110 pounds of wiring.

That is, in total, the estimated amount of wiring in the Bentley Bentayga, one of their latest luxury SUV offerings. On the surface, that alone might seem like a lot. Yet, when you consider what systems those wiring systems support, I’m actually surprised it isn’t more.

Almost as much as fuel, electronic signals are the lifeblood of a modern vehicle. And the Bentley ­Bentayga is a poster child for just how complex today’s electrical systems can be. If it doesn’t have the most-elaborate wiring in the civilian ground-bound vehicular world, it’s close. The Bentayga offers four long-range radar systems, up to 12 short-range ultrasonic parking sensors, six camera systems, dozens of lighting ­elements, a 48-volt roll-control suspension system, a champagne fridge, an 18-speaker stereo, a watch winder, and seats that can warm, cool, and massage occupants. And all of it is designed to withstand heat, cold, dust, moisture, and electromagnetic interference.

It Takes a Lot of Wiring to Keep a Modern Vehicle Moving (Witness This Bentley’s Harness), Car and Driver, June 2016

Look what our demand for smart connected products have wrought.

Like never before, electrical systems in all kinds of products are more complex than ever. While the weight of the wiring system alone is intimidating, the amount of connectivity between all the sensors and control units is even more staggering. The sheer amount of signals running back and forth in these systems is overwhelming. Yet, they are designed and delivered on shorter schedules than ever.

Now, some twenty years ago, the tools available to design wiring systems were capable. You developed a schematic. Then you moved on to the diagram. Then you routed the wires, coupling them into bundles, through the 3D MCAD assembly. Now, think about trying to use those tools in to design these modern systems. You have an entire automotive platform with countless variants, each with various systems as options. Simply put, that old-school set of digital design tools won’t keep it. It would be overtaken with complexity in little time.

That’s the context in which I set out to understand what the Capital Platform of products from Mentor, which is now a division of Siemens PLM, could offer. That’s the focus of this post. As you’ll find, there is a lot of capabilities spread across a lot of products that belong to this modular platform. But what’s even more interesting is the characteristics of the platform overall. But I’m getting ahead of myself here. Let’s start with the products.

Capabilities of Products in the Capital Platform

There’s a lot to unpack here. In this post, I’ll be focusing on the six products in this platform that relate to system design and detailed harness design. Yes. That means there is a lot more. Those other products focus on manufacturing process planning, work instructions, services instructions and a lot more. But here, let’s focus on design.

Capital System Capture

For all intents and purposes, this product looks, feels and acts like a traditional system engineering tool. You can start with requirements, develop functions and systems of functions as well as allocate requirements to those functions. Instead of this product, you actually can use other similar system engineering technologies. However, there are some advantages of staying within the platform. We’ll get to that when we talk about the platform overall below. But know this: it offers the capabilities you need to define an overall electrical system functionally.

Capital System Architect

This product right here, this is where it gets interesting.

Ultimately, the purpose of this product is to go from a set of functions to developing a logical architecture of your electrical system. It provides some unusual key capabilities, which include:

  • The input here is a set of functions you defined.
  • You can develop different candidates for your electrical architecture by selecting different electrical components like ECUs, developing your nets and assigning signals. You assign different functions from your system design to these different aspects of that architecture.
  • You capture these candidates as different baselines. Those baselines are saved and you can revisit them as you need to do so, tinkering along the way.
  • In parallel with developing the architectural candidates, you define what measures or metrics are most important. This might be network bandwidth, showing you how much is taken up by your system’s signals as you add more to certain nets. It could be CPU utilization within an ECU as you assign more functions to it. The product offers a number of these metrics out of the box, but you can define your own as well. Note that these measures are updated live, so as you change a candidate architecture, the metrics tracking those measures update in real time.
  • You can then compare and contrast your different candidate architectures against one another. There is a handy spider chart that shows how each performs against the metrics that matter to you.
  • You can also define design rule checks, as well as use a large set of out-of-the-box ones, against which you need to comply.

All of this sets you up to do trade studies to figure out which candidate architecture is the best for your product platform. You can see what happens to your metrics when you move a function from one ECU to another. Simultaneously, you can watch how your network loads change as well. In all, you can work through all the options to determine which logical architecture is best for your constraints.

