The transition from isolated SCADA systems to unified data exchange standards is a key challenge when implementing the Industrial Internet of Things (IIoT) and Edge AI. Attempts to directly connect legacy equipment to the cloud create critical vulnerabilities in the operational technology (OT) environment and lead to a loss of data context. An effective solution is building a hybrid architecture where Modbus, MQTT, and OPC UA interact via intelligent edge gateways.
Protocol synergy: Modbus, MQTT, and OPC UA
In an industrial environment, there is no single universal protocol, so popular standards must complement each other:
- Modbus is a classic protocol for reading metrics from legacy equipment. It is simple but lacks built-in security features and metadata.
- MQTT is a lightweight transport protocol ideal for transmitting data over unstable communication channels, but it requires external structuring.
- OPC UA is an architecture that allows building complex information models with rich semantics, but it requires significant computing resources.
Bridging the semantic gap
Retrieving raw values from Modbus registers without context makes the data useless for analytics. Using OPC UA at the edge gateway level allows translating raw metrics into standardized objects with metadata before sending them to industrial analytics systems.
An optimal three-tier architecture includes:
- Field level: controllers reading parameters via local protocols (Modbus).
- Edge level (gateways): collection, primary filtering, normalization into OPC UA semantic models, and local event processing.
- Cloud level: transmission of aggregated telemetry via MQTT.
Specialized teams are engaged to implement such solutions. In particular, Softengi developers (a member of Intecracy Group) provide edge-level integration and custom IoT solution development. At the enterprise level, integration is powered by the UnityBase low-code platform, which ingests normalized IIoT data via automatically generated REST APIs with strict access control.
OT segment security according to ISA/IEC 62443 standards
The nature of legacy industrial equipment often makes modern patching methods impossible. To protect systems, the concept of segmentation (Zones and Conduits) from the ISA/IEC 62443 standard is used:
- Isolation in zones: legacy controllers are grouped into physically isolated segments with no external access.
- Controlled channels: communication between zones is carried out exclusively through edge gateways that filter traffic.
- Telemetry protection: the gateway collects unsecured data within the zone and transmits it to higher levels in encrypted form.
The effect on the market
Adopting a hybrid IIoT architecture allows industrial enterprises to modernize legacy infrastructure without costly equipment replacement. By bridging the gap between OT and IT securely, businesses can leverage cloud analytics and low-code integration platforms like UnityBase to optimize operations while maintaining strict compliance with cybersecurity standards.
Recommendations
To minimize the risks of deploying IIoT infrastructure, enterprises should follow these practical steps:
- Conduct a comprehensive asset audit of existing legacy equipment and protocols.
- Design secure network zones and conduits according to the ISA/IEC 62443 standard.
- Implement intelligent edge gateways to handle local data collection and traffic filtering.
- Perform semantic normalization of raw metrics into OPC UA models at the edge level.
- Set up secure data transport using MQTT to deliver normalized telemetry to corporate systems and cloud analytics.
Prepared by a Software Ukraine member. Original publication.