reading sensor data from air master 2 air quality monitor

airMaster2.fsx

#r "nuget: FSharp.Charting, 2.1.0"
#r "nuget: System.Windows.Forms, 4.0.0"
#r "System.Windows.Forms.DataVisualization"
#r "nuget: FSharp.Control.Reactive, 5.0.2"

open System
open FSharp.Control.Reactive
open FSharp.Charting
open System.IO.Ports


type Sensors = { 
    time: int64;
    pm25: double; 
    pm10: double; 
    hcho: double; 
    tvoc: double; 
    co2: double; 
    temp: double; 
    humidity: double; 
    }

let event1 = new Event<Sensors>()

let port = new SerialPort("COM3", 19200, Parity.None, 8, StopBits.One);
port.Open()
let read (buff:byte[]) pos = double(buff.[pos]) * 255.0 + double(buff.[pos+1])

let hexCodes = "55 CD 47 00 00 00 00 00 00 01 69 0D 0A".Split(' ') |> Seq.ofArray
let reqArr = hexCodes|>Seq.map(fun x-> Byte.Parse(x, System.Globalization.NumberStyles.HexNumber))|> Seq.toArray

let sendReq () = 
    printfn "Sending req"
    port.Write(reqArr, 0, reqArr.Length) |> ignore
let timer = new System.Timers.Timer(5000.0)
timer.Elapsed.Add (fun _ -> sendReq() )
//timer.AutoReset = false
timer.Start()

let buff : byte[] = Array.zeroCreate 40

let rec readPort pos = 
    let expectedCount =  buff.Length - pos
    let count = port.Read(buff, pos, expectedCount)
    //printfn "Recieved expected %d real %d" expectedCount count
    if count = expectedCount then ()
    else readPort (pos + count)


let port_DataReceived (sender : obj) (e : SerialDataReceivedEventArgs) = 
    readPort 0
    printfn "Recieved packet"  
    let status = {
         time = DateTimeOffset.UtcNow.ToUnixTimeSeconds();
         pm25 = read buff 1;
         pm10 = read buff 3;
         hcho = (read buff 5) / 1000.0;
         tvoc = (read buff 7) /1000.0;
         co2 = (read buff 9);
         temp = (read buff 11) / 100.0;
         humidity = (read buff 13) / 100.0;
    }
    event1.Trigger(status)
    //timer.Start()
    

port.DataReceived.AddHandler <| new SerialDataReceivedEventHandler(port_DataReceived);

let ev = event1.Publish |> Observable.map (fun x-> x)
ev.Subscribe(fun x-> printfn "status %A" x)

let c = LiveChart.FastLineIncremental(ev |> Observable.map (fun x-> (x.time, x.co2)), Name="co2").WithXAxis(Enabled=true).WithYAxis(Enabled=true, Min = 400.0, Max = 1100.0)
c.ShowChart()
let c2 = LiveChart.FastLineIncremental(ev|> Observable.map (fun x-> (x.time, x.humidity)),Name="humidity").WithXAxis(Enabled=true).WithYAxis(Enabled=true)
c2.ShowChart()