Board outline derived from case - cyclic dependency error

[jeremiahrose]

Hi there,

I am trying set up a PCB so that the outline of the board and the location of the mounting holes are determined by the case/housing design. This needs to be linked so if slight changes are made to the housing, those changes are automatically propagated to the 3D PCB and onward to the board layout.

I tried to follow the instructions in the forum post referenced here: "How to work with 3D PCB Point 9. How can I have the board outline get updated when the enclosure is changed?"

As recommended, I created a 3D PCB based on a derived sketch coming from the housing design. However, this prevents me from adding the PCB to the housing. When I try and insert the PCB into the design, I get the following error:

Error: Cyclic dependency not allowed!! The document being referenced testPCB 3D v3 already depends on the referencing document testPCB housing v3, either on disk or in memory!!

Is there something I'm doing wrong?

[rhdfmail]

I encountered the same issue last night.
I have a rough idea how my enclosure will look like and where/how the PCB will be mounted.
But since the electronics design isn't 100% finished, some extra features might be added (more space needed on frontpanel) the enclosure will probably change. 

BUT. I dont want to have the PCB  controlling the design of my enclosure. what drives the changes there is functional parts like displays, buttons and so on. 

I also want to be able to "test-fit" the PCB in the assembly. Unfortunatly it seems that we cant get all these possibilities at this time (at least not in a smooth workflow). 

[jorge_garcia]

Hi Guys,

This video may come in handy.
https://www.youtube.com/watch?v=8Ny4kWdhTbg

Shows a workflow using Insert > Derive.

Let me know if there's anything else I can do for you.

[rhdfmail]

I will give it a try, but" backwards" Enclosure first and then link them to a new assembly.
There might be some problems when I want to move components on the PCB to fit holes in the enclosure... I think

[jeremiahrose · Accepted solution]

Thanks Jorge! The solution to the problem was right at the end of the video and I almost missed it!

To summarise, you need the following file structure:

• The housing / case design
• The 3D PCB, including derived geometry from the housing (or vice-versa)
• A third "assembly" file which includes both the board and the housing and fits them together

Having the assembly as a separate file seems to avoid the cyclic dependency. It would be nice if this weren't necessary but it's a good workaround for the time-being.

[jmillerXM2T3]

The solution given thus far is to start with the PCB design first, which does not directly resolve the original question.

I have the same issue. In my case, I have several PCBs in my enclosure. The "enclosure" is the origin of the entire design. I cannot start with the PCB(s) and create a duplicate housing/enclosure because the enclosure is the source.

To prevent cyclic dependency I need to break the link somewhere but the only link I see that I can break in the generated 3D PCB is the board outline sketch. I saved a copy of my 3D PCB and 'broke' that link but I still get a cyclic redundancy error. Somehow it is still linked but I don't know where and how to break it. Of course, I lose then the ability to update my design automatically. It would be nice to have a seamless solution and well document workflow for this scenario. 

[jorge_garcia]

Hi @jmillerXM2T3 ,

I think some clarification is in order. You don't duplicate the enclosure at any point in the process. You start with the enclosure and derive PCBs from it. Whenever you want to put the two together you create a third file(the assembly file) insert the original enclosure file and the PCBs derived from it. In this way you can avoid the cyclic dependency.

Let me know if there's anything else I can do for you.

Best Regards,

[jmillerXM2T3]

Thanks for the feedback, Jorge. That makes a lot of sense. I need to learn how to best adapt my workflow, which  I hesitated doing. I get in the habit of doing everything (excepts PCBs) in one design file and that ends up getting circular in itself.  So many pieces(body/components) in my designs are based on other pieces in the same design and sometimes I need to go back and modify an earlier piece based on newer pieces. A lot of what I make is freeform like that. Making an assembly file makes good sense but I'm sure I'll discover something I need to change on one of the parts in the assembly and be tempted to modify it there. It's tempting because sometimes putting things together new references appear that are hard to translate back into one of the originating part design files without creating a circular reference. 

[HarrySatt]

Still not solved. Believe me this should not be.

Regards, Harald

@jorge_garcia 

[jorge_garcia]

Hi @HarrySatt ,

I hope you're doing well. What are you seeing specifically? The initial bug was resolved but if you are seeing something else I want to hear it.

Additionally, now we have Edit In Place which would help in these types of situations.

Let me know if there's anything else I can do for you.

Best Regards,

[HarrySatt]

Hi

In the moment I am not able to use InPlaceEdit because I use the educational version and my subscription is outdated and I am not able to renew it. I follow the instructions but no change. My email and job position did not change. FUSION360 is a bit confusing by the best.

Regards, Harald

@jorge_garcia 

@RichardHammerl 

[jorge_garcia]

Hi @HarrySatt,

I hope you're doing well. I'm trying to find out who can help you. In the mean time, it's worthwhile to open a support ticket by going to manage.autodesk.com.

Let me know if there's anything else I can do for you.

Best Regards,