Import Electrical Intent into Autodesk Inventor Professional

12 Feb, 2004 By: Amy Bunszel

Anyone who has ever turned on a newly designed machine only to hear a snap, crackle, or pop as a costly component is fried knows the frustration of a miswired electrical system. Equally frustrating is the opposite-you turn it on, but nothing happens. In both cases your hardware prototype is built and ready for testing, but you can't turn it on without the right electrical connections.

In this column we cover the basics of setting up a wire harness design in Autodesk Inventor Professional-a superset of Autodesk Inventor Series that includes tube, pipe, cable, and wire harness capabilities-so that you can link with electrical connectivity data coming from from/to wire lists created in Microsoft Excel or in programs such as AutoCAD Electrical. By automatically importing electrical connectivity, you ensure that the electrical intent established by the electrical designer is carried forward into the mechanical assembly so that your harnesses function and fit right the first time.

Wire List Requirements
So how do we accomplish this tricky task of merging electrical and mechanical data? First, create a one-to-one mapping from the electrical data to the mechanical assembly. The source for the electrical data can be a from/to list or an AutoCAD Electrical diagram, so let's take a look at the information we need to extract from these inputs. At a minimum, the wire list must contain the following fields (figure 1):
    Wire ID
    Wire Part Number
    Unique ID or Reference Designator for Connector 1
    Unique Pin Name on Connector 1
    Unique ID or Reference Designator for Connector 2
    Unique Pin Name on Connector 2

Figure 1. Wire lists, similar to the one above, are used to define connectivity in the 3D harness design environment in Autodesk Inventor Professional.

The Autodesk Inventor model must be prepared to receive this data. The connectors and pin names must be identified so that each instance has the same unique ID as its partner in the from/to list or on the diagram. The pin numbers are typically assigned when creating the Autodesk Inventor model for the connector based on manufacturers' data. It's also helpful to put in a placeholder for the reference designator-for example, J? or U?. This serves as a convenient reminder that the instance identifier still needs to be added to the occurrence. This way, multiple occurrences of the same connector each carry a unique identifier.

The wire part number must also match a wire in the wire library so that when you import the wire you have not only the correct electrical connections, but also the right physical wire, be it standard hookup wire, fiber optic cable, or even coax. Once you assign the color, diameter, and other manufacturer's databook properties to the library wire, all you need to do is call out the part number in the wire list to get all the data for that wire.

A unique identifier or Wire ID is also required for each wire. This assists Inventor Professional in tracking individual wires as they change on subsequent imports. Because a wire list import can be performed at any time, you don't need to import all the wires at once. You can import wires in batches that correspond to logical parts of the electrical system or physical areas of the assembly-however it's convenient to organize your work.

Considerations for AutoCAD Electrical
When you create wiring diagrams in AutoCAD Electrical, one simple command exports the from/to list format needed for Autodesk Inventor Professional. Though AutoCAD Electrical is optimized for ladder diagrams for control cabinets and PLCs, it can be easily adapted to create point-to-point wiring diagrams (figure 2).

Figure 2. Use AutoCAD Electrical to create point-to-point wiring diagrams, then save them as from/to wire lists that can be imported into Autodesk Inventor Professional.

Employ the following techniques to automatically produce the output needed for Autodesk Inventor Professional:

  • The component tags or names on the components in AutoCAD Electrical must correspond to the unique identifier or reference designator for the corresponding electrical part occurrence in the 3D harness.
  • The pin numbers on the component symbols in AutoCAD Electrical must correspond to the Pin Name property on the equivalent pin in Autodesk Inventor Professional.
  • The wire ID for each wire comes from the wire number in AutoCAD Electrical. Therefore, the wire numbers in AutoCAD Electrical must be set to Fixed so they persist as the design changes.
  • Wires are placed on Wire Layers in AutoCAD Electrical. Each Wire Layer must correspond to a valid Library Wire in Autodesk Inventor Professional.
  • The exact physical intent of each wire must be depicted in the wiring diagram, so branches and Ts in nets that represent logical connections are not valid on nets imported into Autodesk Inventor Professional. These types of representations map to multiple possible physical configurations.

Error Reporting
When Inventor Professional imports a from/to wire list, a variety of checks occur to ensure that the electrical intent is properly transferred into the 3D environment. For example, you'll know if wires can't be added because their library wire definition can't be found or the connector or pin specified does not exist. These are easy problems to fix in a 3D software model, but very expensive to fix during prototyping. Autodesk Inventor Professional alerts you to the following conditions:

  • Connectors and pins that can't be found in the Autodesk Inventor model.
  • Wire part numbers that don't appear in the wire library.
  • Wires that have changed terminations.

Wiring Wrap
Autodesk Inventor Professional enables you to easily link an electrical wiring design with the 3D mechanical assembly it powers (figure 3).

Figure 3. You can automatically add wires for the 3D harness design by importing a wire list, ensuring the accurate transfer of electrical intent into the mechanical design.

Whether you're importing a from/to wire list created with AutoCAD Electrical or another source, you'll reduce human error and improve communication between electrical and mechanical teams with this easy-to-use wire list import functionality.

About the Author: Amy Bunszel