Checksum XOR 4 bytes - Printable Version

Code:

addr = {'0x01','0x03','0x05','0x07','0x09','0x0b','0x0d','0x0f','0x11','0x13','0x15','0x17','0x19','0x1b','0x1d','0x1f','0x21'}
checksum = {'0xd3','0xd1','0xd7','0xd5','0xdb','0xd9','0xdf','0xdd','0xc3','0xc1','0xc7','0xc5','0xcb','0xc9','0xcf','0xcd','0xf3'} 
for i=1,17,1 do
   command = string.char(0x04,0x04,addr[i],0xd2,checksum[i]) 
   reply = writetoport(port, 0.2, command)
   decoded = str2hex(reply)
   log('Device address: eA'.. i-1 .. ', Result: ' .. decoded)
end

Code:

function encode(...)
  local checksum = bit.bxor(...)
  return string.char(...) .. string.char(checksum)
end

addrs = {0x01,0x03,0x05,0x07,0x09,0x0b,0x0d,0x0f,0x11,0x13,0x15,0x17,0x19,0x1b,0x1d,0x1f,0x21}

for _, addr in ipairs(addrs) do
  command = encode(0x04,0x04,addr,0xd2) 
  reply = writetoport(port, 0.2, command)
  decoded = str2hex(reply)
  log('Device address: eA'.. i-1 .. ', Result: ' .. decoded)
end

Code:

if not port then
require('serial')
    port, err = serial.open('/dev/RS232', {baudrate = 38400, databits = 8, stopbits = 1, parity = 'none', duplex = 'full'})
    if port then
    port:flush()
  else
    log('Error open port in: ' .. err)
  end
end

function readline(port, timeout) 
  local char, buf 
  buf = {} 
  while true do 
    char = port:read(1, timeout or 0.2) 
    if char == nil or char == '\n' then 
      break  
    elseif char ~= '\r' then 
      table.insert(buf, char) 
    end 
  end 
  return table.concat(buf) 
end 

function writetoport(port, timeout, command) 
  port:write(command) 
  line = readline(port, timeout)
  if #line > 0 then
      return line
  else
    return "No reply received"
  end
end

function str2hex(str)
    raw_len = string.len(str)
    i = 1
      value = ''
  while i <= raw_len do
    if value then
      if i == 4 then
              value = string.byte(str, i)
      end
    else
      value = string.byte(str, i)
    end
    i = i + 1
  end 
  return value
end

function encode(...)
  local checksum = bit.bxor(...)
  return string.char(...) .. string.char(checksum)
end

addrs = {0x01,0x03,0x05,0x07,0x09,0x0b,0x0d,0x0f,0x11,0x13,0x15,0x17,0x19,0x1b,0x1d,0x1f,0x21,0x23}

local sum = 0

for _, addr in ipairs(addrs) do
  command = encode(0x04,0x04,addr,0xc8)
  reply = writetoport(port, 0.1, command)
  decoded = str2hex(reply)
  if grp.getvalue('37/3/'.. sum)~=decoded then
        grp.update('37/3/'.. sum, decoded)
  end
  sum = sum + 1
end

value = event.getvalue()
if value == true then
    grp.update(event.dst, false)
elseif value == false then
    grp.update(event.dst, true)
end