M-Bus (Meter-Bus) library and examples

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The script only handles cases when a single value is needed from each meter. It can be modified like this to be able to specify group address for each meter entry:

Code:

-- config init
if not meters then
  require('mbus')

  -- time to wait between each meter read
  sleeptime = 10
  -- use /dev/RS232 serial port with 2400 baud rate
  mbus.init('/dev/RS232', 2400)
  -- base address for meter values, meter short address will be added to form the meters group address
  base = '2/1/'

  -- meter definition
  -- addr - short address
  -- id - number from data table where value resides
  -- div - optional divisor for conversion to the final value
  meters = {
    { addr = 1, id = 2, div = 1000, groupaddr = '1/1/1' }, -- hot water meter, convert from m3 to liters
    { addr = 2, id = 2, div = 1000, groupaddr = '1/1/2' }, -- cold water meter, convert from m3 to liters
    { addr = 3, id = 5, groupaddr = '1/1/3' }, -- heating meter 1
    { addr = 4, id = 5, groupaddr = '1/1/4' }, -- heating meter 2
  }

  -- reset meter values on first run
  for _, meter in ipairs(meters) do
    meter.value = 0
  end
end

-- read each meter
for _, meter in ipairs(meters) do
  res = mbus.getdata(meter.addr)

  -- read ok
  if type(res) == 'table' then
    data = res.data[ meter.id ]
    value = nil

    -- get current value
    if type(data) == 'table' then
      value = tonumber(data.value)
    end

    -- value is valid and different from previous read
    if value and meter.value ~= value then
      -- apply divisor if set
      div = meter.div
      dpt = div and dt.float32 or dt.uint32
      if div then
        value = value / div
      end

      -- update group address value
      addr = meter.groupaddr or (base .. tostring(meter.addr))
      grp.update(addr, value, dpt)
      meter.value = value
    end
  end

  -- wait for next read
  os.sleep(sleeptime)
end