- ModBus is a protocol that can be understood as a language.
- For example, if Xiaocheng speaks Chinese and Xiaoli speaks English, and they meet on the way, Xiaocheng will talk a lot and Xiaoli won't understand anything. So if Xiaocheng and Xiaoli want to communicate, they need to figure out what each other is saying. First, they need to use the same language. Why use an RTU serial port server
- Now both Xiaocheng and Xiaoli have learned Chinese and are ready to communicate. They can speak face-to-face and chat on WeChat by typing;
- Talking and communicating can be understood as RTU communication (shielded twisted pair cable); Typing chat can be understood as TCP communication (Ethernet cable). The language of communication between them has not changed, it is still Chinese, only the way of communication has changed.
- The communication methods have changed, with one being communication and the other being writing. This is reflected in the ModBus protocol, where one is ModBus_STU and the other is ModBus_TCP, and the two types of wiring are also different.RTUIt is serial port wiring, such as RS-485, RS-232, RS-422, which is connected by shielded twisted pair cables and hand pulled;TCPIt's an RJ45 Ethernet interface, which is a crystal head Ethernet cable.
- （2） For example, Xiaocheng and four children are going to talk in Chinese.
- 1. Xiao Cheng is talking to A, and only when Xiao Cheng asks A can A answer Xiao Cheng. If Xiaoming doesn't ask, A won't answer. This mode is called "half duplex", where you can only answer when asked, and not answer when not asked. What is half duplex mode
- 2. Xiaocheng is preparing to ask each of the four children A, B, C, and D some questions. Xiaoming is the main station, and ABCD are the secondary stations. ABCD4 children are numbered one by one, A is 1, B is 2, C is 3, D is 4, and these 1, 2, 3, and 4 are the addresses of the slave stations. What is a master station, what is a slave station, and what is a Modbus address
- 3. Xiaocheng asked A, and A began to answer. After A finished speaking, Xiaocheng began to ask B. The interval between A and B is called the "polling interval". If A hasn't finished speaking yet and Xiaocheng starts asking B, then A won't be able to finish listening and the data won't be complete. What is polling interval
- 4. Xiao Cheng asked A, and they both speak very fast, which is the baud rate. If they speak too fast, Xiao Ming needs to get closer to A, otherwise he won't be able to hear clearly; Speak slowly, and you can stay further away. A baud rate of 9600 results in slower transmission speed compared to 19200, but with longer transmission distance. (What is baud rate? Why is the lower the baud rate, the farther the transmission distance?)
What are the communication protocol characteristics of Modbus? Can I explain in the simplest language?
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modbus Technical Team
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