The LTE modem is the terminal module used to realize wireless data transmission. It is usually connected with the lower computer to realize the purpose of wireless data transmission. It has the title of "mobile phone in the industrial field", because its transmission principle is basically the same as that of the mobile phone we usually use. Typical devices include wireless data transmission, wireless router, wireless modem and other devices.
Wireless data transmission modem (modem wireless modem) is a data transmission device that fully supports 4G/3G/2G communication networks of China Mobile, China Unicom and China Telecom, and realizes bidirectional, transparent and wireless transmission between serial devices and servers, and between serial devices. The wireless data modem has the characteristics of simple use, USB/Bluetooth parameter setting, remote maintenance, etc., and can easily develop user monitoring software or dock with a third-party application platform through cloud platform forwarding, protocol development kit, network to serial port tools, etc.
1. Three-layer system protection: On the basis of the original two-level system protection (software protection + CPU built-in watchdog protection, external hardware watchdog protection), a level of system monitoring protection SWP is added, which completely solves the difficult problems such as "false online", "false crash" and "crash" in the industry;
2, large cache: can provide 16m customer transmission data cache, to solve the data loss caused by network bottlenecks;
3. High-speed processing CPU: The industrial CPU with extremely high-speed ARM9 is adopted, which can process various protocol data conversion at a higher speed and avoid data retransmission and loss caused by slow CPU processing speed;
4. Automatic acquisition of DNS: The DNS is automatically acquired, and it is no longer necessary to manually configure and input the DNS, thus avoiding the serious phenomenon that the modem device crashes due to the abnormality of the selected DNS server;
5. Perfect protocol stack: The new system is loaded with a perfect TCP/IP protocol stack. The original system uses a lightweight TCP/IP (LPIP) protocol stack, which is tailored. The new system uses a perfect TCP/IP protocol stack, which has excellent network communication performance;
6, EMC performance is excellent: through the power 3000 V electric shock test, especially suitable for use in the harsh industrial environment, the system is stable and reliable;
7. Multi-center support: The customer data can be sent to the monitoring center designated by the customer at the same time, and the maximum number of sending centers supported is 256.
The modem has a wide range of functions, and its core functions are as follows:
1. TCP/IP protocol stack is integrated inside
The modem encapsulates the PPP dial-up protocol and TCP/IP protocol stack and has an embedded operating system. From the hardware configuration, it can be regarded as the integration of embedded PC and wireless modem. It has the performance of 4G dial-up Internet access and TCP/IP data communication.
2. Provide bidirectional conversion performance for serial port data
Serial communication interfaces are given to modem, including RS232, RS485, RS422 and so on, which should be common forms of serial communication, and most of the serial data in modem are formulated in the form of "transparent conversion". That is to say, GPRSmodem can convert the original data on the serial port into TCP/IP data packets to complete the transmission without changing the inherent data communication content. Therefore, the modem can be connected with various user facilities using serial port communication without modifying the user facilities.
3. Compatible with self-heartbeat to ensure permanent online
One of the advantages of the 4G communication system is that it is compatible with the permanent online performance of 4G terminal equipment, so the typical modem is compatible with the permanent online performance, which requires the modem to include power-on automatic dialing and the use of heartbeat packets to ensure permanent online (when there is no data communication for a long time, the mobile gateway will disconnect the connection between the modem and the center. The heartbeat packet is a small data packet uploaded by the modem and the data center before the connection is disconnected to ensure that the connection is not disconnected), compatible with the features of automatic reconnection and automatic redialing.
4. Applicable parameter configuration, permanent storage
As a kind of communication equipment, modem is widely used. In different applications, the IP address and port number of the data center and the baud rate of the serial port are all different. Therefore, the modem should be compatible with the parameter configuration, and the equipped parameters should be stored in the permanent memory device (usually FLASH or EEPROM, etc.). If it is powered on, it will complete the work according to the set parameters.
5. Compatible with user serial port parameter settings
Different user facilities have different serial port parameters. When the modem is connected to the serial port of the user facility, it is necessary to complete the corresponding settings for the modem end according to the actual parameters of the serial port of the user facility, so as to ensure the normal communication and reliable data transmission of the user facilities.
Most of them are connected by modem and field equipment, such as PLC, SCM and other automation equipment. In addition, they are connected by wireless network communication with cloud platform. With the rapid development of the Internet, the use of modem is becoming more and more widespread. It helps the data information and industrial integration of various industries and industries. It has also gradually developed into the key core technology of the Internet of Things.