topic Re: Can autocad automatically adjust a polyline while I move an object attached to one end in AutoCAD Forum

Can autocad automatically adjust a polyline while I move an object attached to one end

shortorian — Tue, 11 Mar 2025 18:49:04 GMT

I want to make P&ID and electrical diagrams with autocad, which in my current workflow would consist essentially of a set of rectangles connected by polylines (the sections of the polylines are always oriented along the x and y axes; if there’s a different tool for this let me know). I frequently need to change the layout of rectangles in a diagram after I’ve placed and connected them. I want to know if there’s a way for autocad to keep a polyline attached to an object while I move it and stretch, add, or cut sections of the polyline to keep it attached to an object at the other end of the line (which will not move as I change the position of the first object). The gif below shows the behavior I want in a different application.

Re: Can autocad automatically adjust a polyline while I move an object attached to one end

xnguyenY935A — Tue, 11 Mar 2025 17:49:59 GMT

I'm not sure if I understand this correctly, but can you group them? Grouping would automatically select both objects. Since you're only modifying one of them, the other shouldn't be affected. When you move one, both will move together—similar to a block, but without the need to name or edit it in block space. Alternatively, you could use parametric constraints to maintain the relationship between the objects. However, these can get complex quickly, so I’d recommend keeping it simple.

Re: Can autocad automatically adjust a polyline while I move an object attached to one end

shortorian — Tue, 11 Mar 2025 18:49:22 GMT

I've edited the original post to show what I want

Re: Can autocad automatically adjust a polyline while I move an object attached to one end

pendean — Tue, 11 Mar 2025 19:07:27 GMT

Short answer, no @shortorian

But... if you want to get into the Parametric Tools in the program, you might be able to give that a try.

But you are also asking in the wrong forum: P&ID is a function of the Plant3D variant, and that may be an ability it has (or not), it's best if you start there

https://forums.autodesk.com/t5/autocad-plant-3d/ct-p/2046

OR... use that other program?

Re: Can autocad automatically adjust a polyline while I move an object attached to one end

shortorian — Tue, 11 Mar 2025 19:16:57 GMT

ok, thanks. maintaining documentation over decades is hard when people rotate through an organization and use different programs for everything, so I was hoping we could use the most basic autocad toolset and get everyone using a pretty stable industry-standard program. looks like I'll either need to use the P&ID variant or choose another application that can handle a standard file format.

Re: Can autocad automatically adjust a polyline while I move an object attached to one end

imadHabash — Wed, 12 Mar 2025 04:52:18 GMT

Hi,

This is NOT applicable !!

AutoCAD can just treat with existing elements. AutoCAD cannot add or delete lines as shown in OP.

Re: Can autocad automatically adjust a polyline while I move an object attached to one end

xnguyenY935A — Wed, 12 Mar 2025 14:57:07 GMT

as @ imadHabash noted, Autocad can not add a line. The most you can do is make a block with a move parameter and some parametric constraints. I made a quick block to cover 1 case of this design. You'll need to add some visibility states to cover other types of PIDs, which at the end I think it may just be simplier to use Plant 3D.

Re: Can autocad automatically adjust a polyline while I move an object attached to one end

shortorian — Wed, 12 Mar 2025 15:48:09 GMT

Unfortunately, as far as I can tell, plant 3D doesn’t have this feature
either.

I’m going to look into EAGLE with fusion 360, but it looks like we might
have to go with draw io or a similar diagramming tool. The reason I want to
use a proper CAD program is to have fine control over component libraries,
object dimensions, and printed formats. Diagramming tools I’ve seen,
including draw io, have some capabilities like that but don’t make it easy
to do complete, maintainable technical drawings.