Capital

Harness Designer Modular Introduction

In electrical system design, customers face the challenge of striking a balance between offering a wide range of products and product options, while managing the many different electrical configurations needed to support the product range.

One solution to this challenge is the use of composite harnesses. A composite harness is a (typically virtual) superset that collates all variants of a harness in one container—the composite harness.

Capital Harness Designer can depict a composite harness and automatically generate the details of every variant of it as, and when, required. This is achieved using Option Expressions on wires and components representing the product features needed in each variant. Derivative Harnesses or, as they are commonly termed, “derivatives” are generated through the process of Composite Breakdown. Each derivative represents a fully functional variant of the composite harness that contains a subset of its content.

Variant management problems can sometimes arise using this approach. For each optional feature added to a harness, the number of variants is doubled, and increasing the number of variants means increasing the system resource overhead of managing their associated part numbers and option associations.

Capital Harness Designer Modular enables harnesses to be designed and constructed from a series of sub-modules, which correspond to either a vehicle function or manufacturing process. Modular harness design techniques address the overhead of variant management experienced in derivatives and reduce the overhead of variant management for highly variable harnesses.

A composite superset describing all variants of a harness is still used, but instead of breaking this down to finished versions (derivatives), it is broken down into partly-finished Modules. In isolation, modules are not complete fully-functioning harnesses, but sub-assemblies that correspond to partial vehicle functions. These sub-assemblies are assembled together as, and when, required to form the final completed harness.

A (functional) module normally has a one-to-one relationship with its corresponding function, while derivative may have a number of "applicable options” associated with it. Utilizing the modular harness design process significantly reduces the system overhead of managing harness variants. It does this by transforming the problem of managing complex derivative combinations based on option content into one of managing simple modules.

The differences between using derivative and modular designs can be illustrated using the following scenario. In this example, two optional vehicle functions are available:

• Option A: Electric Windows

• Option B: Heated Seats

Taking a derivative approach, all combinations of the three options are calculated, resulting in four derivatives that need to be managed:

Option A	Option B	Derivative
No	No	D1 (Base: no optional features present)
No	Yes	D2 (Heated seats)
Yes	No	D3 (Electric Windows)
Yes	Yes	D4 (Heated Seats and Electric Windows)

This means that four derivatives are needed for a given set of options. In contrast, in a modular approach, there would only be two modules to manage, one corresponding to each function:

• Module A: Electric Windows

• Module B: Heated Seats

By having these two modules available “off the shelf,” ready for usage, once a certain configuration is determined, the modules needed to complete the harness (Module A or Module B) can be assembled on the spot into the harness. As the number of harness options and functions increase, the reduction in variant management overhead using a modular approach becomes more apparent.

Parent Topic:

Capital Harness Designer Modular

Capital Harness Designer User Guide, 2512

Unpublished work. © 2025 Siemens