Description

This example shows the how to write or read to any XCON(TCP/UDP) connection. The connection can be handled with LUA function. The write value can be written from any selected item, and the read value also be written to an output item.
The Read function should handle the incoming values and convert them to their HEX values. 
This tutorial has two functions: 

• Send_TcpHex(): used to send HEX values of an Item in this example : ('NETx\\VAR\\String\\Item001') to the Server which has IP address : 127.0.0.1 and Port : 23. More info about xcon.SendHex
• MyTCP_OnReceiveEvent(data, size, sourceip, sourceport): This function is invoked when an XCON connection has been established. Create a function for each connection to monitor and name it accordingly, e.g. for connection "MyTCP"create the functionMyTCP_OnReceiveEvent.

function OnStartEvent() --this is a predefined function, add only the following line to the function.
	xcon.CreateTCP("MyTCP","0",0,"127.0.0.1",23) --Remote Server:127.0.0.1, Remote Port:23
end


function Send_TcpHex()
	local var = nxa.GetValue('NETx\\VAR\\String\\Item001') --Send value NETx\VAR\String\Item001
	xcon.SendHex("MyTCP", var)
end


function MyTCP_OnReceiveEvent(data, size, sourceip, sourceport)
	local val= string.tohex(data)
	nxa.SetValue('NETx\\VAR\\String\\Item002',val) --Received value NETx\VAR\String\Item002
end

function string.tohex(str)
    return (str:gsub('.', function (c)
        return string.format('%02X', string.byte(c))
    end))
end

Now o use this in LUA,  you can define a server task that is connected to the :('NETx\\VAR\\String\\Item001') item – this means when you want to send data, your LUA Function is invoked and you can parse and send data to the server.