Changing serial port configurations programmatically in c#

Question

I have 2 types of devices that have different protocols and are connected with a single serial port. By protocol, I mean that serial port configurations are different.

I have a protocol id p_id by which I can check which device is being currently read. Below is my code

Below is my main function which calls a class named CombinedEngine

 static class Program
 {
   private static CombinedEngine _eng;
   static async Task Main(string[] args)
    {
      try
      {
         _eng = new CombinedEngine();
      }
      catch (Exception ex)
      {
            Debug.WriteLine(ex.Message.ToString());
                //_log.Error(ex, ex.Message);
      }
    }
     while(true);
 }

Combined Engine Class

class CombinedEngine
{
   SerialPort port = new SerialPort();
   public CombinedEngine()
    {          

        try
        {
            
            var p = mdc.mdc_protocol.ToList();
            
            if(p.Count > 0)
            {
                foreach(var pr in p)
                {
                    var p_id = pr.protocol_id;

                    if(p_id=="01")//modbus
                    {
                        if (port.IsOpen)
                            port.Close();

                        port = new SerialPort("COM8", 9600, Parity.Even, 8, StopBits.One);
                        port.ReadTimeout = 500;
                        port.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);                          
                        port.Open();

                        Console.WriteLine("Port opened successfully for modbus...");
                        Console.WriteLine("I am Recieving for modbus...");


                        var result = mdc.mdc_meter_config.Where(m => m.config_flag == 0)
                            .Where(m=>m.p_id == p_id).ToList();

                        if (result.Count > 0)
                        {
                            foreach (var item in result)
                            {
                                var iteration = new Iterations()
                                {
                                    hex = (string)item.m_hex,
                                    row_id = (string)item.row_id,
                                    device_id = (int)item.meter_id,
                                    protocol_id = (string)item.p_id,
                                    command_id = (string)item.command_id,
                                    config_flag = (int)item.config_flag,
                                    msn = (string)item.msn,
                                    time = (string)item.time
                                };
                                confList.Add(iteration);
                                time = Convert.ToDouble(item.time);
                            }

                            var modbus = confList.Where(x => x.protocol_id == "01").ToList();
                            
                            aTimer = new System.Timers.Timer();


                            // Create a timer...
                            aTimer = new System.Timers.Timer();
                            // Hook up the Elapsed event for the timer. 
                            aTimer.Interval = time * 1000.0;
                            aTimer.Elapsed += (sender, e) => MyModbusMethod(sender, e, modbus, aTimer);            
                            aTimer.AutoReset = true;
                            aTimer.Enabled = true;

                        }
                        else
                        {

                            Console.WriteLine("No Data available");
                        }
                    }
                    else if(p_id=="02")//ytl_bus
                    {
                        if (port.IsOpen)
                            port.Close();

                        port = new SerialPort("COM8", 38400, Parity.None, 8, StopBits.One);
                        port.ReadTimeout = 500;
                        port.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);
                        port.Open();

                        Console.WriteLine("Port opened successfully for ytlbus...");
                        Console.WriteLine("I am Recieving for ytlbus...");


                        var result = mdc.mdc_meter_config.Where(m => m.config_flag == 0)
                            .Where(m => m.p_id == p_id).ToList();

                        if (result.Count > 0)
                        {
                            foreach (var item in result)
                            {
                                var iteration = new Iterations()
                                {
                                    hex = (string)item.m_hex,
                                    row_id = (string)item.row_id,
                                    device_id = (int)item.meter_id,
                                    protocol_id = (string)item.p_id,
                                    command_id = (string)item.command_id,
                                    config_flag = (int)item.config_flag,
                                    msn = (string)item.msn,
                                    time = (string)item.time
                                };
                                confList.Add(iteration);
                                time = Convert.ToDouble(item.time);
                            }

                            
                            var ytlbus = confList.Where(x => x.protocol_id == "02").ToList();

                            

                            aTimer = new System.Timers.Timer();


                            // Create a timer...
                            aTimer = new System.Timers.Timer();
                            // Hook up the Elapsed event for the timer. 
                            aTimer.Interval = time * 1000.0;
                            aTimer.Elapsed += (sender, e) => MyElapsedMethod(sender, e,ytlbus , aTimer);            
                            aTimer.AutoReset = true;
                            aTimer.Enabled = true;

                        }
                        else
                        {

                            Console.WriteLine("No Data available");
                        }

                    }

                   
                    
                   
                }
               
            }
           

        }
        catch (Exception ex)
        {
            Console.WriteLine("Error at Line " + LineNumber(), ex.Message.ToString());
            throw ex;
        }
       
       
    }


}

In the above code, I have checked that if p_id is equal to 01 then modbus serial port configurations should be done. But if p_id is 02 then ytlbus serial port configurations should be encountered. Both devices have a different baud rate and a parity bit. So I have tried to set them

Also, I have a timer which is 60 seconds. So after every 60 seconds, the next timer will be initialized.

