Anp.Serial.Win32 1.0.0

Anp.Serial.Win32

Managed Windows serial (COM port) library for .NET Framework 4.8, .NET Standard 2.0, and .NET 8+. Focused on USB CDC devices and USB-to-serial adapters, with full support for Bluetooth virtual COM ports and physical RS232 ports. All via Win32 P/Invoke.

Devices are identified by their device interface path — the stable, unique symbolic link assigned by the OS — rather than a COM port number. PortName (e.g. COM3) is populated on a best-effort basis from the PnP registry for display and interop with legacy APIs, but the path is the primary identifier used for discovery, open, and hot-plug matching.

Features

• Discovery — enumerate all COM port devices, optionally filtered by USB VID/PID
• Hot-plug monitoring — get notified when devices arrive or are removed (Windows 8+)
• Async I/O — ReadAsync, WriteAsync, ReadExactAsync, ReadToAsync, ReadLineAsync, WriteLineAsync with meaningful per-call timeouts (default 2 s, configurable per operation)
• Graceful disconnect handling — mid-I/O device removal raises SerialDisconnectedException instead of corrupting state; the device transitions cleanly to closed
• Sync wrappers — Write, ReadText, ReadLine, ReadTo for simple use cases
• Serial control — baud rate, data bits, parity, stop bits, DTR/RTS, modem status, purge
• Device metadata — VendorId / ProductId parsed from the device path; FriendlyName and PortName (best-effort, e.g. COM3) read from the PnP registry
• Subclassable — OnOpened() / OnClosing() hooks for protocol initialization and teardown
• Diagnostics — subscribe to SerialDiag.Error for library-level error reporting

Quick Start

A SerialDevice can be created via the built-in discovery or directly from a device interface path obtained from any external source — your own enumeration, a config file, a saved user preference, or a tool like PnpDeviceToolkit.

Discover devices

using Anp.Serial.Win32;

// All COM port devices
var devices = SerialDiscovery.GetDevices();

// Filter by USB VID/PID
var filtered = SerialDiscovery.GetDevices(vendorId: 0x1234, productId: 0x5678);

foreach (var device in devices)
{
    Console.WriteLine($"{device.PortName} — {device.FriendlyName} (VID={device.VendorId}, PID={device.ProductId})");
    device.Dispose();
}

Open, write, read (USB CDC)

USB CDC devices typically don't require PortSettings — the actual line rate is negotiated over the USB control interface, and the default 8N1 configuration works out of the box:

using Anp.Serial.Win32;

// From discovery, config file, or any other source
var device = new SerialDevice(@"\\?\USB#VID_1234&PID_5678#serial#{...}");
device.Open();

// No PortSettings needed for USB CDC — just start talking
await device.WriteLineAsync("HELLO");
string response = await device.ReadLineAsync(timeout: TimeSpan.FromSeconds(5));

device.Close();
device.Dispose();

Open, write, read (USB-to-serial adapter)

For USB-to-serial adapters and physical RS232 ports, configure PortSettings to match the target device:

var device = new SerialDevice(@"\\?\FTDIBUS#VID_0403+PID_6001+...#{...}");
device.Open();

device.PortSettings = new PortSettings
{
    BaudRate = 115200,
    DataBits = 8,
    Parity = Parity.None,
    StopBits = StopBits.One
};

await device.WriteLineAsync("HELLO");
string response = await device.ReadLineAsync(timeout: TimeSpan.FromSeconds(5));

device.Close();
device.Dispose();

Monitor hot-plug events

using Anp.Serial.Win32;

using (var watcher = new SerialWatcher(vendorId: 0x1234))
{
    watcher.DeviceArrived += (s, e) => Console.WriteLine($"Connected: {e.DevicePath}");
    watcher.DeviceRemoved += (s, e) => Console.WriteLine($"Disconnected: {e.DevicePath}");
    watcher.StartWatching();

    Console.ReadLine(); // keep alive
}

Subclass for protocol initialization

public class MyDevice : SerialDevice
{
    public MyDevice(string path) : base(path) { }

    protected override void OnOpened()
    {
        // Device is open — send handshake, configure settings, etc.
        PortSettings = new PortSettings { BaudRate = 9600, DataBits = 8 };
        WriteLineAsync("INIT").GetAwaiter().GetResult();
    }

    protected override void OnClosing()
    {
        // Device is about to close — send goodbye, flush, etc.
        WriteLineAsync("BYE").GetAwaiter().GetResult();
    }
}

// Use with discovery
var devices = SerialDiscovery.GetDevices<MyDevice>(path => new MyDevice(path));

API Overview

SerialDevice

All async methods accept an optional TimeSpan? timeout parameter (default: 2 seconds).

SerialDiscovery

SerialWatcher

Diagnostics

SerialDiag.Error += (sender, error) =>
{
    Console.WriteLine($"[{error.Member}] {error.Message} {error.Exception}");
};

Requirements

• .NET Framework 4.8, .NET Standard 2.0, or .NET 8+ (Windows)
• Windows Vista or later (discovery and I/O)
• Windows 8 or later (SerialWatcher hot-plug monitoring)

License

See LICENSE in the repository root.

Links

• GitHub
• NuGet