link isn't loaded.

If we right-click and choose Select All Instances > In Entire Project we can see the Instance parameter value, unless there is more than one instance (copies of the link).

The best way to ensure that both parameter values are assigned to the same workset is to make sure the Active Workset is set correctly first, before we link the file. If not then we have to check both values.

Why are there two parameters?

The Type parameter governs the existence of the link in the database while the Instance parameter governs the actual instance you can see in the model views. The linked file can be copied, for example House Design A can be copied so we can show that it will be located on several lots within a development, each likely oriented differently.

The instance parameter allows us to assign each copy to a unique workset while the Type parameter affects all of the copies. That means closing the workset assigned to the Type parameter will close all of the copies of the link, none of them will be visible.

If we close the workset assigned to just one copy then only that linked file won't be visible.

If we experience erratic issues with linked file visibility it is the first thing I check. I'm also in the habit of looking at all the linked files every time I get introduced to project. This also applies to other linked files (CAD,Point Cloud).

Instance Parameter Comparison Revit 2012 and 2011

The manner in which Revit reacts to Instance Parameter changes to families you place has changed from version 2011 to 2012. In the past Revit regarded the changing of an instance parameter as though it was more important than the default value the family is supposed to use. This meant that any future families placed would use the value entered instead of the default value. Worsererer it affected other families of the same ilk, like a receptacle family and another receptacle family.

The good news is that 2012 pays more attention to the family default value for the individual families you place than the override. This means you can change the value for the individual family you are placing now and then if you switch to something else, when you return to place more of the families (or another type) you'll get the default value assigned to the family instead of the "rogue" change you made to one earlier.

Daniel Stine (author of several Revit books) created this video and passed it along to me (no audio) to share when he wrote to ask me if I noticed the change. I did and was grateful for the change. Since he went to the trouble to make a video, seems a shame not to share it!

IsReference Setting - Weak and Strong

I've written posts about Reference Planes in the past, these are a couple specific examples:

Once Upon a Reference Plane
Is you Is or Is You Ain't

I've neglected to mention this change: In the past using the Weak reference setting would not generate drag arrows. They've changed this at some point, which I haven't pinned down (2010ish) but I think it had to do with the changes to the massing conceptual design environment.

The Video that appears below demonstrates some subtlety between the Weak and Strong reference settings. The nice names like Front, Back, Top and Bottom are all Strong references by the way. When you combine Weak references with a dimension assigned to a Instance parameter you get "move" behavior when you use the Align tool. When you do the same for Strong references you get "stretch" behavior. If you want your family to move, think Weak. Think Strong for Stretch.