For example. If p_id is 01 the code sets the baud rate to 9600 and parity to Even. Then SerialDataRecievedEventHandler is called which will check for any incoming data from the devices and it will manage the data dumping into the DB.

Then the code will check the device details from a table mdc_meter_config and take out relevant information from it. All the details are added to the list one by one for all the devices. Also, the time would be carried out. In this case, all device's time is the same i.e. 60 seconds.

The list is then passed to a variable which is then passed to an ElapsedEventHandler function. The frame sending is handled by it.

The same will be done for p_id equals 02 the only difference is that it will set the baud rate to 38400 and parity to None.

What problem I am facing?

The above code runs, the issue that I am facing is that both conditions worked at the same time. i.e. for 01, it will work and then simultaneously it will jump to the 02 condition. Below is the image

It should complete the work for any p_id value, then complete the work for other p_id value.

Update 1

I have updated my code. Added a new async function, added only a single timer. and added a class for serial port extentions

    public static class SerialPortExtensions
{
    public async static Task ReadAsync(this SerialPort serialPort, byte[] buffer, int offset, int count)
    {
        var bytesToRead = count;
        var temp = new byte[count];

        while (bytesToRead > 0)
        {
            var readBytes = await serialPort.BaseStream.ReadAsync(temp, 0, bytesToRead);
            Array.Copy(temp, 0, buffer, offset + count - bytesToRead, readBytes);
            bytesToRead -= readBytes;
        }
    }

    public async static Task<byte[]> ReadAsync(this SerialPort serialPort, int count)
    {
        var buffer = new byte[count];
        await serialPort.ReadAsync(buffer, 0, count);
        return buffer;
    }
}

public CombinedEngine()
    {
        try
        {
            var p = mdc.mdc_protocol.ToList();

            if (p.Count > 0)
            {
                foreach (var pr in p)
                {
                    var p_id = pr.protocol_id;

                    if (p_id == "01")//modbus
                    {
                        if (port.IsOpen)
                            port.Close();
                        comm = true;
                        port = new SerialPort("COM8", 9600, Parity.Even, 8, StopBits.One);
                        port.ReadTimeout = 500;
                        //port.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);
                        port.Open();
                        Work();

                        Console.WriteLine("Port opened successfully for modbus...");
                        Console.WriteLine("I am Recieving for modbus...");
                        
                    }
                    else if (p_id == "02")//ytl_bus
                    {
                        if (port.IsOpen)
                            port.Close();
                        comm = true;
                        port = new SerialPort("COM8", 38400, Parity.None, 8, StopBits.One);
                        port.ReadTimeout = 500;
                        //port.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);
                        port.Open();
                        Work();

                        Console.WriteLine("Port opened successfully for ytlbus...");
                        Console.WriteLine("I am Recieving for ytlbus...");                          

                    }
                    var result = mdc.mdc_meter_config.Where(m => m.config_flag == 0).ToList();
                    if (result.Count > 0)
                    {
                        foreach (var item in result)
                        {
                            var iteration = new Iterations()
                            {
                                hex = (string)item.m_hex,
                                row_id = (string)item.row_id,
                                device_id = (int)item.meter_id,
                                protocol_id = (string)item.p_id,
                                command_id = (string)item.command_id,
                                config_flag = (int)item.config_flag,
                                msn = (string)item.msn,
                                time = (string)item.time
                            };
                            confList.Add(iteration);
                            time = Convert.ToDouble(item.time);
                        }

                        var modbus = confList.Where(x => x.protocol_id == "01").ToList();
                        var ytlbus = confList.Where(x => x.protocol_id == "02").ToList();

                        //ModbusMethod(modbus);

                        aTimer = new System.Timers.Timer();
                        // Create a timer...
                        aTimer = new System.Timers.Timer();
                        // Hook up the Elapsed event for the timer. 
                        aTimer.Interval = time * 1000.0;
                        aTimer.Elapsed += (sender, e) => MyElapsedMethod(sender, e, ytlbus, modbus, aTimer);
                        //aTimer.Elapsed += OnTimedEvent(iterations, dataItems);            
                        aTimer.AutoReset = true;
                        aTimer.Enabled = true;

                    }
                    else
                    {

                        //Console.WriteLine("No Data available");
                    }

                }

            }


        }
        catch (Exception ex)
        {
            Console.WriteLine("Error at Line " + LineNumber(), ex.Message.ToString());
            throw ex;
        }
        finally
        {
        }


    }

public async void Work()
    {
        try
        {
            var data = await port.ReadAsync(4096);
            Console.WriteLine("Data at Line " + LineNumber(), data.ToString());
            //DoStuff(data);
        }
        catch (Exception ex)
        {
            Console.WriteLine("Error at Line " + LineNumber(), ex.Message.ToString());
        }
    }

