Problem with opening portby script in Pixhawk cube orange

I made an electronic circuit what measures several parameters of combustion motor and generate standard MAVLink2 frame EFI_STATUS with measured data. I wanted to display those data in “Quick” panel of Mission Planner. On this forum I get suggestion to write LUA script to decode MAVLink2 data. I did it and finally have script what decodes data and creates variables what can be displayed in Quick, but stil have 2 problems:

  1. On empty Pixhawk it works OK, but on other device with some other configuration I get message: “insufficient memory loading APM/scripts/Manager_Silnika.lua”. On my empty pixhawk with running script I have Status → fremem = 497000. When delete script have Status → freemem = 497736. It looks the script use 736 bytes. On pixhawk with “oher configuration” I can read Status → freemem = 528216. It is even more, but script do not run. Don’t understand why?

  2. I can connect my device to TELEM1, TELEM2 or GPS2 port. In Mission Planner I configure port protocol to “Scripting”. In my script I create variable “port” and assign to it handler(?) to one of the ports for example:
    local port = serial:find_serial(1)
    I had problem with opening port, but finally discover when few other ports is configured to “scripting” protocol, it works. It is OK for empty device, but when other devices are connected to other ports it become a problem. I get information the port what I can use is GPS2 so tried several configuration to find configuration what will work. Finally found 2 configurations, but one require “scripting” has to be set on TELEM2, Serial3 and Serial4. Other working configuration is as above + Serial5. Below is table with most of possible configurations for GPS2 port. In script I open serial_port 2

    I can get 3 kind of behaviors described in legend. Port can’t be opened, can be opened but script don’t work, or all works OK (green colour)

To understand it I did some more work. In script I was able to open port with numbers 0, 1 and 2 (probably TELEM1, TELEM2 and GPS). Just did test with opening port 1 when device is connected to one of 3 possible ports and try to open all 3 ports with script by simple plugging plug into another socket and reset pixhawk. Results are below:

Completely don’t understand this logic. It must be a bug but where? In my script or somewhere other?
Include my script:

Skrypt LUA dekodujący ramkę MAVLink2 przychodzącą z managera silnika.
Zdekodowane dane są deklarowane w Mission Planner jako zmienne użytkownika i są wyswietlane 
z przedrostkiem MAV_ w oknie gdzie wybiera się źródło danych dla panelu Quick
w Quick trzeba kliklnąć w jedną z liczb, wtedy otwiera się powyższe okno z naszymi danymi.

Wybieramy wolny port UART w pixhawku np. Telem2
1) CONFIG -> Standard Param -> Telemetry 2 Baud Rate = 57600
2) CONFIG -> Standard Param -> Telemetry 2 protocol selection = Scripting (28)

(c) Piotr Laskowski 
Opracowano na bazie kodu napisanego przez Stephen Dade (  !Uwaga - numery portów są blędne
Serial 0    USB port
Serial 1    Telemetry port 1
Serial 2    Telemetry port 2
Serial 3    GPS1 port
Serial 4    GPS2 port
Serial 5    USER port
Serial 6    USER port
Serial 7    USER port

gcs:send_text(0, "Start MAVLink LUA script")
--local port = serial:find_serial(0)  -- 0=Telem1
local port = serial:find_serial(1)  -- 1=Telem2
--local port = serial:find_serial(2)  -- 2=GPS2 
--local port = serial:find_serial(3)  -- 3=GPS1 (sprawdzić)

if not port == 0 then
    gcs:send_text(0, "No Scriping Serial Port: "  .. tostring(port))


local function MAVLinkProcessor()
    -- public fields
    local self = {
        -- define MAVLink message id's
        EFI_STATUS  = 225

    -- private fields
    local _mavbuffer = ""     -- bufer for incoming data
    local _mavresult = {}     -- buffer for parts of frame body  
    local _payload_len = 0
    local _mavdecodestate = 0 -- 0=looking for marker, 1=getting header,2=getting payload,3=getting crc
    HEADER_LEN_V2 = 10
    EFI_FRAME_LEN = 73
    --local _txseqid = 0

