To thrive, the industrial world depends on reliability. For decades, serial communication has been a cornerstone of operational technology (OT), ensuring seamless connectivity across factory floors, power grids, and transportation systems. But in today's increasingly interconnected industrial landscape, where innovation accelerates at an unprecedented pace and cyberthreats loom larger than ever, how can businesses ensure their legacy serial infrastructure remains secure and relevant?

To find the answer, we must connect legacy systems with innovative solutions, seamlessly combining the reliability of serial systems with the benefits of modern technology and robust cybersecurity. This involves not just maintaining the core functionalities that have driven industrial success for years but also adapting to the digital world’s increasing demands. This article gives a step-by-step plan to modernize and secure your serial communication infrastructure for reliable operation without costly disruptions.

The Evolving Landscape of Serial Communication

Serial communication remains a foundational technology in many industrial settings. Its simplicity, flexibility, and cost-effectiveness make it indispensable for connecting a wide range of industrial devices, ranging from sensors and actuators to PLCs and HMIs. Consider the widespread use of serial devices in factory automation, with RS-485 networks enabling communication between many devices across large factory floors. Think also of serial communication’s crucial part in power grids: it ensures reliable monitoring and control of remote terminal units (RTUs) across vast distances.

However, maintaining, integrating, and securing this critical infrastructure in an era of rapid technological change presents unique challenges. With the rise of the Industrial Internet of Things (IIoT) and Industry 4.0, serial communication needs to work alongside newer technologies such as Ethernet, wireless, and cloud computing. This convergence brings opportunities for enhanced efficiency and data-driven insights while also introducing complexities in interoperability and security. Several key questions arise:

1. How can you guarantee the long-term availability of the solutions you depend on, given supply-chain issues and aging components? 
2. How can you ensure your legacy systems remain compatible with new technologies? 
3. How do you protect your serial communication networks from increasingly sophisticated cyberattacks that can disrupt operations, compromise data integrity, and even cause physical damage?

Bridging the Gap: Three Commitments to Secure Serial Communication

Navigating the future of OT requires a strategic approach to serial connectivity. When evaluating solutions, consider these core commitments:

1. Ensure Long-term Operational Reliability:

To avoid costly disruptions and maintain operational efficiency, long-term support of your existing serial infrastructure is crucial. This is more than just having access to spare components and repairs. A proactive strategy for life-cycle management is necessary to preempt and minimize the risks of components becoming obsolete.

A single component’s unavailability may not cause an immediate system shutdown; however, the long-term implications of shortages and obsolescence are substantial. The consequences include increased costs for parts, longer repair times, higher counterfeit part risks, and the necessity of expensive, disruptive upgrades to the entire system—or competitive failure.

Therefore, it is critical to choose a solution provider that demonstrates a strong commitment to long-term support and proactive life-cycle management. Look for vendors that offer:

• Solutions built on modern, adaptable platforms: This ensures that the underlying technology is less likely to become obsolete quickly.
• Readily available components: Prioritize vendors offering components with reliable supply chains and long lifespans.
• Updatable firmware: Regular firmware updates provide security, compatibility with evolving standards, and new features.
• Transparent lifecycle policies: Vendors must clearly communicate their product life-cycle plans, including end-of-life (EOL) timelines and migration strategies.
• Proactive obsolescence management: Continuously monitoring components' availability, identifying risks of obsolescence early on, and communicating mitigation options to customers in advance.
• Alternative solutions: If products or components become unavailable, the vendor must provide smooth transitions to alternative solutions.

The rapid pace of technological change in the semiconductor industry makes this a critical consideration. Choosing a partner with a proven track record of long-term supply stability and a proactive approach to obsolescence management is crucial for minimizing risk and maximizing the lifespan of your serial communication infrastructure. 

2. Embrace Modernization and Interoperability:

Constant innovation drives the ever-changing industrial landscape. Your serial communication technology needs to keep up. Therefore, to ensure seamless communication with today’s systems and digital infrastructure, support for traditional serial protocols (like Modbus RTU) and modern Ethernet protocols (like Modbus TCP/IP, PROFINET, EtherCAT) is required.

