Programmable logic controllers (PLCs) are an integral part of factory automation and industrial process control. PLCs control a variety of analog and digital sensors and actuators, and communicate over simple to complex interfaces in varying protocols. In addition to control functions, PLCs perform signal processing and data conversion. But in the future, PLCs, driven by developments in the Industrial Internet of Things (IIoT), will deliver scalable solutions that are secure, high performance, low power, small footprint, and are ready for Industry 4.0 with built-in secure communications to enterprise IT systems.
Backgrounder on PLCs
Since their introduction a few decades ago, PLCs have evolved from simple input-output controllers to complete processor-based systems that execute complex control algorithms. But PLCs have undergone significant form-factor changes over the years from industrial PCs and Programmable Automation Controllers (PAC) in PC-like form-factors to compact enclosures and mini-PLCs. The scope of PLC functionality has also evolved. In addition to discrete control functions, PLCs have integrated functionality such as Human Machine Interface (HMI), motion-control, real-time industrial Ethernet, and data communication gateways.
The demand for additional features, precision, and connectivity on the factory floor has driven the increasing integration of PLCs and its associated technologies. It has been sustained by PLC component cost reductions and the availability of higher performance processing engines. In general, the evolution of PLC functionality has followed the industrial automation demand curves of features, performance, and lower power. Following that trajectory, the demands of Industry 4.0 and IoT, to a large measure, will drive future PLC architectures.
Challenges of PLC Design Today
The current manufacturing automation environment of Industry 4.0 demands high performance PLCs enabled with secure enterprise connectivity and HMI. Today, multiple international Industry 4.0 initiatives rely on cyber-physical systems to implement the promise of smart manufacturing, leveraging connected systems for Machine-to-Machine (M2M) and enterprise interaction. Making PLCs ready for Industry 4.0 is fraught with new challenges, requiring grounds-up PLC redesign. The major challenges confronting PLC designers today include:
- High-performance control: Smart-manufacturing environments require PLCs to process instructions, service interrupts, and support integrated HMI at speeds faster than ever before. This need has led to the use of more powerful processors with higher MIPS and multiple cores, resulting in high cost and power consumption penalties.
- Connectivity: Deterministic M2M connectivity between disparate machines requires support for multiple Industrial Ethernet protocols (including newly emerging standards-based deterministic Ethernet such as IEEE 802.1 TSN) within a single PLC system. Enterprise connectivity demands application interoperability frameworks such as OPC-UA.
- Secure communications: PLCs connected outside the factory network and to the enterprise are vulnerable to cyber-attacks, making security a significant concern.
- Cross-platform interoperability: Choosing the wrong processor or ASSP can be an expensive error. Functional interoperability between diverse systems requires standardized operating systems running on non-proprietary processor cores.
- Future proofing: With an ever-evolving connectivity and interoperability environment, changes in market requirements are more frequent, leading to software and hardware changes.
PLC Design with SoC FPGAs for Industry 4.0
System-on-Chip (SoC) FPGAs, which combine a processor and FPGA fabric on a single chip, present a unique alternative for overcoming today’s PLC design challenges. Manufacturers who use SoCs in PLC architectures can derive the following benefits:
- High performance
- 4,600 DMIPs for less than 1.8 W
- Up to 1,600 GMACs and 300 GFLOPS based on >125 Gbps processor to FPGA inter-connect and cache coherent hardware accelerators
- Lower power—Up to 30% less power vs. a two-chip discrete solution
- Reduced BOM and PCB space and layer cost—Up to a 55% form factor reduction
- Scalability and investment protection—Scalable SoC processor roadmap grows with application needs and protects software development investment
- Flexibility—SoC FPGAs can accommodate software and hardware changes
- Improved time to market
To learn more about PLC design using SoC FPGAs, please download the attached document by Altera, called "," which was the source of information for this document.
 | Altera - PLC Architecture in the Industry 4.0 World.pdf |