TCP/ip connect and maintain connection

[Azar]

Just add a if condition like this:

Code:

if previousvalue ~= value then
  -- send command
  sock:send (command)
  previousvalue == value
end

But if the value is not change often i would make it event based, initiate the connection, write the command and close the connection..

I've decided to go to an event script but cant get this to work.
Event script by Keyword: Symetrix.
all GA's with keyword "Symetrix" also have there control comand number assigned to them by keyword " SYM=### " I'm trying to get the script to insert the control number into the "CS" Command Send line .
I'm getting a log of

 * string: Error: sym=address tag missing

Code:

    local value = event.getvalue()
    local dest = event.dst

    local grps = GetCBusByKW('Symtrix', 'or')
    local k, v, alias, net, app, group
    local addr = ''
    local buffer = {}
log(grps)
    for k, v in pairs(grps) do
      alias = table.concat(v.address, '/')
      if alias == dest then
        local tags = v.keywords
     --log(tags)
        local t
        for _, t in ipairs(tags) do
          local tp = string.split(t, '=')
          tp[1] = trim(tp[1])
          if tp[2] then
            tp[2] = trim(tp[2])
            if tp[1] == 'sym' then
              addr = tp[2] -- Get device address
              break
            end
          end
        end
        break
      end
    end

    if addr ~= '' then
      -- create tcp socket
      local sock = require('socket').tcp()
      sock:settimeout(1)
      local connected, err = sock:connect('192.168.1.246', 48631)

      -- connect ok
      if connected then
        alert('[tcp-sock] connection ok')
      -- error while connecting
      else
        log('[tcp-sock] connection failed: '..err)
        sock:close()
        do return end
      end

      local command = 'CS '..addr..' '..(value * 257).. '\r'

      -- send command
      sock:send (command)

      local sent = socket.gettime()
      local timeout = 5

      while true do
        char, err = sock:receive(1)

        -- error while receiving, timeout or closed socket
        if err then
          -- remote server closed connection
          log('[tcp-sock] connection closed'..err)
          break
        -- end of line, parse buffer
        elseif char == '\r' then
          local data = table.concat(buffer)
          log(data)
          break
        -- other char, add to buffer
        else
          buffer[ #buffer + 1 ] = char
        end

        if socket.gettime() - sent > 5 then
          log('Timeout receiving data')
          break
        end
      end
      sock:close()
    else
      log('Error: sym=address tag missing')
    end