Hex manipulation

[Erwin van der Zwart]

Hi Buuuudzik,

Here is a script i use for other devices, here is a function to read a line without knowing the lenght, also another HEX function you might want to use:

Code:

---------------------------------------------------------------------
-- *********************** START CONNECTION ********************** --
---------------------------------------------------------------------

-- Load Modules
require('serial')

-- Open connection
port = serial.open('/dev/RS485', { baudrate = 4800, parity = 'odd', duplex = 'half', databits = 8, stopbits = 1 })

---------------------------------------------------------------------
-- *********************** START FUNCTIONS *********************** --
---------------------------------------------------------------------

-- Function to read until carier return is received or timeout
function readline(port, timeout)
 local char, buf
 buf = {}
 while true do
   char = port:read(1, timeout or 0.2)
   -- error (timeout) or newline, stop
   if char == nil or char == '\n' then
     break
   -- ignore cr char
   elseif char ~= '\r' then
     table.insert(buf, char)
   end
 end
 return table.concat(buf)
end

-- Function to write to port and return a reply
function writetoport(port, timeout, command)
    -- Write data to port as HEX
 port:write(command)
    -- Call function to read data
 line = readline(port, timeout)
 if #line > 0 then
     return line
 else
   return "No reply received"
 end
end

-- Function to decode hex string value to readable string format
function str2hex(str)
    raw_len = string.len(str)
    i = 1
 while i <= raw_len do
   current_hexvalue = '0x' .. string.format("%02x", string.byte(str, i))
   if value then
     value = value .. ', ' .. current_hexvalue
   else
       value = current_hexvalue
   end
   i = i + 1
 end
 return value
end

---------------------------------------------------------------------
-- ************************ END FUNCTIONS ************************ --
---------------------------------------------------------------------

---------------------------------------------------------------------
-- *********************** START WRITE/READ ********************** --
---------------------------------------------------------------------

-- Declare command to send to rotel
command = string.char(0xfe, 0x03, 0xa5, 0x10, 0x0a, 0xc2) -- power toggle

-- Send command to port and wait for reply or timeout
reply = writetoport(port, 1, command)-- Timeout is set to 1 second (default = 0.2)

---------------------------------------------------------------------
-- ************************ END WRITE/READ *********************** --
---------------------------------------------------------------------

---------------------------------------------------------------------
-- ************************ START LOGGING ************************ --
---------------------------------------------------------------------

-- Process the reply
if reply == "No reply received" then
 log(reply)
else
 --Decode the reply if hex
 decoded = str2hex(reply)
 log(decoded)
end
 
---------------------------------------------------------------------
-- ************************* END LOGGING ************************* --
---------------------------------------------------------------------

-- Close port
port:close()

---------------------------------------------------------------------
-- ************************ END CONNECTION *********************** --
---------------------------------------------------------------------

Hope this helps you..

BR,

Erwin