How Do You Create 2 Low Speed Automotive Data Networks?

You're mid-way through validating a new vehicle subsystem. One network is handling safety-critical data, the other is tasked with body electronics. 
But somewhere between signal dropouts and unexplained EMI, it’s clear: something in the setup isn’t working. Is it the protocol configuration? The wiring? Or a missed detail in the physical layer?
These are common challenges when designing dual low-speed automotive data networks, especially as vehicles grow more complex and the pressure to deliver reliable communication increases. Separating networks for functions like lighting and braking is essential for reducing EMI, isolating faults, and complying with safety standards.
In this guide, you will learn how to properly design and implement two low-speed networks using protocols like CAN and LIN. We will walk you through topology choices, EMI mitigation, redundancy planning, and validation techniques using Keysight tools, so you can build systems that are stable, testable, and ready for the road.

Low-speed automotive data networks are designed to handle communication between electronic components that don’t require high-speed data transfer. These include systems like power windows, climate control, seat adjustment, and interior lighting. 
While these functions aren’t as time-sensitive as engine or braking systems, they still need to communicate reliably and efficiently within the vehicle’s overall architecture.
Most modern vehicles use a combination of high-speed and low-speed networks to separate mission-critical systems from secondary functions. This segmentation reduces data congestion, helps isolate faults, and simplifies compliance with safety and performance regulations. 
Low-speed networks also reduce wiring complexity and power consumption, especially important in electric vehicles where efficiency is key.
Signal quality is still critical, even at lower speeds. Engineers must account for signal integrity issues that can arise from poor cabling, grounding, or EMI. Understanding how data signals behave is essential for proper debugging and validation, something tools like oscilloscopes are built to analyze.
Whether you are designing for a luxury sedan or a compact EV, low-speed networks are a fundamental part of the system and they require just as much engineering care as their high-speed counterparts.

Three of the most widely used protocols for low-speed automotive communication are LIN, CAN, and FlexRay (in its low-speed configurations). Each has its strengths depending on system requirements.

• LIN (Local Interconnect Network) is often used for simple, single-master applications like seat motors or interior lighting.
• CAN (Controller Area Network) offers more robust error checking and is used in both low- and high-speed applications.
• FlexRay, while typically associated with high-speed applications, also supports fault-tolerant low-speed configurations in some specialized systems.

These protocols are essential for coordinating distributed ECUs and minimizing wiring harness complexity.

To properly capture, analyze, and troubleshoot these protocols, engineers often rely on automotive oscilloscopes that are specifically designed for vehicle bus decoding and validation.

In a typical vehicle, systems like braking and steering need a different level of reliability than features like seat warmers or ambient lighting. That’s why engineers often design two separate low-speed networks, each optimized for its specific role.

Why two networks instead of one?

• System segmentation
  Separating safety-critical functions (e.g., braking, airbag deployment) from non-critical systems (e.g., infotainment, lighting) ensures that a fault in one area doesn’t impact vital operations.
• Reduced data congestion
  Splitting the load across two buses prevents delays and maintains timing integrity, especially when devices share a communication channel.
• Lower EMI risk
  Dual networks allow more targeted EMI shielding and layout design, critical for avoiding RF interference that can degrade signal quality.
• Regulatory compliance
  Standards like ISO 26262 often require clear boundaries between critical and non-critical systems. Dual networks simplify documentation and testing during certification.

Use of a network analyzer during design helps engineers verify communication flow, validate topology, and catch issues before integration. The result? More stable, efficient, and compliant vehicle networks.

Your physical layer and topology decisions directly impact performance, EMI resistance, and long-term reliability. Here are key options to consider:

• Bus topology: Simple and cost-effective. Common in CAN and LIN networks but less fault-tolerant.
• Star topology: Offers better fault isolation and EMI control. More wiring is required.
• Shielded cables: Essential for EMI-sensitive environments. Adds cost and complexity but improves signal integrity.
• Unshielded cables: Lighter and cheaper. Acceptable in non-critical areas with minimal interference.
• Single-wire setups: Space-saving and economical. Best for short distances and low-noise environments.
• Twisted pair wiring: Reduces attenuation and external interference. Standard for CAN networks.

