Serial Communication
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Serial Communication |
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-- Lua serial communications library. -- -- Note: currently only works on Win32. -- -- The implementation uses alien ( http://alien.luaforge.net/ ). -- -- Warning: not extensively tested. -- -- Possible improvements: -- - decide more consistently when to raise or return on error -- (io.open/fh:read/fh:write return, but Lua -- Programming Gems, p.137 suggests we perhaps -- should raise) -- - add close() method on file handle, possibly -- via __gc on newproxy() so that it closes upon -- garbage collection -- -- D.Manura. 2008-07 -- S.Slobodov, 2009-01: fixed alien interface, fixed a typo, -- added COM10 and up, made non-blocking -- D.Manura, 2009-01: add close(); improve exception safety some -- S.Slobodov, 2009-01: added routines to set DTR and RTS and to query CTS, plus unbuffered transmission -- Licensed under the same terms as Lua itself (MIT license). -- Please post patches and improvements. local M = {} local alien = require "alien" -- win32 values for CreateFile local GENERIC_READ = 0x80000000 local GENERIC_WRITE = 0x40000000 local OPEN_EXISTING = 3 -- win32 parity values local EVENPARITY = 2 local MARKPARITY = 3 local NOPARITY = 0 local ODDPARITY = 1 local SPACEPARITY = 4 -- win32 stop bit values local ONESTOPBIT = 0 local ONE5STOPBITS = 1 local TWOSTOPBITS = 2 -- maps parity name to win32 parity value local parity_to_win32 = { even = EVENPARITY, mark = MARKPARITY, none = NOPARITY, odd = ODDPARITY, space = SPACEPARITY } -- maps stop bits to win32 stop bits value local stopbits_to_win32 = { [1] = ONESTOPBIT, [1.5] = ONE5STOPBITS, [2] = TWOSTOPBITS } local kernel32 = alien.load"kernel32.dll" -- bitwise operators -- based on http://ricilake.blogspot.com/2007/10/iterating-bits-in-lua.html -- 1-based indexing local function bit(p) return 2 ^ (p - 1) end local function hasbit(x, p) return x % (p + p) >= p end local function setbit(x, p) return hasbit(x, p) and x or x + p end local function clearbit(x, p) return hasbit(x, p) and x - p or x end local function changebit(x, p, b) return b and setbit(x,p) or clearbit(x,p) end local function get_last_error() local FORMAT_MESSAGE_ALLOCATE_BUFFER = 0x00000100 local FORMAT_MESSAGE_FROM_SYSTEM = 0x00001000 local FORMAT_MESSAGE_IGNORE_INSERTS = 0x00000200 local LANG_NEUTRAL = 0x00 local SUBLANG_DEFAULT = 0x01 local function MAKELANGID(p, s) return s * 2^10 + p end -- C function declarations local FormatMessage = assert(kernel32.FormatMessageA) FormatMessage:types{ret ='int', abi = 'stdcall', 'int', 'pointer', 'int', 'int', 'pointer', 'int', 'pointer'} local GetLastError = assert(kernel32.GetLastError) GetLastError:types{ret = 'int', abi = 'stdcall'} local LocalFree = assert(kernel32.LocalFree) LocalFree:types{ret = 'pointer', abi = 'stdcall', 'pointer'} local buf = alien.buffer(4) buf:set(0, buf2, 'pointer') local ret = FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER + FORMAT_MESSAGE_FROM_SYSTEM + FORMAT_MESSAGE_IGNORE_INSERTS, nil, GetLastError(), MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), buf, -- ref: msg_buf, 0, nil ) if ret == 0 then return "Unknown error." end local msg = alien.tostring(buf:get(1,'pointer')) LocalFree(buf:get(1, 'pointer')) return msg end local function config(h, t) local speed = t.speed local databits = t.databits local stopbits = t.stopbits local parity = t.parity local handshake = t.handshake assert(stopbits_to_win32[stopbits]) assert(parity_to_win32[parity]) assert(databits == 5 or databits == 6 or databits == 7 or databits == 8) assert(type(speed) == 'number' and speed > 0) -- C function declarations