System.IO.Ports.ReadByte()

[severa-astrosysteme]

Description

Hello, I have really big performance issues for method ReadByte() - the performance is more than 10 times slower.

The problem were tested and confirmed from my side on
NET7/8/9
Last stable version is NET6

I tried to use serialPort.Read instead, but when I converted it to chars the recieved chars are different (last part in video)

2025-03-25_19h39_15.mp4

NET6 example

NET9 example

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[elgonzo]

SerialPort.Read reads bytes, not chars. While i don't know nothing about your code, i still assume that the unexpected characters you got is due to your code doing byte array to string conversion incorrectly in some way (like for example not using the correct text encoding/code page perhaps...)

Also, regarding the alleged 10x slower performance of SerialPort.ReadByte, any code example to share that exhibits such a "slowness" of this order of magnitude? It might very well be a case that a substantial part of that "slowness" isn't being the SerialPort.ReadByte API itself but caused by your code using SerialPort.ReadByte and processing bytes one at a time. Without knowing the code in question, it's hard to tell...

[severa-astrosysteme]

using System;
using System.IO.Ports;

namespace Demo
{
class Program
{
public static SerialPort serialPort;
static void Main(string[] args)
{
string portName = "COM1"; // Change according to your port
int baudRate = 19200; // Set the appropriate baud rate

        serialPort = new SerialPort(portName, baudRate);

        try
        {
            serialPort.DataReceived += SerialPort_DataReceived;
            serialPort.Open();

            Console.WriteLine($"Serial port {portName} opened. Waiting for data...");
            Console.ReadLine(); // Waits for user input to prevent the program from ending immediately
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error: {ex.Message}");
        }
        finally
        {
            if (serialPort.IsOpen)
            {
                serialPort.Close();
                Console.WriteLine("Serial port closed.");
            }
        }
    }

    public static void ReadDemo()
    {
        int receivedInt = serialPort.ReadByte();

        Console.WriteLine($"{DateTime.Now}:{(char)receivedInt}");
    }
    private static void SerialPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
    {
        ReadDemo();
    }

}

}

[severa-astrosysteme]

SerialPort.Read reads bytes, not chars. While i don't know nothing about your code, i still assume that the unexpected characters you got is due to your code doing byte array to string conversion incorrectly in some way (like for example not using the correct text encoding/code page perhaps...)

Also, regarding the alleged 10x slower performance of SerialPort.ReadByte, any code example to share that exhibits such a "slowness" of this order of magnitude? It might very well be a case that a substantial part of that "slowness" isn't being the SerialPort.ReadByte API itself but caused by your code using SerialPort.ReadByte and processing bytes one at a time. Without knowing the code in question, it's hard to tell...

I placed some simple code so if I run it in NET6 - with System.IO.Ports 6.0.0 and then in NET9 - with 9.0.3
code is compleatly same

2025-03-26_11h33_58.mp4