Choosing the right combination depends on the function, location, and required resilience of each network branch.

Designing and implementing two separate low-speed networks is a strategic process that improves reliability, simplifies troubleshooting, and ensures compliance across vehicle systems. 
The goal is to build two networks that operate independently but cohesively, handling different tasks without interfering with each other. One network might manage safety-critical functions like airbags or braking (requiring robust protocols like CAN), while the other handles body electronics or infotainment (where LIN may be more appropriate).
A structured approach is essential to reduce errors and speed up integration. This includes careful planning of node communication, validating performance under load, and selecting the right tools—like Keysight’s automotive oscilloscopes—to test, debug, and fine-tune the networks during development.
The following step-by-step guide outlines the critical stages in building dual low-speed automotive networks, from defining data needs to validating the final setup.

1. Identify network requirements
   Define what each network will support—e.g., safety-critical systems vs. body control modules. Document speed, latency, and reliability needs.
2. Select communication protocols
   Choose based on function and system complexity. CAN is ideal for mission-critical tasks; LIN suits simpler, cost-sensitive modules.
3. Design network topology
   Pick a layout that balances performance and cost. Use star or bus topologies, or a hybrid if needed for spatial constraints.
4. Implement EMI shielding and filtering
   Integrate shielding and grounding strategies early. Follow EMI compliance standards to reduce cross-talk and radio frequency interference.
5. Validate with simulation tools
   Before deployment, simulate real-world conditions and test robustness using tools like a spectrum analyzer to identify signal noise or protocol issues.

Each step builds toward a network that’s resilient, compliant, and ready for production environments.

Electromagnetic interference (EMI) is a major threat to the reliability of low-speed automotive networks. Even though these networks operate at lower data rates, they are often more vulnerable to noise due to simpler physical layers, longer wire runs, and proximity to high-power components like motors, relays, and power electronics.
If left unmanaged, EMI can cause signal distortion, data corruption, and communication failures, especially in systems that must function consistently, like door locks, lighting, or HVAC controls. In worst-case scenarios, EMI can trigger false signals or disrupt safety-critical subsystems if the networks are not properly isolated.
Mitigating EMI requires both proactive design strategies and real-time testing. Engineers must incorporate shielding, grounding, and layout optimization during the physical layer design. Later, signal quality can be assessed using digital signal processing techniques to identify anomalies, and band-stop filters to eliminate noise from specific frequency ranges.
Pre-deployment testing with tools like spectrum analyzers ensures your network is resilient to the real-world EMI it will encounter on the road.

The following table compares common EMI mitigation methods used in low-speed automotive data networks.

Combining multiple techniques provides the best results, especially in complex network environments with mixed data speeds and high-voltage systems.

In automotive systems, communication failures aren’t just inconvenient—they can be dangerous. That’s why network redundancy and fault tolerance are essential when designing dual low-speed data networks. Redundancy ensures that if one communication path fails, another is ready to take over without compromising performance or safety.
Redundant networks are especially critical for safety-related functions like braking, power steering, or airbag deployment. In these scenarios, even a brief communication loss can have serious consequences. By duplicating communication channels and implementing fault detection logic, engineers can create systems that recover automatically from disruptions.
Fault tolerance also improves vehicle uptime. Instead of forcing a full system reboot after an error, a fault-tolerant network isolates the issue and continues operating—often with degraded performance, but still safely. These features are supported through logic-based control systems, including logic gates that detect and respond to anomalies in signal flow.
When redundancy is baked into the design, it reduces warranty claims, increases customer satisfaction, and ensures that vehicles meet stringent functional safety standards like ISO 26262.