local GetCommState = kernel32.GetCommState GetCommState:types{ret = "int", abi = 'stdcall', "pointer", "pointer"} local SetCommState = assert(kernel32.SetCommState) SetCommState:types{ret = "int", abi = 'stdcall', "pointer", "pointer"} local SetCommTimeouts = assert(kernel32.SetCommTimeouts) SetCommTimeouts:types{ret = "int", abi = 'stdcall', "pointer", "pointer"} local buf = alien.buffer(4*3 + 3*2 + 3*1 + 5*3 + 2*1) GetCommState(h, buf) local offset_DCBlength = 1 local offset_BaudRate = 1 + 1*4 local offset_flags = 1 + 2*4 local offset_XonLim = 1 + 3*4 + 1*2 local offset_XoffLim = 1 + 3*4 + 2*2 local offset_ByteSize = 1 + 3*4 + 3*2 local offset_Parity = 1 + 3*4 + 3*2 + 1 local offset_StopBits = 1 + 3*4 + 3*2 + 2 local offset_XonChar = 1 + 3*4 + 3*2 + 3 local offset_XoffChar = 1 + 3*4 + 3*2 + 4 local offset_ErrorChar = 1 + 3*4 + 3*2 + 5 local offset_EofChar = 1 + 3*4 + 3*2 + 6 local offset_EvtChar = 1 + 3*4 + 3*2 + 7 buf:set(offset_BaudRate, speed, 'int') local bits = buf:get(offset_flags, 'int') bits = changebit(bits, bit(1), true) -- fBinary bits = changebit(bits, bit(2), parity ~= 'none') -- fParity bits = changebit(bits, bit(3), handshake == 'hardware') -- fOutxCtsFlow bits = changebit(bits, bit(4), false) -- fOutxDsrFlow (ok?) bits = changebit(bits, bit(5), false) -- fDtrControl[1] (ok?) bits = changebit(bits, bit(6), false) -- fDtrControl[2] (ok?) bits = changebit(bits, bit(7), false) -- fDsrSensitivity (ok?) bits = changebit(bits, bit(8), false) -- fTXContinueOnXoff (ok?) bits = changebit(bits, bit(9), handshake == 'xon/xoff') -- fOutX bits = changebit(bits, bit(10), handshake == 'xon/xoff') -- fInX bits = changebit(bits, bit(11), false) -- fErrorChar (ok?) bits = changebit(bits, bit(12), false) -- fNull (ok?) bits = changebit(bits, bit(13), false) -- fRtsControl [1] bits = changebit(bits, bit(14), handshake == 'xon/xoff') -- fRtsControl [2] bits = changebit(bits, bit(15), false) -- fAbortOnError (ok?) buf:set(offset_flags, bits, 'int') buf:set(offset_ByteSize, databits, 'byte') buf:set(offset_Parity, parity_to_win32[parity], 'byte') buf:set(offset_StopBits, stopbits_to_win32[stopbits], 'byte') SetCommState(h, buf) -- timeout on receive immediately if no data pending -- (so that you have a chance to do bigger an better things) -- http://msdn.microsoft.com/en-us/library/aa363437(VS.85).aspx local buf = alien.buffer(4*5) -- _COMMTIMEOUTS: buf:set(1, -1, "int") -- ReadIntervalTimeout buf:set(1+4*1, 0, "int") -- ReadTotalTimeoutMultiplier buf:set(1+4*2, 0, "int") -- ReadTotalTimeoutConstant buf:set(1+4*3, 0, "int") -- WriteTotalTimeoutMultiplier buf:set(1+4*4, 0, "int") -- WriteTotalTimeoutConstant SetCommTimeouts(h, buf) end local CloseHandle local function open(t) local port = t.port assert(type(port) == 'string' and port:match('^COM[0-9]+$'), 'invalid port name '..port..'; expecting e.g. "COM1"') local portNum = port:match("^COM([0-9]+)") if portNum+0 >= 10 then port = "\\\\.\\"..port end -- C function declarations local CreateFile = assert(kernel32.CreateFileA) CreateFile:types{ret = "pointer", abi = 'stdcall', "string", "int", "int", "pointer", "int", "int", "pointer"} CloseHandle = assert(kernel32.CloseHandle) CloseHandle:types{ret = 'int', abi = 'stdcall', "pointer"} local n = (GENERIC_READ + GENERIC_WRITE) - 2^32 + 1 local h = CreateFile(port, n, 0, nil, OPEN_EXISTING, 0, nil) -- convert handle to int local tmp = alien.buffer(4) tmp:set(1, h, 'pointer') local hnum = tmp:get(1, 'int') if hnum == -1 then return nil, get_last_error() end local ok, msg = pcall(config, h, t) if not ok then CloseHandle(h) return nil, msg end return h end M.open = open local function close(h) CloseHandle(h) end M.close = close local function