For more than three decades, IEC 61131-3 has been the foundation of PLC programming in industrial automation. It standardized programming languages such as Ladder Diagram (LD), Structured Text (ST), and Function Block Diagram (FBD), enabling engineers worldwide to build reliable control systems.
However, modern industrial environments have changed dramatically.
Today’s smart factories require:
Distributed intelligence
Edge computing
Real-time data processing
Cloud integration
AI-assisted automation
Flexible scalability across multiple devices
As production systems become larger and more interconnected, the limitations of traditional centralized PLC architectures are becoming increasingly apparent.
Traditional PLC systems are typically centralized, where one main controller manages the entire production line.
This architecture introduces significant risks:
If the PLC fails, the entire line may stop
Maintenance becomes increasingly difficult as programs grow
Modifying one logic section can impact the entire system
As industrial systems scale, PLC projects often become oversized and difficult to maintain.
Most traditional PLC platforms rely heavily on proprietary ecosystems.
Changing PLC vendors often requires:
Learning new programming software
Rebuilding communication structures
Adapting to different instruction sets
Reconfiguring industrial protocols
This creates long-term dependency on a single vendor and limits system flexibility.
Conventional PLCs mainly rely on cyclic scan execution models designed decades ago.
While effective for traditional automation tasks, this architecture struggles with:
Event-driven applications
Cloud-native communication
Distributed edge processing
AI model integration
Real-time data orchestration
Modern industrial systems increasingly demand decentralized processing closer to sensors and actuators.
IEC 61499 introduces a modern distributed automation architecture based on event-driven function blocks.
Instead of placing all logic inside one centralized PLC, control logic can be distributed across multiple intelligent devices.
Unlike cyclic scanning PLCs, IEC 61499 executes logic only when events occur.
Benefits include:
Faster response times
Lower CPU usage
Improved system efficiency
Better scalability
This model is especially suitable for edge computing and distributed IIoT systems.
IEC 61499 allows function blocks to run on multiple devices simultaneously.
For example:
One function block can run near sensors on an ARMxy industrial controller
Another can run near actuators on an EdgePLC
Devices communicate through MQTT, OPC UA, or industrial Ethernet
This distributed architecture significantly improves reliability and flexibility.
IEC 61499 introduces software engineering practices rarely seen in traditional PLC systems:
Modular programming
Reusable components
Portable logic
Network-based orchestration
Device-independent deployment
This approach resembles modern distributed software systems rather than conventional hardwired automation logic.
Traditional PLC:
Modify the main PLC project
Stop production
Download updated firmware
IEC 61499:
Add a new distributed node
Deploy function blocks online
Minimal production interruption
Traditional PLC:
Proprietary protocols
Multiple protocol gateways
IEC 61499:
Native MQTT and OPC UA support
Event-driven communication between nodes
Traditional PLC:
One controller failure may affect the entire line
IEC 61499:
Other distributed nodes continue operating
Fault impact remains localized
Traditional PLC:
Migration between vendors is extremely difficult
IEC 61499:
Function blocks can be exported and reused
Compatible with multiple runtimes through 4diac IDE
At BLIIOT, we run FORTE Runtime directly on ARMxy industrial controllers and EdgePLC platforms.
Engineers can:
Develop logic using 4diac IDE
Deploy distributed function blocks over the network
Scale systems across multiple edge devices
Integrate cloud and edge applications seamlessly
Compared with traditional PLC architectures, distributed automation systems offer:
Higher scalability
Better fault tolerance
Lower maintenance costs
Easier future expansion
In many industrial projects, the budget of a single high-end PLC can be replaced by multiple distributed edge controllers with significantly improved flexibility.
Industrial automation is moving from:
Centralized control
to
Distributed collaborative intelligence
IEC 61499 is no longer just a research concept. It is becoming a practical architecture for next-generation smart factories, industrial IoT systems, and edge-native automation platforms.
As edge computing, AI, and cloud integration continue to reshape manufacturing, distributed automation will become an essential part of Industry 4.0 infrastructure.