With that done, you’re ready to move on to the detailed design of your electrical system, which is where you’ll start defining wires and determining which signals go on what wires and whatnot. But as you’ll find out, you can choose between two different workflows at this point.

Capital Devices

This product allows component engineers to create and edit the information about electrical components. All this work is part of the central platform, so change can be managed across all of the electrical systems that are in all those product platforms. More about the implications of that in a moment.

Capital Logic

This product is the most widely proliferated amongst Capital customers. This represents the manual design approach for the first part of wiring design. You start with the logical architecture of your electrical system and create detailed schematics for which wires connect between which electronics and carry which signals.

After all that detailed work is completed, the harness design starts. All this connection information is exported out to an MCAD application where those wires can be bundled together and routed through the 3D assembly. The characteristics of the harness generated there returns back into the platform through Capital HarnessXC. We’ll get to that soon.

Capital Integrator

The alternative to the manual process in Capital Logic is an automated process called Generative Design. Now, if you’re familiar with Generative Design from the MCAD world, note that this is very different. This does not generate hundreds or thousands of alternatives of your wiring design. Instead, it automatically creates a single design. But notably, it does it automatically for an entire product platform, creating different wiring designs for different variants. In the following process, though, you have a lot of control over the outcome.

  1. Electrical System Architecture: Remember the logical design you developed in Capital System Architect where you went through the trade studies? You use it here. Again, this shows what electronics fulfill which functions in the system.
  2. Electrical Variation: If you have options and alternates as part of your product platform, this product takes that into account. That will, of course, result in variants of your wiring design.
  3. Design Rules: Every design effort is constrained. In some areas of your product, like an engine compartment, you can’t have splices. When you have specific types of control units, you want all wires terminating to it to be green or red. Sometimes, in redundant systems, you have to completely replicate signals between the same two electrical components. You capture all that here because the product will generate your harness based on those constraints.

This product automatically and independently creates the wiring design with assigned signals based on these inputs.

Once that is done, harness design starts, just as it does with Capital Logic. You export all this connectivity information to your MCAD application to route your wires and create bundles through the 3D assembly.

Routing in Your MCAD Application

No. This isn’t part of the Capital platform. But it is important to note that getting information out to an MCAD application and routing your harnesses through the 3D assembly is a step on the critical path of this process. To be clear, you don’t route your harness in Capital. When you’re done in your MCAD application, you bring the information generated there like the bundle structure with exact breakout locations, wire lengths and bend radii back into the Capital Platform using…

Capital HarnessXC

Using documented interfaces, this product exchanges information with almost all major MCAD applications out there. It brings in all the physical information about your wires and harnesses like lengths and bend radii together with wiring information from Capital Logic or Capital Integrator. You can perform design rule checks here, but there is likely some capability for that regarding physical characteristics in your MCAD application.

From a system and detailed design perspective, that completes the process. Believe me, there’s a lot more capability in the rest of the platform regarding manufacturability, estimating costs, transforming the Bill of Materials (BOM) into a mBOM and much more. But we’re going to keep this focus on the design aspects.

Now, let’s talk about the platform.

Characteristics of the Capital Platform

When you look at the products in the Capital Platform, there are some really interesting capabilities that are offered. However, there are just as many interesting things about the Capital offering as a platform.

Database Driven, Not Cloud-Based

Throughout this post, I have specifically use the term platform instead of a suite. While a software suite often has tight integration, a platform of product works off a single source of the same underlying data. And that applies to the Capital offering.

This platform is database-driven. It uses a client-server architecture with the database and data server hosted in an on-premise data center or virtualized in the cloud. Most of the clients here are installed software applications. Yet, a few are browser-based, like Capital Devices. Overall, note that this platform is not a cloud-based offering. There is no multi-tenant subscription-based solution here. Perhaps there could be someday, but not now.

So, why is this a big deal? Well, there are a few reasons.