send(h, s) local WriteFile = assert(kernel32.WriteFile) WriteFile:types{ret="int", abi = 'stdcall', "pointer", "string", "int", "ref int", "pointer"} local bytes_written_buf = alien.buffer(4) local ret, nwritten = WriteFile(h, s, #s, 0, nil ) if ret == 0 or nwritten ~= #s then error("failed write: " .. get_last_error()) end end M.send = send local function receive(h) -- C function declarations local ReadFile = assert(kernel32.ReadFile) ReadFile:types{ ret = 'int', abi = 'stdcall', "pointer", "ref char", "int", "ref int", "pointer"} local ret, char, nread = ReadFile(h, buffer_buf, 1, 0, nil ) if ret == 0 then error("failed read: " .. get_last_error()) end if char < 0 then char = char+256 end -- avoid negatives return nread == 1 and string.char(char) or nil end M.receive = receive local function receive_all(h) local s = "" while 1 do local c = receive(h) if c then s = s .. c else return s end end end M.receive_all = receive_all local buf = "" local function async_read_until(h, char) while 1 do local c = receive(h) if c then buf = buf .. c if c == char then local s = buf buf = "" return s end else return end end end local function SetDTR(h, set) local EscapeCommFunction = assert(kernel32.EscapeCommFunction) EscapeCommFunction:types{ret="int", abi = 'stdcall', "pointer", "int"} if set then EscapeCommFunction(h, SETDTR) else EscapeCommFunction(h, CLRDTR) end end M.SetDTR = SetDTR local function SetRTS(h, set) local EscapeCommFunction = assert(kernel32.EscapeCommFunction) EscapeCommFunction:types{ret="int", abi = 'stdcall', "pointer", "int"} if set then EscapeCommFunction(h, SETRTS) else EscapeCommFunction(h, CLRRTS) end end M.SetRTS = SetRTS local function GetCTS(h) local GetCommModemStatus = assert(kernel32.GetCommModemStatus) GetCommModemStatus:types{ret = "int", abi = "stdcall", "pointer", "ref int"} local _, CTS = GetCommModemStatus(h, 0) return CTS == CTS_ON end M.GetCTS = GetCTS local function TransmitChar(h, c) local TransmitCommChar = assert(kernel32.TransmitCommChar) TransmitCommChar:types{ret="int", abi = 'stdcall', "pointer", "int"} if not TransmitCommChar(h, c) then return nil, get_last_error() else return true end end M.TransmitChar = TransmitChar return M
The following is a sample code that redirects all traffic between a serial port and a local socket port. It works for me, but YMMV. Run from Lua command prompt. The outer while loop is to allow repeated reconnects by an ip client without having to restart the script.
local s=require "socket" local com=require "serial" if arg[1] == nil then print("Usage: "..arg[0].." <socket port> ".. "[<com port> [<speed> [<databits> [<parity> [<stopbits>]]]]]") print("Example: "..arg[0].." 10000 COM1 38400 8 none 1") return end local port = tonumber(arg[1]) or 10000 local comport = arg[2] or "COM1" local speed = tonumber(arg[3]) or 38400 local databits = tonumber(arg[4]) or 8 local parity = arg[5] or "none" local stopbits = tonumber(arg[6]) or 1 local sp, errmsg = assert(com.open{port=comport, speed=speed, databits=databits, stopbits=stopbits, parity=parity}) while true do local server = assert(s.bind("127.0.0.1", port )) print("waiting for connection on port", port) local client = assert(server:accept()) print("connected") client:settimeout(0.1) while true do local data, errmsg, partial = client:receive() if errmsg == "closed" then print("connection closed") client:close() server:close() break elseif errmsg == "timeout" then data = partial elseif errmsg then error(errmsg) end if data and data ~= "" then for i = 1, #data do local c = data:sub(i,i) com.send(sp, c) end end data = com.receive_all(sp) if data and data ~= "" then client:send(data) end end end
-- Petr Štetiar <ynezz@true.cz>
