Communication Protocols

Communication protocols are rules and procedures that ensure data is correctly exchanged between different devices and systems. By using these protocols, devices from different manufacturers and with different functionalities, such as computers and printers or smartphones and headphones, can communicate effectively. Just as humans need a common language to converse smoothly, machines also require a “common language” in the form of communication protocols.

The diagram illustrates that computers need a common protocol to communicate with each other. Without a common protocol, information cannot be transmitted correctly and communication fails. Communication protocols define how data is sent and received, error handling, and the timing of data transmission, ensuring proper communication by adhering to these rules.

For example, well-known protocols include TCP/IP for internet connections, HTTP for browsing websites, and POP and SMTP for email transmission. In addition to these, various protocols are used for communication between devices, and here are some examples:

• ① Highway Addressable Remote Transducer (HART®)

HART is a communication protocol used in industrial equipment, particularly in process control. It was developed to complement communication between devices that originally used analog signals, hence it is called a “hybrid communication protocol.” It features the ability to send and receive data using both digital and analog signals, transmitting digital signals over analog ones to provide the convenience of digital communication even with existing analog devices. HART is commonly used between sensor devices like pressure gauges, thermometers, flow meters, and control devices like PLCs (Programmable Logic Controllers). Using this protocol enables the monitoring of data and status from devices and the collection of maintenance information.



• ② Building Automation and Control Networks (BACnet)

BACnet is a communication protocol primarily used in building control systems for HVAC, lighting, and security. As an open standard, one of its key features is allowing data exchange between devices from different manufacturers. BACnet operates over communication media like Ethernet and RS-485, using protocols such as IP, making it flexible for various environments. This enhances overall system operational efficiency and reduces long-term maintenance costs.



• ③ Open Platform Communications Unified Architecture (OPC UA)

OPC UA is a highly powerful and flexible communication protocol used in the field of industrial automation. It evolved from OLE for Process Control (OPC), the standard for industrial automation, and features the flexibility to handle data security and remote communication over the internet, and a platform-independent structure. OPC UA provides a standard communication foundation for data exchange between different systems and devices, offering diverse functionalities to integrate with a wide range of industrial systems.

Communication protocols support smooth information exchange between different devices and systems. They are widely used in various fields such as industry and IoT, and will contribute to future technological innovation.

*HART® is a registered trademark of the FieldComm Group.
*BACnet is a trademark of ASHRAE.
*Ethernet is a trademark of FUJIFILM Business Innovation Corp. in Japan and/or other countries.
*OPC and OPC UA are trademarks of the OPC Foundation.