Manual OBDII query

manual_OBDII.lua

--Implements a simple OBDII engine in lua scripting, with a configurable delay between PIDs. 
-- IMPORTANT: Ensure built-in OBDII is turned off in Setup
--
--500K baud. set your baud rate here.
initCAN(0, 500000) 
--standard 11 bit PID request  0x7DF
--extended 29 bit PID request  0x18DB33F1

--standard 11 bit PID response 0x7E8
--extended 29 bit PID response 0x18DAF110
standard = true

--delay between PID queries, in mS
delay = 1000

--this function checks the PID response
function checkPidResponse()
  local pid = nil
  local id
  local ext
  local data
  id, ext, data = rxCAN(0, 1000)

  if ext == 1 and id == 0x18DAF110 then
    pid = data[3]   
  end

  if ext == 0 and id == 0x7E8 then
    pid = data[3]
  end

  if pid ~= nil then
    local mapper = mappers[pid]
    if mapper ~= nil then
      local value = mapper(data)
      local chId = pids[pid]
      setChannel(chId, value)
      return true    
    end
  end
end

function request_pid(pid)
  local r

  if standard then
    r = txCAN(0, 0x7DF,0 , {2, 1, pid})
  else
    r = txCAN(0, 0x18DB33F1,1 , {2, 1, pid})
  end

--  println('request pid ' ..pid ..' result ' ..r)
end

function onTick()
  sleep(delay)
  request_pid(query[queryIndex])
  checkPidResponse()
  queryIndex = queryIndex + 1
  if queryIndex > queryLen then queryIndex = 1 end
end

function rpmMapper(data)
  a = data[4]
  b = data[5]
  return (a * 256 + b) / 4
end

function tpsMapper(data)
  return data[4] / 2.55
end

function tempMapper(data)
  local degC = data[4] - 40
  local degF = degC * 1.8 + 32
  return degF
  --return degC
end

rpmId = addChannel("RPM", 25, 0, 0, 10000)
tpsId = addChannel("TPS", 25, 0, 0, 100)
tempId = addChannel("EngineTemp", 1, 0, 0, 300)

setTickRate(50)  
pids = {}
pids[12] = rpmId
pids[17] = tpsId
pids[5] = tempId

query = {12,17, 12,17, 12,17, 12,17, 12,17, 5}
queryLen = #query
queryIndex = 1

mappers = {}
mappers[12] = rpmMapper
mappers[17] = tpsMapper
mappers[5] = tempMapper