Harnessing AutoCAD Electrical and Inventor Professional to Take the Pain out of Modeling Wires

This month I'd like to discuss a topic that many Inventor users may not be familiar or comfortable with: wires. Often we spend a great deal of time figuring out precisely where all of the mechanical pieces of a machine should fit while paying little to no attention to all of those 'insignificant' details such as wires and hoses. Those 'insignificant' things that actually make our machinery work.

Why do we pay them no attention? It's not really that we feel they're insignificant; we realize their importance. But we often ignore them in our designs because they're just too difficult to model - the time required doesn't justify the benefit. What if modeling wires and wire harnesses was easier? And what if the modeling process didn't just give you a visual of the wires and harness, but allowed you to extract information that could be used to reduce costs and take time out of the build cycle by reducing prototypes? That is exactly what the Cable & Wire Harness Module of Inventor Professional allows you to do.


The Modeling Process

Ok, so maybe you've seen a cooking-show style demonstration of Pro's Cable & Wire Harness module - you know the one where the guy pushes a couple of buttons, and... Presto! You've got wires! I know I was skeptical the first time I saw such a demonstration. How much work really took place to get to that point? Hours? Days? Try minutes.


It All Starts with Parts

The process of creating wires and harnesses in Inventor Professional is actually very simple. It begins with defining 3D models of your devices and connectors such that they carry information the Harness module can use. You do this by defining work points on your models to be 'Pins' that wires are allowed to attach to.


Figure 1: Adding Pin Definitions to parts is as simple as clicking on work points.


Give your pins a name unique to that model, and that's it. You can provide as little or as much detail in the model as you need - the only bits that matter to the Harness module are those Pin definitions.

Once you've got all of the connectors and devices modeled, you're ready to move on to the assembly.


Place Your Parts

The next step in defining your wires and harness is to lay out your connectors and devices relative to each other in an assembly. This is just regular assembly modeling, and in fact depending on the level of detail of your model, many of the components may already be placed.


Figure 2: Control Box Assembly shown with sketched Harness Segments

Next, each component occurrence that will have wires attached to it needs to be given a unique name. This normally corresponds to the 'Tag' description on the electrical schematic, but in theory it can be any name you'd like - so long as it's unique. You apply this name as a 'Harness Property' of the occurrence, and is placed in the 'RefDes' field.


Figure 3: You can find the RefDes field in the Harness Properties Dialog.


Sketch Your Segments

The last major modeling step in the process is to sketch in the actual path of each segment of the Wire Harness. This is very easy to accomplish, as Inventor Professional allows you to freehand 3D sketch using offsets from existing faces.


Figure 4: Inventor Professional allows you to pick 3D sketch points by specifying offsets from existing faces


You can also use existing work points to sketch along - this is very useful when your harness needs to run through clips or cutouts in other parts. As you sketch, a bending radius is automatically applied, so you see an accurate representation of each harness segment.


Figure 5: Creating the new harness segment takes just 5 clicks


Wire harnesses are Adaptive by default. This is very handy when you need to re-arrange clips or components. With proper use of workpoints, your can save yourself a lot of time when those inevitable changes start rolling in.

That's it for model creation - everything else is either automatic, or point and click.


Adding Wires

So now you've got pins to run wires from and to, and you've got harness segments to run them through. How do you add the wires and run them through the harness? You can accomplish this in two ways. One is a manual process that you can accomplish solely within Inventor. The second is a very slick and automatic process that requires the use of either AutoCAD Electrical, or a little work with a text editor.


Wrangling Your Wires Manually

Placing wires manually couldn't be easier - simply choose the type of wire you want to run, and then choose the two pins connected by the wire.


Figure 6: Wires can be added with 3 clicks

Inventor Professional will add a single straight line segment to the model that connects the two pins, and it will have the color corresponding to the type of wire. Pro ships with an extensive definition of wires, so for most work you probably won’t have to add any wire definitions. If you need to add a few, they can be added one at a time though the Cable and Harness library. If you need to add dozens, you can import them all at once using a specified format.


Automatic Wire Addition

This is where things start to get really neat. If you have a list of information about your wires - namely the pin and device they start from, the pin and device they run to, and the type of wires they are - the Harness Module can place all of your wires automatically. Like I mentioned above, you can generate this list manually using a text editor, but if you have a schematic created in AutoCAD Electrical, you can extract that information from the drawings to further automate the process.


Figure 7: Schematic representation of the control box created in AutoCAD Electrical


There's even a special report type in AutoCAD Electrical tailored to fit the default configuration of the Inventor Professional Harness module.


Figure 8: AutoCAD Electrical makes it easy to place wires in Inventor Professional


Once you’ve got your wire list exported from AutoCAD Electrical, you’re ready to run the wires. Tell Pro how your wire list is configured (through a .cfg file), tell it where your wire list is, and then let it go to work. After a few seconds, you’ll see all your wires have been run from pin to pin.


Figure 9: Wires imported from AutoCAD Electrical


It’s important to note that while helpful, having AutoCAD Electrical is not required. You can generate lists of wires manually and import them in the same fashion, you just need to stick to a format and tell Inventor Professional what that format is.


Wrangling Those Rascals

Great, so we have all of our wires in the model now. But what a mess! Which wires need to run through which harness segments? How big should each segment be? No worries – as with everything else up to this point, Professional will do all the work for us if we’d like.


Figure 10: Automatic Routing optimizes the process and never misses a wire

Not only will Pro make sure all the wires run through the harness in the most efficient manner, but it will even size the harness based on the number and size of wires running through each segment.


Figure 11: You can let Pro size your harness, or specify your own diameter if you need to leave room for un-modeled wires.

That’s it for the model creation process. We now have an adaptive, but more importantly an intelligent model of our wires and harness. Next month I’ll show you how Inventor Professional will help you document your new creation, making the build process much more efficient.