To succeed, prioritize solutions promoting this integration. For example, advanced serial device servers or protocol gateways should offer flexible configuration options for easy serial-to-Ethernet connectivity and secure data transmission to cloud applications. Additionally, incorporating eco-friendly materials, energy-efficient architectures, and extended product life cycles aligns with global Environmental, Social, and Governance (ESG) commitments, ensuring that industrial connectivity solutions contribute to sustainability goals. By using this approach, you can use data analytics and digital transformation to increase the value of your current serial investments. 

3. Prioritize Robust Cybersecurity:

Cyberattacks on industrial systems are growing in both frequency and sophistication. Attacks can range from opportunistic malware to targeted intrusions designed to disrupt operations, steal data, or even inflict physical damage.

Don’t just rely on broad standards—demand concrete security features. Modern secure serial connectivity solutions should offer:

• Device-level Security and Event Logging: In contrast to older, less secure serial devices, modern solutions use detailed event logs to monitor unauthorized access, restarts, configuration changes, and other suspicious activity. This provides crucial visibility into potential threats targeting your serial infrastructure.
• Strong Authentication: Unlike legacy systems that often lacked authentication, modern converters require strong passwords and user authentication to prevent unauthorized access, even at the edge of the network.
• Data Encryption: To protect against eavesdropping and ensure data confidentiality, and to meet requirements like those in the Cybersecurity and Infrastructure Security Agency (CISA) guidelines, encrypt data transmitted from serial devices using protocols like TLS/SSL.
• Role-based Access Control: Restrict user actions based on their roles. For example, limiting an operator to read-only access while granting an administrator full control reduces the risk of compromised credentials. This represents a major change from older systems, which often lacked access control.
• Secure Firmware Updates: Regular, secure firmware updates are essential to patch vulnerabilities. Ensure your solutions provide a mechanism for secure and authenticated firmware updates, protecting against the latest threats and meeting the ongoing vulnerability management requirements of standards like IEC 62443.
• Integration With IT Security Infrastructure: Modern OT security often requires integration with existing IT security systems, including centralized authentication systems like RADIUS and LDAP.

These features, aligned with standards like IEC 62443-4-2, are no longer optional; they are essential for protecting your operations and ensuring compliance.

Real-world Example: Securing Critical Infrastructure

Let’s explore the case of a natural gas pipeline operator tasked with modernizing their monitoring system. The operator needed to enhance their cybersecurity posture to address evolving threats and achieve compliance with the requirements of IEC 62443-2-1, which mandates a comprehensive cybersecurity management system for asset owners. A key part of this modernization was integrating their legacy serial devices—such as gas actuators and flow meters—into the industrial Ethernet network. This integration needed to meet the overall system security requirements defined in IEC 62443-3-3, aiming for a specific Security Level (SL) appropriate for critical infrastructure.

This required deploying secure serial device servers that could provide robust protection at the field level. Moxa's NPort 6650 secure terminal servers, which are certified to IEC 62443-4-2 SL2, fulfilled this role. These devices offered a range of security features, including centralized authentication integration (streamlining identity management across the network), secure operation modes (encrypting serial-to-Ethernet traffic), and configuration checksum validation (detecting unauthorized changes). Furthermore, Moxa's commitment to continuous vulnerability management and providing security updates helped ensure long-term protection.

However, the threat landscape continues to evolve. The operator recognized that ongoing efforts are needed, including enhanced incident logging, hardware-level root-of-trust, and natively secure-by-design edge connectivity solutions, to maintain a strong security posture and meet future challenges. By adopting Moxa's solution, the pipeline operator not only took a significant step towards achieving their system's target Security Level under IEC 62443-3-3 and meeting the requirements of IEC 62443-2-1 but also preserved the reliability of its legacy serial infrastructure while preparing for future security needs.

Embracing the Future of OT

In today's rapidly evolving industrial landscape, balancing legacy systems with innovation is crucial. Choosing solutions that ensure long-tern operational reliability, embrace modernization and interoperability, and prioritize robust cybersecurity ensures your serial communication infrastructure remains secure, reliable, and ready for the future.

Ready to learn more? Download our white paper, "A New Standard for Serial Connectivity: Part I: Longevity" for an in-depth exploration of the challenges and solutions shaping the future of industrial communication.