View source for NB-IoT UDP

==Introduction==
This test shows how to use the NB-IoT End Node to connect to the IoT Server via the most simple NB-IoT structure. 

The network structure is as below. The protocol used here is UDP protocol. 
[[File:NB-IoT_E_0.png|800px|none|thumb|Simple NB-IoT Structure]]

==Test introduce==
NB-IoT  carry out UDP protocol, the function of example realizes that NB-IoT  sent data to server and the server return the data to NB-IoT too.Therefore, the test was realized under LAN(local area network),at the moment,we should known the IP and port of LAN.

==Software in the IoT Server==
In the IoT Server, we should do below:
* Confirm if your server is reachable by the carrier.  For example, some carrier such as China Telecom require that your server is in their whitelist so they can transfer the data from their NB-IoT network to your server. While some carrier can transfer data to all ip. Please confirm first. 
* You need to run a application in your server to process the packet from your NB-IoT node (through NB-IoT Carrier network). 

In this example, we will show how to write a lua script to process the NB-IoT data, to test this example, you need to install lua and lua_socket in your server. 

Below is the lua script: 
<syntaxhighlight lang="lua">
-- upd-server Test
local socket = require "socket"

local port = 5683   -- Use UDP port 5683 to accept NB packet. 
local udp = socket.udp()
udp:settimeout(0)
udp:setsockname('*', port)    --server

local data, msg_or_ip, port_or_nil
local running = true

-- the beginning of the loop proper...
print "Beginning server loop."
while running do
    data, msg_or_ip, port_or_nil = udp:receivefrom()
    if data then
            print("udp:receivefrom: " .. data .. msg_or_ip, port_or_nil)    -- print it out if a packet arrive. 
            udp:sendto(data, msg_or_ip, port_or_nil)      -- Send back a message to NB-IoT network, the carrier will then forward this packet to the NB-IoT End node. 

            if data == "quit" then
                running = false
            end
    elseif msg_or_ip ~= 'timeout' then
        error("Unknown network error: "..tostring(msg))
    end

    socket.sleep(0.01)
end
</syntaxhighlight>
saving the file as UPD_server.lua,we input the command scan the file content.
<syntaxhighlight lang="lua">
cat UPD_server.lua
</syntaxhighlight>
[[File:udp1.jpg|600px|none|thumb|cat command]]

Then  run this file:
<syntaxhighlight lang="lua">
lua UPD_server.lua
</syntaxhighlight>

After that, the screen print"Beginning server loop."character string,it represents that server is ready to receive packet from the NB nodes

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==Code in the NB-IoT End Node==
The NB-IoT node we use here is NB-IoT Shield + UNO. the code is in [https://github.com/dragino/NB-IoT/tree/master/NB-IoT%20Shield/examples/nbiot_UDP this link]: 

User should change the udpserver address and port to the actual one.  
 const int port = 5683;                     //server port
 const char udpserver[] = "120.78.138.177"; // UDP server of dragino

The main most important code is : "bc95_serial.println(F("AT+NSOST=0,120.78.138.177,5683,3,616263"));",the numer "0" is represent UDP protocol,the "0,120.78.138.177" is IP of IoT Server,the number"5683" is server port, the number "3" represent sent data length is three bytes,the number"616263"is hex data,represent is "abc".
[[File:udp7.jpg|600px|none|thumb|program]]


Upload this code to UNO, and open the serial port scan,now ,we should see the server receive the data,the picture follow as:
[[File:udp8.jpg|600px|none|thumb|Result in Server Side]]
finally, we look for client receive data form server,the picture follow as:
[[File:udp9.jpg|600px|none|thumb|Output in NB-IoT Shield]]