1.What’s upper computer and lower computer?

Upper computer and lower computer is a relative concept, in communication area, if there is a pair of devices with a master-slave relationship, the terminal device responsible for submitting information is the lower computer, and the device responsible for processing the submitted data is the upper computer. In most cases, DTU equipment belongs to lower computer, data center responsible for processing DTU returned information is upper computer, typical application method is that multiple DTUs correspond to one data center. However, upper computer and lower computer isn’t a must to have one-to-one correspondence, one lower computer may correspond to one or more upper computers, one upper computer may correspond to one or more lower computers, specific corresponding method subject to specific application.

2.What’s data center?

Data center refers to upper computer system that collects, summarizes and processes the information returned by the lower computer, controls and manages the lower computer to a certain extent, it includes complete computer hardware equipment and specific complete software functions.

3.What’s fully transparent transmission?

Fully transparent transmission means no operations or changes are made to the IP packets, just a simple sending process. There is no change for format and content of the data before sending and after receiving during fully transparent transmission process, the data received by the remote data center is the same as the data collected on site, if there is any operations or changes on the IP packet, it will not be fully transparent in the full sense.

4.What’s the difference between DTU and wireless modem?

Firstly have to clarify that DTU is quote different from modem.

DTU encapsulates the content of the protocol stack and has an embedded operating system in software design, it can be regarded as the combination of an embedded PC and a wireless access part from hardware angle.

GPRS/4G Modem is a physical channel connected to GPRS/4G packet network, it does not have an operating system itself so have to attach to a computer (similar to a wired Modem), can only make PPP dial-up connection with computer operating system,  usually used in conjunction with a PC.

DTU is a combination of an embedded PC and a GPRS/4G Modem from a certain perspective, but it cannot be used as a modem alone, it completes the functions of data protocol conversion and transparent transmission.

In terms of use, front-end collection equipment or intelligent data equipment usually provides standard data interfaces, such as RS232, RS485/422, etc., these front-end users suitable for using DTU to realize data communication with monitoring center with the help of GPRS/4G network platform. GPRS/4G Modem needs to be connected to a computer to achieve network connection, for example, the PC host of the central station can connect GPRS/4G network through GPRS/4G Modem to form a central station server to achieve network monitoring, data communication etc.. But DTU is difficult to be used as a central service station.

5.What preparations are needed before DTU testing?

1.A public IP address or independent domain name

In some cases, computers haven’t independent public IP addresses and domain name addresses because they are in an internal LAN, in this case, you have to dial-up internet access to obtain an independent public IP address, or you can set up a DMZ host mapping or port mapping in the router so that the computer can penetrate intranet to communicate with DTU.

2.A SIM card enabled for GPRS data service (it is must for testing GPRS DTU), or a UIM card enabled for 4G data service (it is must for testing 4G DTU).

3.A desktop computer or laptop with a 9 Pin RS232 serial port

This computer is used to set and adjust the parameters of the DTU. In the meantime, DTU can be connected as a virtual data source device, data can be sent and received with the host computer data center through the serial port debugging tool. Of course, if computer meets condition 1, it can be both host computer data center and virtual data source slave computer. But for the second purpose of testing, try to avoid doing this to avoid doubting the test itself.