RFID reader integration over RS-232

[edgars]

The example below shows how to integrate Idesco Access 7 C RFID reader over RS-232 port. The script below will read all RFID cards and log IDs. The script is easy adjustable if there is a necessity to trigger specific KNX, Bacnet etc. objects.

Add the following resident script with sleep-time = 0:

Code:

-- init
if not port then
 require('serial')

 port = serial.open('/dev/RS232', { baudrate = 9600 })

 function readid(port)
   local char, byte, line, id, csum, val

   -- wait for start byte
   char = port:read(1, 1)
   if not char then
     return nil, 'timeout'
   end

   -- start byte must be STX
   byte = char:byte(1)
   if byte ~= 2 then
     return nil, 'wrong start byte'
   end

   -- read remaining line
   line = port:read(15, 1)
   if not line then
     return nil, 'failed to read data'
   end

   -- calculate checksum
   csum = 0
   for i = 1, 11 do
     val = tonumber(line:sub(i, i), 16)
     csum = bit.bxor(csum, val)
   end

   -- verify checksum
   if csum ~= tonumber(line:sub(12, 12), 16) then
     return nil, 'invalid checksum'
   end

   -- return ID
   return line:sub(1, 10)
 end
end

id = readid(port)
if id then
 log(id)
end