  • Any database-driven platform alleviates the need to manage files. And as I have mentioned in other blog posts, managing files can be a source of painful errors. Emailing them around means users can work against outdated information. Merging changes from many different stakeholders is difficult. There are few ways to share files in an IP-friendly way with external participants. There are lots of problems with file-based solutions.
  • In the context of Capital, this particular database-driven offering was specifically developed to know and understand the concepts of electrical system design. It understands what a wire is, so when you draw two of them merging, this platform knows that is a splice. It understands what a signal is, so when you draw those coming together, it knows that is a junction. Having that context allows the system to intelligently and automatically create and classify correct actions without user intervention. It eliminates errors.
  • The knowledge of this platform extends further. It also understands the transformative nature of electrical system design. It knows the progression is from requirements to functional design to logical design to physical design. So when a function is assigned to two control units, the platform understand that two electrical components will need to communicate using a signal on a net. That, by itself, offers some advantages:
    • This provides traceability to manage change. With traceable connections back and forth, you can understand the impact of a change. Thinking about changing that requirement? Capital will show you a list of the functions, components, and wires that are affected. Thinking of changing that wire? It will show you the list of associated things, all the way back to the original requirement, that will be affected.
    • The platform supports the next step in the process. Because it knows what each thing at each step of the design process is, and it knows where you are with respect to those steps, it knows what you need to do next. It can automate the process as well as check your design for completeness.

All of this is great with respect to design and engineering for electrical systems, but it also enables an enterprise level effort as well.

Model-Based Enterprise Approach

This isn’t the kind of MBE initiative that is commonly discussed for mechanical hardware. However, there are a lot of similarities.

The idea here is that downstream participants all view and reference a single source of the truth, a model of the design, instead of derived documentation representations. More specifically, anyone from sourcing, manufacturing, service and a myriad of other departments can view the model of the electrical system in Capital instead of 2D drawings that have been printed off or exported as a PDF. The advantage here is twofold:

  1. Any representation that doesn’t have a real-time connection to the source of truth is at risk of being out of date. It is as simple as that. That is the source of errors and the cause of many product development failures. Viewing and referencing the source material for the electrical system eliminates that chance.
  2. Other departments will need to develop their own deliverables that need to be directly derived from these design representations. Manufacturing needs to create nailboard layouts, mBoms and work instructions. Sourcing will need procurement BOMs. Service needs maintenance instructions. If the original design changes, that modification needs to flow, as appropriate to these other deliverables. That is far easier, and even automated, in a model-based approach.

Interestingly enough, I believe that the development of electrical systems is in greater need of a model-based approach than mechanical hardware. With a mechanical design, you only have a single representation, the 3D model. With harness engineering, you have many representations including functional, logical and physical. If you are exporting PDFs of those three different things, you risk of looking at outdated information is tripled.

Note that in the context of a platform offering, a model-based approach is easier. Quite literally, there are no files to get mixed up, which can happen even if you do have everything under the configuration control of a PDM system. All you reference is the model in the platform.


Another interesting characteristic of the system is the acknowledgment that the Capital platform does not have to be used as a single monolithic solution. If you need to use a different system design tool, that’s fine. You can import its work into Capital System Architect. Want to use a different detailed design tool instead of Capital Logical. That works as well. Overall, this platform was specifically architected so it can be integrated with the wider enterprise.

Notables and Final Thoughts

So, what stands out to me? There are a few things.

  • Capital System Architect: The ability to create candidate architectures of your logical design is unusual but completely valuable. This, combined with the ability to assess those candidates against key metrics is big.
  • Capital Integrator: Programmatically generating the wiring design can be incredibly helpful. Today’s engineers are overloaded, yet working against shorter schedules. Automating this aspect of the design adds a lot of value. Capturing this kind of intellectual property codifies good design practices and eases the transfer of knowledge to newly hired engineers.
  • An Electronics Aware Database-Driven Platform: With today’s level of complexity in electrical systems, this is a big advantage. The intelligence such a platform can offer delivers value to engineers by enabling them to avoid errors and saves them time by automating their tasks. Doing this through a central platform also enables broader analysis across variants in product platforms. This is also a key aspect to enabling a model-based enterprise approach.

Those are my thoughts folks. I’m keen to hear yours. Weigh in below in the comments.