An Overview of Industrial Communication Protocols

Industrial communication protocols are standardized sets of rules that govern the exchange of data among machines, sensors, programmable logic controllers (PLCs), and other industrial equipment. These protocols ensure that interconnected devices communicate effectively and consistently in industrial networks.
Some of the key messaging patterns used in industrial communication include:

• Request-response pattern: One machine requests data or commands and the other machine responds, as it is widely deployed in point-to-point communication
• Publish-subscribe pattern: Devices or systems publish data to each other or to an intermediate broker, and subscribers who have expressed interest in specific data sets begin to receive data as it's published

Let’s break down the most widely used protocols in industrial automation.

• Overview: MTConnect is an open, royalty-free protocol that standardizes the communication vocabulary for machine tools and manufacturing devices, ensuring interoperability
• Key uses: Found in manufacturing environments needing real-time production monitoring and analytics
• Strength: Provides consistent terminology between machines and software for manufacturing operations

Connect MTConnect-compliant applications and integrate data seamlessly with IT and OT applications.

• Overview: OPC UA is a highly versatile secure, cross-platform communications specification for industrial automation and IoT
• Key uses: Industrial automation systems and IoT-enabled devices requiring secure data exchange between diverse equipment, manufacturing systems, and IT systems
• Strength: Interoperable across operating systems such as Windows, Linux, and custom embedded architectures

Aggregate OPC servers and instances of Kepware into a single instance with OPC Connectivity Suite.

• Overview: This protocol employs standard Ethernet technology, integrating with the Common Industrial Protocol (CIP)
• Key uses: Facilitates high-speed, real-time communication for motion control, I/O, and device-to-device and device-to-host communication
• Strength: Its foundation on Ethernet and deep feature set offers robust scalability and flexibility for a variety of uses across automation settings, including machine-to-machine and integrations into IT systems

• Overview: A proprietary protocol developed by FANUC for computer numerical control (CNC) data exchange
• Key uses: Widely used in CNC operations to monitor or control FANUC devices with third-party systems
• Strength: Recommended for factories with FANUC machinery for enhanced productivity insights

• Overview: Originally developed in 1979 for communication with PLCs, Modbus remains a simple, performant, and widely supported protocol
• Key uses:
  • Modbus RTU: Communication over serial connections like RS-485
  • Modbus RTU over Ethernet: Serial-style Modbus RTU packaged in TCP/IP or UDP/IP
  • Modbus TCP/IP: Native Modbus communications over Ethernet networks
• Strength: Open and vendor-neutral, ensuring wide compatibility

Connect to the broadest variety of Modbus-enabled devices with the Modbus Suite.

• Overview: BACnet is widely adopted for building management systems (BMS), facilitating control over HVAC, lighting, fire detection, and access control systems
• Key Uses: Especially prevalent in automation for smart buildings
• Strength: Open standard supporting cross-vendor integration

Connect to building automation devices with the BACnet/IP driver from Kepware.

• Overview: Used for communication with CNC machines, particularly favored in Europe for precise control functions
• Key uses: Industrial machining environments with CNC systems requiring sophisticated data handling
• Strength: Offers high command granularity for specialized CNC applications

• Overview: A staple in both industrial and nonindustrial networks, enabling data exchange over Ethernet
• Key uses: Ubiquitous data transfer protocol; typically leveraged any Ethernet-based communications network from legacy industrial systems to modern IIoT ecosystems
• Strength: Universally adopted with robust compatibility across software and hardware, usually as part of basic Ethernet feature set

• Overview: A point-to-point protocol that integrates sensors and actuators with automation systems, enhancing diagnostics and simplifying configurations
• Key uses: Frequently employed to retrieve sensor diagnostics or adjust settings, improving predictive maintenance tasks
• Strength: Supports rapid device parameterization, while delivering detailed diagnostics

• Overview: UMATI is a global initiative for open communication interfaces, where machine-building industries and their customers can leverage OPC UA as its foundation in a standards-based approach, allowing for broad compatibility across different manufacturers and platforms
• Key uses: Standardizes integration with machinery as part of manufacturing, IT, and Industry 4.0 ecosystems
• Strength: Promotes modularity and vendor agnosticism in machine tool communication

Modbus is recognized as the most widely implemented protocol, owing to its time in the market, wide vendor support, simplicity, performance, and openness. With options like Modbus RTU for legacy systems and Modbus TCP/IP for modern networks, it supports seamless integration with diverse industrial systems.

Here’s a compiled list of protocols catering to specific applications:

• Widely used protocols: Modbus, Ethernet/IP, PROFINET, PROFIBUS, OPC UA, BACnet
• Emerging protocols: Message Queuing Telemetry Transport (MQTT) and UMATI
• Legacy systems protocols: RS-232, RS-485, CAN bus

Key Takeaways and Next Steps
Industrial communication protocols form the backbone of enterprise connectivity in increasingly digitalized ecosystems. Leveraging these systems ensures operational efficiency and makes predictive maintenance, real-time tracking, and enhanced interoperability achievable.

To explore how industrial communication protocols can be tailored to your operations, visit Kepware and learn about solutions providing reliable, standardized, and secure industrial connectivity.