1.Internal integrated TCP/IP protocol stack
GPRS modem internally encapsulates the PPP dial-up protocol and the TCP/IP protocol stack and has an embedded operating system. From the hardware, it can be seen as a combination of embedded PC and wireless GPRS MODEM; it has GPRS dial-up Internet access and TCP/IP data communication.
2.Provide serial data bidirectional conversion function
GPRS modem provides serial communication interface, including RS232, RS485, RS422, etc., which are all commonly used serial communication methods. Moreover, most of the GPRS modems design the serial port data into a "transparent conversion" mode, which means that the GPRS modem can convert the original data on the serial port into TCP/IP data packets for transmission without changing the original data communication content. Therefore, the GPRS modem can be connected to various user equipment that use serial communication, and there is no need to change the user equipment.
3.Support automatic heartbeat, stay permanent online
One of the advantages of the GPRS communication network is that it supports the GPRS terminal device to be permanently online, so the typical GPRS modem is designed to support the permanent online. This requires the modem to include automatic power-on dialing and use the heartbeat packet to stay permanently online (when there is no data communication for a long time, the mobile gateway will disconnect the modem from the center, and the heartbeat packet is a small data packet send before the connection between the modem and the data center is disconnected so as to keep the connection from being disconnected), support automatic re-connection after disconnection, automatic redialing and so on.
4.Support parameter configuration, permanent save
As a communication device, the GPRS modem has a wide range of applications. In different applications, the IP address and port number of the data center, the baud rate of the serial port, etc. are all different. Therefore, the GPRS modem shall support parameter configuration, and save the configured parameters in the internal permanent storage device (generally FLASH or EEPROM, etc.). Once powered, it automatically works according to the set parameters.