Description

This example shows the how to write to and or read to any from an XCON (TCP/, UDP, etc.) 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 read function should handle handles the incoming values and convert them to their HEX values. converts them into a hex dump string.

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

   This callback function is invoked when an XCON connection has been established.

  Create

  Implement a callback function for each connection to monitor and name it accordingly, e.g. for connection

  "MyTCP"create the functionMyTCP

  named MyTCP implement the callback function MyTCP_OnReceiveEvent().

LUA

function OnStartEvent() -- this is a predefined callback function, add only the following linesline to the function.

local var = nxa.GetValue('NETx\\VAR\\String\\Item001')
	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

...

Next, define a server task that is connected to the :('triggerd upon changes of the source item, NETx\\VAR\\String\\Item001') item – this means when you want  – That is, to send data , your the LUA Function is invoked and you can parse and send data for the server. 

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Image Removedfunction is invoked: the source item value is treated as a hex dump string, converted into binary data and sent to the connection.

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