function readRegister (reg, device, unitId)
   
   if not carel.synced then 
                                            DEBUG("Trying to sync, packet #1...")
       local newId = unitId + ADDR_OFFSET
       carel.pollTemplate[2] = newId
       
       makeSync(carel.syncTemplate, newId)
       local reply = readUntil(ETX, true)
       
       if reply then
           hexPrint(reply)
           if (#reply > 30) then 
               DEBUG("Sync 1 done!")
               -- now 2nd sync 
               makeSync(carel.sync2_Tmpl, newId)
               reply = readUntil(ACK, false)
               if reply then 
                   hexPrint(reply)       ; DEBUG("sync 2 ok!")
                   carel.synced = true 
               end 
           end 
        end 
   end 
   
   if carel.synced then  -- synced 
      local poll_counter, POLL_LIMIT = 0, 40
      
      repeat 
          poll_counter = poll_counter + 1 
          sendBytes(carel.pollTemplate) ; local reply = readUntil(ETX, true)
          
          if not reply then 
              ERROR("could not receive reply from device...")
              carel.synced = false 
              return false 
          end 
          
          if (reply[1] == NULL) then 
                                            DEBUG("Got NULL! - no changes")
              sendBytes{ACK}                                
              break 
          else
                                            DEBUG("Normal sequence, got something!")
              sendBytes{ACK}

              local idx = {type = 3, addr_hi = 4, addr_lo = 5, data_start = 6}
              local type_ = string.char(reply[idx.type]) ; DEBUG("type = " .. type_)
              if not (type_ == 'B' or type_ == 'U' or type_ == 'S') then 
                                            ERROR("Unknown type of the device!")
                  return -1
              else 
                  local dev_addr = getHexFromASCII(reply[idx.addr_hi], reply[idx.addr_lo])
                  dev_addr = string.sub(dev_addr, 1, -2)
                  dev_addr = tonumber(dev_addr, 16) ; DEBUG("dev_addr detected = " .. dev_addr)
                  
                  local dev_data_len = ((type_ == 'B' and 2) or 4)
                  
                  local tmp_t = {}
                  for j = idx.data_start, idx.data_start + dev_data_len - 1 do 
                      table.insert(tmp_t, string.char(reply[j]))
                  end 
                  local dev_data = tonumber(table.concat(tmp_t), 16) 
                  DEBUG('dev type  addr data = ' .. type_ .. ' ' .. sf("%X", dev_addr) .. ' ' .. sf("%X", dev_data))
                  
                  carel.data[type_][dev_addr] = dev_data
              end 
        end 

      if (poll_counter >= POLL_LIMIT) then 
         DEBUG("Poll counter finish!")          
      end 
      until (poll_counter >= POLL_LIMIT)
    
    local value = carel.data[device.name][reg.internalAddr]
    return value 
  
   end -- synced 
end -- readRegister