4G Modem is used for wireless network data transmission of industrial equipment. This paper mainly analyzes the 4G modem from three aspects: appearance interface, usage method and application environment.
The appearance interface of 4G Modem generally only provides serial port interface networking mode. 4G Modem is mainly used for bidirectional transparent transmission between serial data and IP data.
The main purpose of 4G Modem is to achieve dial-up, not a gateway in the true sense. For example, after 4G Modem is connected to the terminal device and the dialing process is completed, 4G Modem can be used as a new network device, and the terminal device address can use the 4G Modem to bind address.
The transmission distance of 4G Modem application in field terminal is relatively scattered, and the data communication rate is high. Therefore, 4G Modem real-time performance can satisfy most industrial fields, which is usually used for data acquisition and monitoring systems, such as applications in the charging pile remote monitoring system, the environmental detection system, real-time energy consumption monitoring, dam water conservancy project monitoring, etc.
4G Modem data access generally provides serial port or network interface, but it is used to dial-up, not a gateway in the true sense. For example, after 4G Modem is connected to the terminal device and the dialing process is completed, 4G Modem can be used as a new network device, and the terminal device address can use the 4G Modem to bind address; the 4G Modem with the network interface is similar to the telecom ADSL Internet access, and generally requires the device to complete a dialing action.
The IP address used by the terminal device using 4G Modem is generally the IP address assigned by the UIM card dialing (the IP address is specified by 3A), having the IP address assigned, it can communicate with the server system. After the data of the terminal device passes through 4G Modem, the content transmitted by the wireless network is generally only processed by the IP header, intercepting the data transmitted in the wireless network, the transmitted data can be displayed by simply removing the header information; at the same time, the data is not processed accordingly, the 4G Modem may cause the replay or retransmission of the wireless data, resulting in an abnormality of the system, so as to pose a security risk.
4G Modem data exchange uses the data exchange process within the wireless network provider, enabling wireless network providers to easily access any system at both ends of the communication.
The 4G Modem terminal device has a certain relationship with 4G Modem, it can easily access other terminal devices, if a terminal device is controlled by a virus or by an outsider, all terminal devices and central server systems will be seriously threatened.
When the terminal device is accessed by the server using the 4G Modem, a route to the terminal device is added to the server to use the access interface of the wireless network provider as a gateway (or as a related route).
4G Modem does not perform related filtering during data transmission, so other machines can directly send some illegal information to the device terminal through the network, at the same time, 4G Modem increases unnecessary network traffic; also the data is not processed accordingly, the 4G Modem may cause the replay or retransmission of the wireless data, resulting in an abnormality of the system, so as to pose a security risk.
4G Modem generally does not compress data during data transmission.
Transmission data process, 4G Modem does not have no other intermediate server, but directly connects to the central server.
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