    -- AUTOGEN from MAVLink generator
    local _crc_extra = {}
    _crc_extra[75] = 0x9e
    _crc_extra[76] = 0x98
    _crc_extra[235] = 0xb3
    _crc_extra[73] = 0x26

    local _messages = {}
    _messages[225] = { -- EFI_STATUS 
        {"ecu_index", "<f"}, {"rpm", "<f"}, {"fuel_consumed", "<f"}, {"fuel_flow", "<f"}, {"engine_load", "<f"}, {"throttle_position", "<f"}, 
        {"spark_dwell_time", "<f"}, {"barometric_pressure", "<f"}, {"intake_manifold_pressure", "<f"}, {"intake_manifold_temperature", "<f"}, 
        {"cylinder_head_temperature", "<f"}, {"ignition_timing", "<f"}, {"injection_time", "<f"}, {"exhaust_gas_temperature", "<f"}, 
        {"throttle_out", "<f"}, {"pt_compensation", "<f"}, {"health", "<B"}, {"ignition_voltage", "<f"}, {"fuel_pressure", "<f"}

    function self.generateCRC(buffer)
        -- generate the x25crc for a given buffer. Make sure to include crc_extra!
        local crc = 0xFFFF
        for i = 1, #buffer do
            local tmp = string.byte(buffer, i, i) ~ (crc & 0xFF)
            tmp = (tmp ~ (tmp << 4)) & 0xFF
            crc = (crc >> 8) ~ (tmp << 8) ~ (tmp << 3) ~ (tmp >> 4)
            crc = crc & 0xFFFF
        return string.pack("<H", crc)

-- parse a new byte and see if we've got MAVLink 2 message
-- returns true if a packet was decoded, false otherwise
    function self.parseMAVLink(byte)        
        _mavbuffer = _mavbuffer .. string.char(byte)
        --gcs:send_text(0, "ds:" .. tostring(_mavdecodestate))

        --gcs:send_text(0, "mbuf size: " .. tostring(#_mavbuffer) .. "ds: " .. tostring(_mavdecodestate))

        -- parse buffer to find MAVLink packets
        --if #_mavbuffer == 1 and string.byte(_mavbuffer, 1) == PROTOCOL_MARKER_V2 and _mavdecodestate == 0 then
        if _mavdecodestate == 0 then
            if #_mavbuffer == 1 and string.byte(_mavbuffer, 1) == PROTOCOL_MARKER_V2 then
                _mavdecodestate = 1
                --gcs:send_text(0, "Header")
                return false
                _mavbuffer = ""

        -- if we have a full header, try parsing
        if #_mavbuffer == HEADER_LEN_V2 and _mavdecodestate == 1 then
            -- wartosc, reszta = string.unpack("format", string, pozycja=1)
            _payload_len, _ = string.unpack("<B", _mavbuffer, 2)            
            _mavresult.seq, _mavresult.sysid, _mavresult.compid, _ = string.unpack("<BBB", _mavbuffer, 5)            
            _mavresult.msgid, _ = string.unpack("I3", _mavbuffer, 8)
            --gcs:send_text(0, "sys:" .. tostring(_mavresult.sysid) ..", comp:" .. tostring(_mavresult.compid) ..", msgid:" .. tostring(_mavresult.msgid) ..", seq:" .. tostring(_mavresult.seq))
            _mavdecodestate = 2
            return false

        -- get payload
        if _mavdecodestate == 2 and #_mavbuffer == (_payload_len + HEADER_LEN_V2) then
            _mavdecodestate = 3
            _mavresult.payload = string.sub(_mavbuffer, HEADER_LEN_V2 + 1)

            --gcs:send_text(0, "pay: " .. tostring(_payload_len) ..", len: " .. tostring(#_mavresult.payload))
            return false

