In a broad sense, communication refers to the mutual connection between all things. Communication between people, such as phone calls, WeChat messages, and face-to-face conversations, is one form of communication. The propagation of ultrasound is also a form of communication. Everything we see, hear, and feel can be considered a form of communication. Therefore, communication is everywhere. But what is the purpose and role of this omnipresent communication?

The purpose of communication in life is to exchange information and acquire knowledge, thereby increasing one’s experience and understanding. Communication between industrial devices serves the same purpose: to acquire device parameter information or to control other devices. Many modern devices are not isolated; most of them need to communicate with other devices. So, what communication methods are available?

Based on the direction of data transmission:

• Simplex Communication: Data can only be transmitted in one direction. (Similar to a one-way single-lane road)

• Half-Duplex Communication: Data can be transmitted in both directions, but only one direction at a time. (Similar to a controlled two-way single-lane road)

• Full-Duplex Communication: Data can be transmitted simultaneously in both directions. (A truly bidirectional single-lane road)

RS232 Interface

A three-wire (RX, TX, GND) full-duplex serial communication interface that only supports one-to-one communication, with a theoretical communication distance of 15 meters.

RS422 Interface

A four-wire (RX+, RX-, TX+, TX-) full-duplex communication interface. It supports one-to-many communication, with a theoretical maximum communication distance of 1200 meters.

RS485 Interface

A two-wire (A, B) half-duplex communication interface. It supports one-to-many communication, with a theoretical maximum communication distance of 1200 meters.

CAN Interface

A two-wire (CANH, CANL) half-duplex communication interface that supports one-to-many and many-to-many communication, with a theoretical communication distance of up to 1000 meters. It is widely used in automotive electronics.

RJ45 Interface

The RJ45 interface, also known as the Ethernet interface (crystal head), is an eight-wire full-duplex interface. In Ethernet's eight-wire interface, only four wires (RX+, TX+, RX-, TX-) are actually used.

The theoretical communication distance is 100 meters, but it can be extended through various gateway devices.

These communication interfaces are the most commonly used in industrial settings. Having a communication interface only establishes a physical communication path, similar to the various roads in our daily life. To ensure the safe and orderly operation of these roads, traffic rules need to be established. Industrial communication is the same—it requires rules and protocols to ensure orderly operation.

In communication links, to ensure multiple parties effectively and reliably receive the correct data, a set of rules must be established. This collection of rules is the communication protocol. Every protocol is developed to solve a specific issue, and the continuous application and improvement of these protocols eventually becomes international standards. Communication protocols that become international standards can be applied globally, leading to the development of products that support these protocols.