Before dual low-speed automotive networks can go into production, they must be rigorously tested. Pre-deployment validation is essential for ensuring signal stability, protocol compliance, and EMI resilience, all of which affect vehicle safety and reliability.
If left unchecked, signal issues can lead to intermittent communication failures, delayed responses, or complete subsystem shutdowns. EMI, improper grounding, or a flawed network layout can all contribute to these failures. That’s why engineers rely on advanced tools to monitor waveforms, trigger on anomalies, and decode messages in real time using features like oscilloscope triggering and waveform analysis.
Validation also helps ensure compliance with industry standards. CAN networks must meet ISO 11898, while LIN follows ISO 17987. For EMI compliance, IEC 61967 defines how emissions are measured. Meeting these standards is not optional, especially in systems tied to vehicle safety.
More importantly, thorough testing reduces the risk of system failures in the field, where diagnosing issues becomes exponentially harder and more expensive. With pre-deployment validation, engineers can simulate real-world conditions, spot early warning signs, and optimize designs before mass production begins.
The bottom line: testing isn’t just a quality check, it’s a strategic investment that protects your product, your timeline, and your end user.

To validate low-speed networks effectively, engineers need purpose-built tools. Each tool provides unique insights into signal behavior, protocol accuracy, and physical layer health.

For more tips on choosing the right tools, see our used oscilloscope buying guide.

When validating dual low-speed networks, engineers must evaluate specific performance metrics that directly impact functionality and reliability:

• Signal integrity: Ensures voltage levels, rise times, and pulse widths fall within specification. Poor signal integrity leads to misreads or communication loss.
• Timing accuracy: Checks that signals are synchronized correctly, especially for time-sensitive CAN traffic.
• Protocol compliance: Confirms message IDs, lengths, and CRCs align with CAN/LIN standards. Inconsistent messages may indicate software or hardware errors.
• Oscilloscope frequency response: Determines how well the scope can capture relevant signal bandwidth. A higher bandwidth oscilloscope reveals faster glitches and signal anomalies.
• EMI susceptibility: Measures how well the network withstands external interference, using controlled RF exposure and spectrum analysis.

Failure to meet these benchmarks can cause in-vehicle communication failures, recall risks, and regulatory delays. Reliable testing ensures the network performs under all conditions before reaching the road.

Automotive communication networks must meet strict regulatory standards to ensure safety, interoperability, and electromagnetic compatibility. For low-speed networks, the most relevant standards include:

• ISO 11898: Specifies CAN communication, including physical layer, data link, and error handling.
• ISO 17987: Defines the LIN protocol, including frame formats and scheduling.
• IEC 61967: Covers EMC testing for integrated circuits and systems, critical for verifying EMI performance.

Certification to these standards ensures that your network design meets industry benchmarks for robustness and reliability. It also demonstrates regulatory readiness, an important requirement for OEMs and Tier 1 suppliers.
Failing to comply can lead to project delays, certification failures, or in-field defects. Validating against these standards early reduces risk and accelerates your path to production.

Cost is always a significant factor in designing low-speed automotive data networks. OEMs face the challenge of balancing cost-effective solutions with the reliability and performance that modern vehicles demand. 
OEMs have to decide where they can afford to compromise and where they can’t. For instance, protocols like CAN provide robustness and reliability, but the initial setup cost is higher than simpler solutions like LIN. Similarly, more advanced topologies and network redundancies come with additional costs in terms of hardware, installation, and testing.
With rising production costs and increasing pressure to meet deadlines, discounts and efficient use of resources have become more important than ever. 
As Marshall Kay, an account manager at Keysight, points out, "Budgets are under pressure nowadays. 500k for a product can be a lot of money, discounts are very appreciated." OEMs must balance their financial constraints with the need for a robust, safe, and future-proof design.

When choosing between different network solutions, OEMs must consider both the cost and performance to ensure optimal system functionality and profitability.

While higher performance options like FlexRay come with increased costs, CAN and LIN offer reliable, cost-effective alternatives for many standard automotive functions.