        -- get crc, then process if CRC ok
        if _mavdecodestate == 3 and #_mavbuffer == (_payload_len + HEADER_LEN_V2 + 2) then
            _mavdecodestate = 0
            _mavresult.crc = string.sub(_mavbuffer, -2, -1)

            local message_map = _messages[_mavresult.msgid]
            if not message_map then
                -- we don't know how to decode this message, bail on it
                _mavbuffer = ""
                return true

            -- ignoruj ramki EFI_STATUS  o rozmiarze innym niż domyślny
            if  _mavresult.msgid == 225 and _payload_len ~= EFI_FRAME_LEN then
                _mavbuffer = ""
                gcs:send_text(3, "Wrong frame len")
                return true

            -- check CRC, if message defined
            local crc_extra_msg = _crc_extra[_mavresult.msgid]
            if crc_extra_msg ~= nil then
                local calccrc = self.generateCRC( string.sub(_mavbuffer, 2, -3) .. string.char(crc_extra_msg))
                if _mavresult.crc ~= calccrc then
                    gcs:send_text(3, "Bad CRC: " .. self.bytesToString(_mavbuffer, -2, -1) .. ", " .. self.bytesToString(calccrc, 1, 2))
                    _mavbuffer = ""

            -- map all the fields out
            local offset = 1
            for _, v in ipairs(message_map) do 
                _mavresult[v[1]], offset = string.unpack(v[2], _mavresult.payload, offset)
            _mavbuffer = ""
            gcs:send_text(0, "Decoded")
            gcs:send_named_float("Head1_temp", _mavresult.cylinder_head_temperature)
            gcs:send_named_float("Head2_temp", _mavresult.exhaust_gas_temperature)
            gcs:send_named_float("Local_temp", _mavresult.ignition_timing)

            gcs:send_named_float("Motor_RPM", _mavresult.rpm)
            gcs:send_named_float("Fuel_Lev",  _mavresult.fuel_consumed)
            gcs:send_named_float("Throttle",  _mavresult.throttle_out)
            gcs:send_named_float("Ign_volt",  _mavresult.ignition_voltage)

            --zmienne debugujące
            gcs:send_named_float("Cap_sens1", _mavresult.spark_dwell_time)
            gcs:send_named_float("Cap_sens2", _mavresult.barometric_pressure)
            gcs:send_named_float("Cap_sens3", _mavresult.intake_manifold_pressure)
            gcs:send_named_float("Cap_sens4", _mavresult.intake_manifold_temperature)
            gcs:send_named_float("Test",      _mavresult.fuel_pressure)     
            gcs:send_named_float("Fuel_Min",  _mavresult.engine_load)  
            gcs:send_named_float("Fuel_Max",  _mavresult.throttle_position)  
            return true

        -- packet too big ... start again
        if #_mavbuffer > 263 then 
            _mavbuffer = "" 
            gcs:send_text(0, "To big:" .. tostring(_mavdecodestate))
            _mavdecodestate = 0
        return false

    function self.bytesToString(buf, start, stop)
        local ret = ""
        for idx = start, stop do
            ret = ret .. string.format("0x%x ", buf:byte(idx), 1, -1) .. " "
        return ret


    -- return the instance
    return self

-- Define the MAVLink processor
local mavlink = MAVLinkProcessor()

function HLSatcom()
    -- read in any bytes from UART and and send to MAVLink processor
    -- only read in 1 packet at a time to avoid time overruns
    while port:available() > 0 do
        -- local byte = port:read()
        -- if mavlink.parseMAVLink(byte) then break end

        if mavlink.parseMAVLink(port:read()) then 

    return HLSatcom, 100

return HLSatcom, 100

Increase SCR_HEAP_SIZE on the board that isn’t loading the script.

You are misunderstanding the find_serial() binding. It will only return ports whose protocols are set to scripting, and they are indexed sequentially. So, if you have your serial ports set up like this:


serial:find_serial(0) will return an object referencing SERIAL2.
serial:find_serial(1) will return an object referencing SERIAL4.

Thank you very much. Your help solved both my problems. Now script run on final platform.