Example: LM2 as TCP server for external requests

Task

On each value change for object ’1/1/1′, send TCP messages to all connected external TCP clients.

UDP client function

The following function has to be added into Scripting -> Tools -> User function library.
It will forward each message received to UDP server which will send it to all connected TCP clients.

  1. function udpsend(message)
  2.   require('socket')
  3.  
  4.   local client = socket.udp()
  5.   -- upd client ready, send to local port 23456
  6.   if client then
  7.     client:sendto(message, '127.0.0.1', 23456)
  8.     client:close()
  9.   end
  10. end

Resident script – server handler

Add the following resident script with Sleep interval 0.
It defines TCP server and UDP server. Connection can be established when TCP client sends message “HELLO”, TCP server/LM2 will respond with “HELLO YOU TOO”.

  1. -- init server handler
  2. if not ready then
  3.   require('copas')
  4.  
  5.   -- list of client sockets
  6.   clients = {}
  7.  
  8.   -- incoming data handler
  9.   function datahandler(sock, data)
  10.     local ip, port
  11.     ip, port = sock:getpeername()
  12.     alert('[server] data from %s:%d - %s', ip, port, data)
  13.  
  14.     -- send reply
  15.     if data == 'HELLO' then
  16.       sock:send('HELLO TO YOU\r\n')
  17.     end
  18.   end
  19.  
  20.   -- connection handler
  21.   function connhandler(sock)
  22.     -- enable keep-alive to check for disconnect events
  23.     sock:setoption('keepalive', true)
  24.  
  25.     local ip, port, data, err, id
  26.  
  27.     -- get ip and port from socket
  28.     ip, port = sock:getpeername()
  29.  
  30.     -- client id
  31.     id = string.format('%s:%d', ip, port)
  32.  
  33.     alert('[server] connection from %s', id)
  34.  
  35.     -- save socket reference
  36.     clients[ id ] = sock
  37.  
  38.     -- main reader loop
  39.     while true do
  40.       -- wait for single line of data (until \n, \r is ignored)
  41.       data, err = copas.receive(sock, '*l')
  42.  
  43.       -- error while receiving
  44.       if err then
  45.         alert('[server] closed connection from %s:%d', ip, port)
  46.         -- remove socket reference
  47.         clients[ id ] = nil
  48.         return
  49.       end
  50.  
  51.       -- handle data frame
  52.       datahandler(sock, data)
  53.     end
  54.   end
  55.  
  56.   -- bind to port 12345
  57.   tcpserver = socket.bind('*', 12345)
  58.  
  59.   -- error while binding, try again later
  60.   if not tcpserver then
  61.     os.sleep(5)
  62.     error('[server] error: cannot bind')
  63.   end
  64.  
  65.   -- set server connection handler
  66.   copas.addserver(tcpserver, connhandler)
  67.  
  68.   -- create local udp server on port 23456
  69.   udpserver = socket.udp()
  70.   udpserver:setsockname('127.0.0.1', 23456)
  71.   udpserver:settimeout(0.1)
  72.  
  73.   ready = true
  74. end
  75.  
  76. -- perform server tasks for one second (5 x (0.1 + 0.1))
  77. for i = 1, 5 do
  78.   message = udpserver:receive()
  79.  
  80.   -- got message from udp, send to all active clients
  81.   if message then
  82.     for id, sock in pairs(clients) do
  83.       sock:send(message .. '\r\n')
  84.     end
  85.   end
  86.  
  87.   copas.step(0.1)
  88. end

Event-based program

Event-based script will monitor the object ’1/1/1′, if it is switched on, “Lamp is ON” is sent to all TCP clients currently connected to Logic Machine 2 TCP server, if lamp is switched off – “Lamp is OFF”.

  1. value = knxdatatype.decode(event.datahex, dt.bool)
  2. udpsend('Lamp is' .. (value and 'ON' or 'OFF'))