the average value of tagged objects

Code:
if not client then
  -- each group has 3 fields:
  -- tag - status object tag
  -- output - status output object
  -- mode - calculate mode (and/or/avg)
 
  groups = {
    { tag = 'vnt251', output = '6/2/51', mode = 'or' },
    { tag = 'vnt252', output = '6/2/52', mode = 'or' },
    { tag = 'vnt254', output = '6/2/54', mode = 'or' },
    { tag = 'vnt150', output = '6/1/50', mode = 'or' },
    { tag = 'vnt152', output = '6/1/52', mode = 'or' },
    { tag = 'vnt153', output = '6/1/53', mode = 'or' },
  }
  
  
  -- time to wait between last telegram from any status in group and update
  updatedelay = 0.5

  timeout = updatedelay / 2

  -- object value cache
  values = {}

  -- object datatype cache
  datatypes = {}

  -- send update only when value changes
  grp.checkupdate = function(alias, value)
    if values[ alias ] ~= value then
      grp.update(alias, value)
    end
  end

  calc = {}

  -- AVERAGE value
  calc['avg'] = function(group)
    local result, count, value = 0, 0

    for _, address in ipairs(group.objects) do
      value = values[ address ]

      -- number must be in [0..100] range
      if type(value) == 'number' then
        result = result + value
        count = count + 1
      -- boolean true is 100%, false is 0%
      elseif type(value) == 'boolean' then
        if toboolean(value) then
          result = result + 100
        end

        count = count + 1
      end
    end

    if count > 0 then
      result = math.floor(result / count + 0.5)
      grp.checkupdate(group.output, result)
    end
  end

  -- AND gate
  calc['and'] = function(group)
    local result = true

    for _, address in ipairs(group.objects) do
      result = result and toboolean(values[ address ])
    end

    grp.checkupdate(group.output, result)
  end

  -- OR gate
  calc['or'] = function(group)
    local result = false

    for _, address in ipairs(group.objects) do
      result = result or toboolean(values[ address ])
    end

    grp.checkupdate(group.output, result)
  end

  -- MAX value
  calc['max'] = function(group)
    local result = -math.huge

    for _, address in ipairs(group.objects) do
      local value = values[ address ]

      if type(value) == 'number' then
        result = math.max(result, value)
      end
    end

    grp.checkupdate(group.output, result)
  end

  -- MIN value
  calc['min'] = function(group)
    local result = math.huge

    for _, address in ipairs(group.objects) do
      local value = values[ address ]

      if type(value) == 'number' then
        result = math.min(result, value)
      end
    end

    grp.checkupdate(group.output, result)
  end

  -- SUM value
  calc['sum'] = function(group)
    local result = 0

    for _, address in ipairs(group.objects) do
      local value = values[ address ]

      if type(value) == 'number' then
        result = result + value
      end
    end

    grp.checkupdate(group.output, result)
  end

  -- prepare each group
  for _, group in ipairs(groups) do
    object = grp.find(group.output)

    -- cache output status object value and datatype
    values[ object.address ] = object.data
    datatypes[ object.address ] = object.datatype
    group.output = object.address

    -- group input status object list
    group.objects = {}

    -- find all status objects and cache values and datatypes
    objects = grp.tag(group.tag)
    for _, object in ipairs(objects) do
      values[ object.address ] = object.data
      datatypes[ object.address ] = object.datatype
      table.insert(group.objects, object.address)
    end

    -- force update on first run
    group.timer = 0

    -- calc function reference
    group.fn = calc[ group.mode ]
  end

  -- handle group writes
  function eventhandler(event)
    local dst, datatype

    dst = event.dst
    datatype = datatypes[ event.dst ]
    -- unknown object, stop
    if not datatype then
      return
    end

    values[ dst ] = dpt.decode(event.datahex, datatype)

    -- check if any group needs to be updated
    for _, group in ipairs(groups) do
      for _, address in ipairs(group.objects) do
        if address == dst then
          group.timer = updatedelay
        end
      end
    end
  end

  require('genohm-scada.eibdgm')
  client = eibdgm:new({ timeout = 0.1 })
  client:sethandler('groupwrite', eventhandler)
end

delta = 0
repeat
  tsec, tusec = os.microtime()
  client:step()
  tdelta = os.udifftime(tsec, tusec)

  -- clock jump
  if tdelta < 0 then
    delta = timeout
  else
    delta = delta + tdelta
  end
until delta >= timeout

-- check if any group has an active timer
for _, group in ipairs(groups) do
  timer = group.timer

  if timer then
    timer = timer - delta

    -- timer expired, run calc function
    if timer <= 0 then
      group.fn(group)
      timer = nil
    end

    group.timer = timer
  end
end