What Is the Difference Between Ethernet and Serial Communication?

With the further development of Ethernet and its application in the field of industrial control, more and more products will provide Ethernet interfaces. However, devices that only provide serial communication will still exist for a certain period of time. Therefore, it is a good choice to use an RS485 Ethernet converter to integrate serial devices through Ethernet.

The RS485 Ethernet converter solves the conversion from the RS232/485/422 serial port to the network port. How does the user software communicate with the converter? RS485 Ethernet converter provides four software solutions: virtual serial port, Socket programming, DLL library, and Modbus TCP.

Virtual serial port: after the user uses the TCP/IP RS485 Ethernet converter. There is no need to modify the original software (the serial port device should have software running on the computer to communicate with the device). The RS485 Ethernet converter software program of PUSR can be used to simulate virtual serial ports such as COM4 and COM5. Then COM4 and COM5 are bound with the specified RS485 Ethernet converter through software. After that, the user software opens COM4 and COM5, which is the same as opening COM1 and other hardware serial ports. The use of a virtual serial port can be considered for users who already have serial port software, but for users who have not yet designed software. It is recommended to use Socket programming, because Socket programming is more efficient than virtual serial port, and there is no need to install drivers.

Socket programming is to develop network programs by using the development environment of Windows/Linux and other operating systems. Communicate directly with the TCP/IP converter. The protocol is transparent transmission, that is, the serial port receives what the network sends, and vice versa. Users can choose Socket programming provided by VC, VB, Delphi, C #, and other development environments. For example, connecting to an RS485 Ethernet converter in server mode is a call to the Connect function. The parameters are the IP and port of the RS485 Ethernet converter.

Use DLL library: DLL is a dynamic link library that uses Socket programming encapsulation for the basic operation of the RS485 Ethernet converter. The user can use the DLL library to realize the search, parameter setting, and communication functions of the RS485 Ethernet converter. Compared with Socket programming, the DLL library is more powerful and more convenient to call. However, for users who are familiar with network programming, users still want to use Socket programming to design programs. I don't want to bring a lot of DLLs with my software.

Modbus TCP: The user software uses the standard Modbus TCP protocol. The serial port to TCP/IP can directly convert the Modbus TCP data stream of the network port into the Modbus RTU data stream. The serial port of the RS485 Ethernet converter can communicate with the user's serial device in Modbus RTU mode. The RS485 Ethernet converter can be used as a Modbus gateway to enable standard Modbus TCP software to access standard Modubus RTU devices.

The RS485 Ethernet converter is used to convert TCP network data packets or UDP data. It is a device that realizes transparent data transmission with 1 RS232 and 1 RS485 interfaces. Low power consumption, high speed with ARM processor. The TCP/IP protocol stack integrated into the module can easily complete the network function of the embedded device. Integrated 10/100M adaptive Ethernet interface. The highest baud rate of serial communication is 1024Kbps. Products with TCP Server, TCP Client, UDP, Httpd Client, and other working modes have passed rigorous tests. In banks, highways, large corporate networks, busy networks with cameras, and complex network rings formed by fiber to Ethernet, etc. All of them have been successfully applied.

What is the difference between Ethernet and serial communication?

1. Configuration of Ethernet equipment is more flexible and convenient

The communication between multiple RS232 serial devices and the computer is generally through the multi-serial port card on the PCI slot of the computer or through the USB serial port connected to the USB. To realize the expansion of the RS232 serial port by serial hub, the number of PCI slots or USB interfaces of each computer is limited. So that the number of RS232 serial devices communicating with the computer is limited accordingly. Although the RS485 bus has simple wiring and many load devices, the communication distance can reach 1200 meters. But must be routed in a daisy-chain hand-in-hand topology, Adding equipment on the RS485 bus needs to lay the line in the past or solve the wiring problem by adding 485 repeaters or 485 hubs. But Ethernet is different, as long as there is a network information port. You can directly connect the relevant Ethernet devices to the Ethernet, and the number of access devices is basically unlimited.

2. Support hot plug work

The related equipment can be configured when the system is working without stopping the system. For example, when the computer needs to add a multi-serial port card to expand the number of RS232 serial ports. You need to shut down the computer and open the case to add a multi-serial port card. When a corresponding 485 device is added to the RS485 bus, the line needs to be interrupted before the corresponding device can be added. Adding corresponding Ethernet equipment the Ethernet only needs to connect a network cable to a nearby information port. It can work normally by configuring the relevant software on the computer.

3. Simple and easy to use, convenient and simple maintenance in the later period

No Matt RS232 equipment or RS485 bus communication is generally communicated with a single computer. It is difficult to form a dual-server redundant hot backup system. It is very easy to configure a dual-server redundant hot backup system on Ethernet. In the same way, RS232 serial communication or RS485 bus communication can not form redundant links. Once there is a problem, the whole system may collapse, especially the RS485 bus, on which there is a problem (such as a short circuit). It is easy to cause the whole system can not be used, and it is very difficult to find the fault point on the RS485 bus, which needs to be checked one by one. But that communication method based on industrial Ethernet can avoid similar problems. Industrial Ethernet switches are used to lay ring redundant links in industrial networks. Once a link goes wrong, It can self-heal and recover within 20ms and prompt maintenance in time.

4. High scalability and high scalability, very suitable for flexible wiring

Ethernet equipment is flexible and convenient to work by hot plug and configuration. Using Ethernet as a means of communication, there is no limitation on distance and quantity, and the communication distance of the RS485 bus is 1200 meters. The communication distance can be extended by adding a 485 repeater or converting the signal into an optical signal through an optical fiber modem and transmitting the signal through an optical fiber. However, there is always a limit to the distance of transmission, and Ethernet can be used to connect to the Internet. Through the Internet, data can be exchanged anywhere in the world where there is a network connection. The maximum rate of RS485 bus long-distance communication is 110Kbps, and now Fast Ethernet (100m) has been basically popularized. Gigabit Ethernet is gradually entering the field of industrial control. There is basically no limit to the communication capacity of Ethernet and the number of devices communicating on Ethernet.

The real "integration of management and control" is realized through Ethernet communication. With the development of automation of industrial control and office systems. Now the goal of "integration of management and control" in the field of industrial control has been put forward. That is to say, the industrial control system and the office automation system can be closely integrated, and the information exchange can achieve seamless docking. Because the current office system is based on Ethernet for data exchange, all software is based on Ethernet. Communication with an Ethernet device can be done directly without any modification, It can quickly integrate the relevant data of Ethernet equipment in the industrial control network into the office automation system.