RTU is the abbreviation of REMOTE TERMINAL UNIT, which is a remote data terminal, used for monitoring, control and data collection applications. It has telemetry, remote signaling, remote adjustment and remote control functions. The RTU function must ensure two functions: 1. Data transmission function; 2. Collection and control function.
After many years of PLC DTU, this method has been commonly used in industrial automation applications for online monitoring and remote control of data. When RTU came out, the integrated A/D and I/O acquisition functions of RTU were able to replace some PLC functions.
Advantages of RTU:
1. In some relatively simple data collection and monitoring of temperature, pressure, humidity, water level, smoke and other sensors, RTU can completely replace the early PLC DTU method at the front end, which can not only save project construction costs, but also simplify the front-end equipment connection and The complexity of interface compatibility issues.
2. In some front-end equipment status monitoring and switch control, alarm and control are also realized through the I/O of the RTU. For example, the switch status of the equipment can be controlled based on the drive level of the front-end equipment, or the change in the voltage value of the front-end dry contact can be detected to determine the front-end equipment. working condition.
3. Supports three types of standard Modbus protocols: Modbus RTU , Modbus ACSSI, and Modbus TCP/IP protocols, and can be seamlessly connected to most front-end equipment manufacturers and back-end mainstream configuration software in current industrial automation.
4. ZHC1921 is a RTU series product independently developed and produced by Chengdu Zongheng Intelligent Control. It supports 4-way Socket, local logic processing operations, automatic collection and active reporting, DO remote follow AI/DI, configuration cloud real-time monitoring PLC and other functions, and has excellent expansion performance. .
Modbus was invented in 1979 by Modicon (now a brand of Schneider Electric) and is the world’s first bus protocol truly used in industrial fields.
ModBus network is an industrial communication system, which consists of a programmable controller with an intelligent terminal and a computer connected through public lines or local dedicated lines. Its system structure includes both hardware and software, and it can be applied to various data collection and process monitoring.
Modbus has the following characteristics:
1. Standard and open. Users can use the Modbus protocol for free and with confidence. There is no need to pay license fees and it will not infringe on intellectual property rights. Currently, there are more than 400 manufacturers supporting Modbus and more than 600 products supporting Modbus.
2. Modbus can support a variety of electrical interfaces, such as RS232, RS485, etc., and can also be transmitted on various media, such as twisted pair, optical fiber, wireless, etc.
3. The frame format of Modbus is simple, compact and easy to understand. It is easy for users to use and easy for manufacturers to develop.