The Total Cost of Ownership (TCO) is not just about the initial hardware cost, it also includes ongoing expenses like maintenance, testing, compliance checks, and security upgrades. These hidden costs can accumulate over the vehicle’s lifecycle, making it essential to consider the long-term impact of design decisions.

Upfront savings can often be outweighed by hidden costs in the future, so engineers should focus on long-term reliability and ease of maintenance to reduce the total cost of ownership.

OEMs can achieve a balance between cost-saving and performance by employing several strategies during the design phase. Some key approaches include:

1. Reusing components: Maximize the use of common parts across the vehicle’s various networks.
2. Reducing wiring complexity: Use integrated components and optimize layouts to minimize cable runs.
3. Selecting cost-effective shielding materials: Choose appropriate EMI protection that balances cost with performance.
4. Choosing modular systems: Use scalable designs that can be adapted for different vehicle models.

By strategically selecting components and minimizing unnecessary complexity, OEMs can reduce upfront costs while still meeting reliability standards.

Wired and wireless solutions each come with distinct cost implications. Wired networks like CAN and LIN are typically more cost-effective because they have lower hardware and installation costs. However, they require physical connections and more complex wiring, which can increase installation time and labor costs.
On the other hand, wireless solutions (e.g., BLE, Zigbee) offer flexibility and reduced physical complexity, but costs related to signal reliability and interference management can increase, especially in environments with high EMI.

OEMs typically choose wired solutions for cost-sensitive, short-range applications, while wireless options are selected for flexibility in non-critical systems.

When working within tight budgets, engineers must balance cost with reliability. This often involves prioritizing the most essential features while minimizing unnecessary expenditures.
Key factors to consider when working within budget constraints include:

• Protocol selection: Opt for cost-effective solutions like LIN for non-critical systems.
• Topology: Simplify wiring to reduce material costs and installation time.
• Redundancy: Consider lower-cost fault tolerance mechanisms that don’t compromise safety.
• Component reusability: Reuse network components across different vehicle models and systems.

Large OEMs and startups often approach these constraints differently. Startups may prioritize lean designs and focus on cost-efficient scaling, while larger OEMs can invest more in redundancy and future-proofing, allowing for greater flexibility in design choices.

The evolution of automotive data networks is being driven by the increasing complexity of modern vehicles, the push for higher safety standards, and the demand for enhanced connectivity. 
As automotive systems become more interconnected, the traditional, rigid network designs are being replaced by software-defined networking (SDN), a shift that offers greater flexibility, scalability, and adaptability in how vehicles communicate.
With SDN, automotive manufacturers can implement dynamic network configurations that can be adjusted in real-time, enabling faster updates, better fault isolation, and more efficient use of available bandwidth. This is particularly valuable for systems like infotainment, lighting, or climate control, where performance requirements may change over time based on user preferences or regulatory updates.
Additionally, AI-driven diagnostics and predictive maintenance are changing how low-speed networks are monitored and maintained. By leveraging machine learning algorithms to analyze data in real-time, manufacturers can proactively detect issues before they cause failures, reducing downtime, minimizing repair costs, and enhancing vehicle reliability. AI can also optimize network performance by identifying patterns in network traffic and adjusting configurations to avoid congestion or delays.
As these technologies continue to evolve, network testing and validation become even more crucial. Engineers will need tools that can simulate complex network conditions, ensuring reliability and compliance with future standards. 

Designing dual low-speed automotive data networks is crucial for ensuring reliability, safety, and efficiency in modern vehicles. By focusing on protocol selection, EMI mitigation, and fault tolerance, engineers can build robust networks that meet both current needs and future demands.
As the industry shifts toward software-defined networking (SDN) and AI-driven diagnostics, automotive networks are becoming more flexible and adaptive. Engineers must stay ahead by leveraging advanced testing and validation tools to ensure their designs are future-proof.
Keysight’s innovative solutions provide the tools necessary to optimize network performance and ensure compliance with industry standards. Ready to take your automotive network design to the next level? Explore our cutting-edge tools and start building smarter, more reliable systems today.

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