The error now I am getting is The I/O operation has been aborted because of either a thread exit or an application request.

at System.IO.Ports.InternalResources.WinIOError(Int32 errorCode, String str) at System.IO.Ports.SerialStream.EndRead(IAsyncResult asyncResult) at System.IO.Stream.<>c.b__43_1(Stream stream, IAsyncResult asyncResult) at System.Threading.Tasks.TaskFactory1.FromAsyncTrimPromise1.Complete(TInstance thisRef, Func3 endMethod, IAsyncResult asyncResult, Boolean requiresSynchronization) at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter1.GetResult() at CommunicationProfile.SerialPortExtensions.d__0.MoveNext() in F:\MDC Development\Scheduler\CommunicationProfile\CombinedEngine.cs:line 1198 at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter.GetResult() at CommunicationProfile.SerialPortExtensions.d__1.MoveNext() in F:\MDC Development\Scheduler\CommunicationProfile\CombinedEngine.cs:line 1207 at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() at CommunicationProfile.CombinedEngine.d__27.MoveNext() in F:\MDC Development\Scheduler\CommunicationProfile\CombinedEngine.cs:line 368

The error is occurring at below lines

var readBytes = await serialPort.BaseStream.ReadAsync(temp, 0, bytesToRead);//1198 line
await serialPort.ReadAsync(buffer, 0, count);//1207 line 
var data = await port.ReadAsync(4096); // 368 line

Note: The above method should be running continuously as the devices are powered on and will send their data after every 60 seconds.

Any help would be highly appreciated.

Answer 1

The main problem with the last revision of your code is that you are calling Work() without await, so the call just creates an asynchronous background task and doesn't wait for its completion. Also, this functionality should not exist inside the constructor, but in a separate async method.

Second suggestion is to remove the if/switch statements from the loop, and place the data needed to differentiate these protocols in a separate class. You could place any additional properties needed for each protocol inside this class:

// contains specific settings for each ProtocolId
class ProtocolCfg
{
    public string ProtocolId { get; set; }
    public string PortName { get; set; }
    public int BaudRate { get; set; }
    public Parity Parity { get; set; }
    public int DataBits { get; set; }
    public StopBits StopBits { get; set; }

    public ProtocolCfg(string id, string port, int baud, Parity parity, int bits, StopBits stop)
    {
        ProtocolId = id; PortName = port; BaudRate = baud; Parity = parity;
        DataBits = bits; StopBits = stop;
    }
}

With this in place, your for loop doesn't need to differentiate between these protocols:

class CombinedEngine
{
    readonly ProtocolCfg[] _portConfigs;

    public CombinedEngine(ProtocolCfg[] portConfigs)
    {
        // just assign the field and do nothing else
        _portConfigs = portConfigs;
    }

    public async Task Run(CancellationToken cancelToken)
    {
        // repeat indefinitely
        while (!cancelToken.IsCancellationRequested)
        {
            // run all protocols
            foreach (var portcfg in _portConfigs)
            {
                SerialPort serialPort = null;

                try
                {
                    // init using current config
                    serialPort = new SerialPort(
                         portcfg.PortName, portcfg.BaudRate, portcfg.Parity,
                         portcfg.DataBits, portcfg.StopBits);

                    serialPort.ReadTimeout = 500;

                    // await data
                    var data = await serialPort.ReadAsync(4096);

                    // do something with this data
                    Console.WriteLine($"P{portcfg.ProtocolId}: {data.Length}B received");

                    // do other stuff here

                    // wait between protocol changes if needed?
                    await Task.Delay(500, cancelToken);
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.ToString());
                }
                finally
                {
                    serialPort?.Close();
                    serialPort?.Dispose();
                }
            }

            // wait between iterations?
            await Task.Delay(500, cancelToken);
        }
    }
}

When calling the Run function, remember that it's async, so you need to call await. However, you also may want to wait for a keypress inside the console, so in that case you would store the returned Task in a variable, and cancel it when needed:

class Program
{
    static void Main(string[] args)
    {
        // define all possible protocols
        var protocols = new[]
        {
            new ProtocolCfg("01", "COM8",  9600, Parity.Even, 8, StopBits.One),
            new ProtocolCfg("02", "COM8", 38400, Parity.None, 8, StopBits.One)
        };

        // we will need this to tell the async task to end
        var tokenSource = new CancellationTokenSource();
        var token = tokenSource.Token; 

        // note that this constructor does not do anything of importance
        var engine = new CombinedEngine(protocols);

        // this is where all the work is done, pass the cancellation token 
        var task = engine.Run(token);

        // wait until Q is pressed
        Console.WriteLine("Running, press Q to quit... ");
        ConsoleKey k;
        do { k = Console.ReadKey().Key; }
        while (k != ConsoleKey.Q);

        // shutdown
        tokenSource.Cancel();
        task.Wait();            
        Console.WriteLine("Done.");
    }        
}