NB-IoT (Narrow Band Internet of Things, NB-IoT) is an emerging technology of the cellular-based narrowband Internet of Things in the IoT field. It supports the cellular data connection of low-power devices in the wide area network. It is also called low-power wide area network ( LPWA).

The Internet of Things connects all the machines and equipment on the production line. Users can view the status of the equipment and production progress anywhere, providing mobile users with real-time manufacturing data. However, as more and more devices are connected to the Internet and a large amount of data is transmitted, a lot of pressure is placed on the network and cloud systems. In order ···

When the communication distance is tens of meters to thousands of meters, the RS-485 serial bus standard is widely used. RS-485 uses balanced transmission and differential reception, so it has the ability to suppress common mode interference. The standard value of the maximum transmission distance of the RS-485 interface is 4000 feet (about 1219 meters), which is actually up to 3000 meters. In add···

COM口是串行通信端口，简称串口。一般来说，我们看到两个物理标准。D型9针插头，加4针杜邦排针，是USB转TTL串口的小板，可通过USB进行扩展。对于使用不带COM的笔记本电脑或台式电脑的嵌入式工程师来说，它是必不可少的工具。除了使用串口向单片机下载程序外，它也是辅助调试程序的神器。

Modbus网关可以称为以太网通信网关，它可以实现Modbus RTU/ASCII和Modbus TCP协议之间的转换。Modbus协议分为两种，一种是基于RS485的Modbus RTU(或ASCII)协议，另一种是基于以太网的Modbus TCP协议。Modbus网关是将Modbus RTU设备数据转换为Modbus TCP数据的转换器。

Design features of NB-IoT network:Ultra-low power consumption: With the addition of the PSM function, the current consumption of the terminal in this mode is about 3uA, even if the dry battery is used, the module can be driven for 10 years;

NB-IoT协议是一套无线蜂窝网络通信规则，旨在充分利用宝贵的无线频谱资源和时间资源来满足LPWA的需求。它的作用是制定一套用于信息交互的语法、语义和时序。简而言之，就是规则规定了交流参与者使用什么语言、意思是什么、谁说谁听、说多长时间。

LoRa主要运行在全球免费频段（即免授权频段），包括433、868、915 MHz等。LoRa网络主要由四部分组成：终端（内置LoRa模块）、网关（或基站）、服务器和云。LoRa应用数据可以双向传输。

LoRa技术要点:一般来说，传输速率、工作频段和网络拓扑是影响传感器网络特性的三个主要参数。传输速率的选择会影响系统的传输距离和电池寿命；工作频段的选择应兼顾频段和系统的设计目标；而在FSK系统中，网络拓扑的选择是由传输距离要求和系统所需的节点决定的。数量已确定。LoRa集成了数字扩频、数字信号处理和前向纠错编码技术，具有前所未有的性能。此前，只有那些高水平的工业无线电通信才会集成这些技术，随着LoRa的引入，

LoRa主要在全球免费频带(即免牌频带)内运作，包括433、868、915兆赫等。LoRa网络主要由终端(内置LoRa模块)、网关(或基站)、服务器和云四部分组成。LoRa应用数据可以双向传输。