What are communication and network?
So-called Communication (COMMUNICATION)
→ A method of communicating and exchanging information using electrical equipment
So-called Network (NETWORK)
→ The route taken during the communication process
Two main components of a network
1 Hardware → Communication interface / Communication line
2 Software (Firmware) → Communication protocol (protocal)
What is an Industrial Communication Network?
- Industrial communication networks refer to the related components and technologies used for communication in automation control and process control within industrial environments. Industrial control networks and general communication networks are the same in terms of the transmission signals used, but there are very large differences in the characteristics of the products themselves. Industrial control network equipment needs to adapt to complex and harsh industrial field environments, such as temperature, humidity, or electromagnetic interference, and also includes installation scale, data accuracy, stability, security, and construction costs.
Industrial Communication Network Applications
- For example, in a large work site where many different pieces of equipment (such as dryers or oil tanks) are scattered, the most efficient way to monitor the status (pressure, temperature, oil level) of these devices is to use network communication modules to connect them. At this time, each piece of equipment is regarded as a node, and the status of each device is detected and recorded one by one. Once the pressure is higher or lower than the set point, the module can immediately transmit this information to the Facility Management Control System (FMCS), achieving real-time status updates while completing the monitoring task safely and cost-effectively.
Advantages and Disadvantages of Various Industrial Communication Networks
- Currently, no single industrial communication technology can meet all application needs. In the evolution of industrial networks, many proprietary technologies developed solely for specific target applications have led to market confusion, making it difficult to determine which technology is the best industrial network solution. To organize the market, various standardization organizations have united to jointly formulate network interfaces and technical standards specifically for industrial use, generally referred to as Field Bus. The greatest benefit of this standardization is the provision of interoperability between equipment from different suppliers, involving only minimal installation changes. In addition, these organizations have established many standards specifically for different applications, and common industrial communication standards include Modbus, Ethernet IP, ProfiBus, DeviceNet, etc.
- Although it is currently difficult to definitively say which industrial communication standard is most suitable for industrial networks, setting this issue aside, what is more important is that the relevant settings may only be applicable to a certain type of installation, and each installation will have its own suitable topology (hardware distribution configuration). In other words, the same equipment may require a star configuration in one situation but a redundant ring in another, and this decision depends on many factors, including communication protocol characteristics, installation scale, environment, equipment, safety, and cost.
Types of Industrial Communication Networks
MudBus
- Modbus is a serial communication protocol developed by Modicon in 1979 for its own PLCs (Programmable Logic Controllers). It features standardization, free usage, and an open architecture, and is widely used in the industrial automation industry. Through Modbus, various other devices can be easily integrated.
- The Modbus protocol currently exists in versions for Modbus RTU, Modbus ASCII, and Modbus TCP/IP.
The Modbus protocol is a master/slave protocol. One-to-many (one master station to multiple slave stations), where each slave device has a unique address. Up to 247 addresses (devices) can be connected on a single data link, with a maximum communication distance of 1200M. Only the node designated as the master station can initiate a command (on Ethernet, any device can send a Modbus command, but usually only one master node device initiates instructions). - A Modbus command contains the Modbus address of the device intended to execute it.
All devices receive the command, but only the device at the specified address will execute and respond to the instruction. MODBUS TCP/IP is Ethernet providing the Modbus serial communication protocol. The difference between the two is that the serial protocol requires the calculation of a checksum and its use as a way to confirm data, while the Ethernet version does not.
P.S. Our company's dryers use the Modbus RTU communication protocol as the standard communication configuration.
ProfiBus
- PROFIBUS is a fieldbus standard used in automation technology, promoted in 1987 by fourteen companies including Siemens and five research institutions in Germany. ProfiBus is an abbreviation for PROcess FIeld BUS.
- ProfiBus is a multi-master system that allows multiple control, configuration, or visualization systems to operate with each other on one bus. A master station with access rights can send data without an external request. A slave station, on the other hand, is a passive device that does not have bus access rights. A slave station can only acknowledge received messages or transmit when requested by the master. Up to 126 addresses (devices) can be connected on a single data link.
- The physical layer is an improved version of the RS-485 standard, which adds several requirements to enhance data transmission performance.
DeviceNet
- DeviceNet is a standard serial communication protocol developed by Allen-Bradley in the United States in 1994.
- DeviceNet is a standard serial communication built on the CAN Bus. Due to its superior characteristics such as safety, speed, and noise resistance, it is widely used in industrial communication networks. It supports distributed real-time control, effectively collecting the status of remote devices such as sensors or solenoid valves, providing the control end with integrated and real-time data. In addition, its wiring-saving feature can effectively reduce wiring costs and time, relatively simplifying the complexity of wiring and reducing the occurrence of errors. DeviceNet also has a unique arbitration mechanism, which ensures that remote devices do not receive error data when two or more nodes transmit messages simultaneously, protecting data security, and one packet is correctly delivered to the destination without both sides simultaneously backing off to wait. Each DeviceNet network can connect up to 64 devices.
EtherNet IP
- EtherNet / IP is an industrial Ethernet communication protocol developed by Rockwell Automation, and can be applied in process control and other automation applications. It is part of the Common Industrial Protocol (CIP).
- Each network node has its own unique Ethernet. Therefore, all network devices have a unique (non-repeating) network address. IP Address (Internet Protocol Address) is used as a unique address to identify hosts on the network, just like people's addresses. Data on the network can only successfully find its destination through IP.
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