IoT overlay or full OT system replacement: An architectural choice

Defining strategic goals for OT infrastructure modernization

The growing need for digitalization and operational optimization in physical environments compels companies to reassess their approaches to legacy OT systems. A crucial first step is clearly defining the business objectives for modernization. Typical goals include enhancing operational efficiency, reducing costs, improving security, and creating new services and capabilities. For instance, integrating digital technologies with physical operations can streamline processes, cut costs, and position companies as industry leaders. Research indicates that improved operational efficiency (60.4%) and increased employee productivity (57.1%) are among the most cited outcomes of digital investments. Modernizing legacy systems also unlocks the potential of real-time data analytics, artificial intelligence (AI) solutions, and IoT.

Analyzing the current state of legacy OT systems: Evaluation criteria

Before making an architectural decision, an objective assessment of the existing OT infrastructure is essential. Legacy systems often have limited security features, creating vulnerabilities when connected to IoT networks. Furthermore, they may present compatibility issues, scalability challenges, and high integration costs. Key evaluation criteria include:

• Age and maintainability: Legacy systems may require specialized knowledge and expensive experts for maintenance.
• Compatibility and protocols: Many older devices use proprietary communication protocols incompatible with modern IoT devices.
• Security: Older systems were often not designed with contemporary cyber threats in mind, making them vulnerable.
• Scalability: Traditional OT systems are typically inflexible and scale poorly to accommodate additional devices or data streams.
• Documentation availability: Lack of up-to-date documentation complicates integration and support.

Conducting a cybersecurity risk assessment early in an IIoT digital transformation project is critical for informing system design. This process involves defining the system under assessment, identifying the consequences of unauthorized access, listing known vulnerabilities, identifying threats, and estimating their likelihood. Standards such as ISA/IEC 62443 provide frameworks for risk assessment and developing security architectures for OT systems.

IoT overlay: Advantages, disadvantages, and application scenarios

An IoT overlay involves adding a new technological layer to existing legacy OT systems to collect data and extend functionality without completely replacing them. This approach often utilizes sensors, gateways, and cloud platforms for integration.

Advantages of an IoT overlay:

• Lower initial investment: No need for complete replacement of expensive equipment.
• Faster implementation: Allows quicker realization of benefits from data collection and analytics.
• Minimized risks: Lower risk of downtime and operational disruption compared to a full replacement.
• Extended functionality: Adds monitoring, analytics, and predictive maintenance capabilities.

Disadvantages and risks of an IoT overlay:

• Limited control: An overlay can collect data but may not always provide full control over legacy systems.
• Integration complexity: Compatibility issues with proprietary protocols may arise.
• Security gaps: Legacy OT systems often have limited security features, creating vulnerabilities when connected to IoT networks. Even with network segmentation, without implementing gateways that filter commands at the application data level, an attacker within the segment can freely manipulate physical controllers, bypassing any firewalls.
• Scalability: Legacy systems may not withstand increased data loads.

Application scenarios for an IoT overlay include energy consumption monitoring, equipment health tracking, and data collection for analytics without direct intervention in core control processes. For example, using interface sensors like pulse meters allows legacy water or electricity meters to transmit data without significant modernization.

Full replacement of OT systems: Advantages, disadvantages, and application scenarios

A complete replacement of legacy OT systems with modern IoT-oriented solutions involves a full infrastructure overhaul, enabling maximum efficiency and flexibility.

Advantages of a full replacement:

• Scalability and flexibility: Modern architectures, such as microservices, allow easy integration of new components and technologies, ensuring long-term scalability.
• Improved security: New systems are designed with built-in security features, including encryption, authentication, and regular updates.
• Extended functionality: Enables advanced capabilities such as AI, machine learning, and edge computing for real-time analytics.
• Reduced operational costs: Modernized systems require up to 75% less maintenance effort.
• Long-term ROI: Provides significant return on investment through enhanced energy efficiency, automation, and security.

Disadvantages and risks of a full replacement:

• High initial investment: Significant costs for hardware, software, and implementation.
• Long implementation times: Projects can be lengthy, leading to extended downtimes.
• Migration complexity: Data transfer and integration with other enterprise systems can be challenging.
• Need for skilled personnel: Requires staff training to operate new technologies.

Application scenarios for a full replacement include building new smart buildings (BMS), modernizing industrial control systems (SCADA), and implementing comprehensive manufacturing execution systems (MES) that fully leverage the potential of IoT.

Key factors for making an architectural decision

The choice between an IoT overlay and a complete replacement of OT systems is a strategic decision that must be based on a comprehensive analysis:

• Budget and timeline: An IoT overlay is generally less costly and faster to implement, whereas a full replacement requires significant investment and time.
• Cybersecurity: As OT systems become more connected to the internet, the risks of cyberattacks increase significantly. OT security prioritizes continuous system operation and physical safety, while IT security focuses on data confidentiality and integrity. Modern IoT-oriented systems offer built-in security features but require careful planning and implementation of multi-layered protection strategies.
• Regulatory requirements and compliance: Some industries have strict regulatory requirements that may influence architectural choices.
• Internal team skills and resources: Assessing the team's capability to support and develop the chosen architecture is critical.
• Company strategic plans: Long-term scalability, flexibility, and the ability to integrate with future technologies are vital for competitiveness.

Organizations that effectively manage this process standardize data definitions and interpretations, organize data environments to ensure discoverability of relevant information, highlight signals requiring human attention, and provide secure access as the number of users and integrations grows.

Comparative table: IoT overlay vs. full OT system replacement

AZIOT provides expert support and solutions for infrastructure integration and modernization, helping companies develop and implement IoT overlay or full OT system replacement strategies, ensuring high levels of security and scalability. For more information on Intecracy Group solutions, visit Intecracy solutions and inbase.com.ua solutions.

The optimal architectural choice is not a universal solution but depends on the unique needs, constraints, and strategic goals of each organization. A thorough analysis of the current state, potential risks, and expected return on investment will enable an informed decision that ensures the long-term success of digital transformation.