DTU Detailed explanation of 4G DTU working principle and test steps

Working principle of Jrepus 4G DTU is connected with hydrology, electricity, meteorology, environmental protection and other equipment and placed on site. After the DTU is powered on, it first registers with the network service provider, and then sends a SOCKET request packet to the network service provider, and the network service provider sends the request to the Internet.

After receiving the request, the server software of the center establishes a connection and sends a response message. The request information sent by DTU is a data packet on the Internet. There are some reasons that will prevent the center from receiving the connection request packet, so that the connection cannot be established. The most common computer with the center has anti-virus software, firewall, etc. to shield these data packets. The other is that the central computer accesses the Internet through a router, and data forwarding must be set on the router. After the SOCKET connection is established, two-way communication is possible.

4G DTU test use steps detailed explanation：

1. Test network topology:

After the DTU configures various parameters through the serial port, the core parameters are the public IP and port of the server. After the configuration is saved, the DTU will dial and connect to the saved public IP and port of the server, and connect to the server software. After uploading, DTU and server software can communicate.

Remarks: For the convenience of testing or if conditions do not permit, the PC for configuring DTU and the server PC can be the same. Because the configuration of the DTU is through the serial port, and the server simulation software is through the network port, the PC can be used at the same time.

2. Server network configuration instructions

DTU needs to rely on the public network IP and port of the server to establish a connection. Therefore, you must first know the public network IP of the server, and then configure the port. By logging into the router of the server PC, you can know the public network IP and do port mapping.

Query the public network IP:

On the status query page of the router, you can see the external network IP of the router, which should be the public network IP.  

Remember this public network IP, and then make a port mapping on this router to the IP of the PC where the server software is located. 

Port Mapping:  

Port mapping is generally done under the NAT function/port forwarding/forwarding rules of the router. Taking the Jrepus router as an example, if the IP of the PC where the server software is located is 192.168.10.109, the port to be configured is 9256.

3. DTU configuration instructions

The DTU is mainly responsible for dialing up the Internet, establishing a connection with the server software through the operator's wireless network, and establishing a transparent "communication bridge" between the lower computer and the server software. Therefore, the core configuration parameters are mainly communication-related server IP, port and serial port parameters. (It is already known that the public network IP of the server is 27.154.58.226, and port 9256 is configured to the server PC. This is an example configuration DTU communication)

Description of core configuration parameters:

3.1 Central server parameter configuration  The maximum number of servers can be set to 5.  

3.2 DTU working parameter configuration.

Note: Description of each working mode of DTU

PROT mode TCP transmission protocol mode with fixed registration packets and heartbeat packets;  

DCTCP mode Power-related communication protocol, using TCP protocol for transmission;  

DCUDP mode Power-related communication protocol, using TCP protocol for transmission;  

TRNS mode modem mode;  

In SMSCLI mode, the 4G DTU is used as a SMS DTU, and the work data is sent to the bound mobile phone through SMS, and at the same time, it receives the content sent by the bound mobile phone, and sends the data to the designated peripheral interface;

The 4G DTU in SMSSER mode is used as a SMS DTU, and the work data is sent to the bound mobile phone by SMS, but there are requirements for the content to be sent, and it must be sent in frames according to the specified format. At the same time, the mobile phone can send data to the SMS DTU, and the SMS DTU The data will be sent to the specified peripheral interface;

4. DTU communicates with the center

After configuring the server's network and DTU parameters, start the server software monitoring port on the server side, and the DTU configuration software can click "Restart the device to enter the communication state" to connect, and the two parties have established communication.

5. Server dynamic public network IP environment  

Jrepus DTU supports the domain name resolution function, so when the public network IP of the server is dynamic (such as PPPoE dial-up mode), the server can use DDNS (Dynamic Domain Name Resolution) to replace the dynamic IP with a fixed domain name. Jrepus routers support DDNS function. For routers that do not support DDNS function, you can use peanut shells.