C# 检查 COM（串行）端口是否已打开
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C# check if a COM (Serial) port is already open
提问by TK.
Is there an easy way of programmatically checking if a serial COM port is already open/being used?
是否有一种简单的方法可以以编程方式检查串行 COM 端口是否已打开/正在使用？
Normally I would use:
通常我会使用：
try
{
// open port
}
catch (Exception ex)
{
// handle the exception
}
However, I would like to programatically check so I can attempt to use another COM port or some such.
但是，我想以编程方式进行检查，以便我可以尝试使用另一个 COM 端口或类似端口。
采纳答案by Fionn
I needed something similar some time ago, to search for a device.
前段时间我需要类似的东西来搜索设备。
I obtained a list of available COM ports and then simply iterated over them, if it didn't throw an exception i tried to communicate with the device. A bit rough but working.
我获得了一个可用 COM 端口的列表，然后简单地遍历它们，如果它没有抛出异常，我尝试与设备进行通信。有点粗糙但工作。
var portNames = SerialPort.GetPortNames();
foreach(var port in portNames) {
//Try for every portName and break on the first working
}
回答by gimel
The SerialPort classhas an Openmethod, which will throw a few exceptions. The reference above contains detailed examples.
该SerialPort类有一个开放式的方法，这将引发一些例外。上面的参考资料包含详细的例子。
See also, the IsOpenproperty.
另请参阅IsOpen属性。
A simple test:
一个简单的测试：
using System;
using System.IO.Ports;
using System.Collections.Generic;
using System.Text;
namespace SerPort1
{
class Program
{
static private SerialPort MyPort;
static void Main(string[] args)
{
MyPort = new SerialPort("COM1");
OpenMyPort();
Console.WriteLine("BaudRate {0}", MyPort.BaudRate);
OpenMyPort();
MyPort.Close();
Console.ReadLine();
}
private static void OpenMyPort()
{
try
{
MyPort.Open();
}
catch (Exception ex)
{
Console.WriteLine("Error opening my port: {0}", ex.Message);
}
}
}
}
回答by Funky81
You can try folloing code to check whether a port already open or not. I'm assumming you dont know specificaly which port you want to check.
您可以尝试以下代码来检查端口是否已经打开。我假设您不知道要检查哪个端口。
foreach (var portName in Serial.GetPortNames()
{
SerialPort port = new SerialPort(portName);
if (port.IsOpen){
/** do something **/
}
else {
/** do something **/
}
}
回答by Jeff
This is how I did it:
我是这样做的：
[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
internal static extern SafeFileHandle CreateFile(string lpFileName, int dwDesiredAccess, int dwShareMode, IntPtr securityAttrs, int dwCreationDisposition, int dwFlagsAndAttributes, IntPtr hTemplateFile);
then later on
然后后来
int dwFlagsAndAttributes = 0x40000000;
var portName = "COM5";
var isValid = SerialPort.GetPortNames().Any(x => string.Compare(x, portName, true) == 0);
if (!isValid)
throw new System.IO.IOException(string.Format("{0} port was not found", portName));
//Borrowed from Microsoft's Serial Port Open Method :)
SafeFileHandle hFile = CreateFile(@"\.\" + portName, -1073741824, 0, IntPtr.Zero, 3, dwFlagsAndAttributes, IntPtr.Zero);
if (hFile.IsInvalid)
throw new System.IO.IOException(string.Format("{0} port is already open", portName));
hFile.Close();
using (var serialPort = new SerialPort(portName, 115200, Parity.None, 8, StopBits.One))
{
serialPort.Open();
}
回答by Switch
Sharing what worked for me (a simple helper method):
分享对我有用的东西（一个简单的辅助方法）：
private string portName { get; set; } = string.Empty;
/// <summary>
/// Returns SerialPort Port State (Open / Closed)
/// </summary>
/// <returns></returns>
internal bool HasOpenPort()
{
bool portState = false;
if (portName != string.Empty)
{
using (SerialPort serialPort = new SerialPort(portName))
{
foreach (var itm in SerialPort.GetPortNames())
{
if (itm.Contains(serialPort.PortName))
{
if (serialPort.IsOpen) { portState = true; }
else { portState = false; }
}
}
}
}
else { System.Windows.Forms.MessageBox.Show("Error: No Port Specified."); }
return portState;
}
Notes:
- For more advanced technique(s) I recommend using ManagementObjectSearcher Class.
More info Here.
- For Arduino devices I would leave the Port Open.
- Recommend using a Try Catch block if you need to catch exceptions.
- Check also: "TimeoutException"
- More information on how to get SerialPort (Open) Exceptions Here.
注意：
- 对于更高级的技术，我建议使用ManagementObjectSearcher Class。
更多信息在这里。
- 对于 Arduino 设备，我会让端口保持打开状态。
- 如果您需要捕获异常，建议使用 Try Catch 块。
- 还要检查：“TimeoutException”
- 有关如何在此处获取 SerialPort (Open) Exceptions 的更多信息。
回答by Farrukh Azad
public void MobileMessages(string ComNo, string MobileMessage, string MobileNo)
{
if (SerialPort.IsOpen )
SerialPort.Close();
try
{
SerialPort.PortName = ComNo;
SerialPort.BaudRate = 9600;
SerialPort.Parity = Parity.None;
SerialPort.StopBits = StopBits.One;
SerialPort.DataBits = 8;
SerialPort.Handshake = Handshake.RequestToSend;
SerialPort.DtrEnable = true;
SerialPort.RtsEnable = true;
SerialPort.NewLine = Constants.vbCrLf;
string message;
message = MobileMessage;
SerialPort.Open();
if (SerialPort.IsOpen )
{
SerialPort.Write("AT" + Constants.vbCrLf);
SerialPort.Write("AT+CMGF=1" + Constants.vbCrLf);
SerialPort.Write("AT+CMGS=" + Strings.Chr(34) + MobileNo + Strings.Chr(34) + Constants.vbCrLf);
SerialPort.Write(message + Strings.Chr(26));
}
else
("Port not available");
SerialPort.Close();
System.Threading.Thread.Sleep(5000);
}
catch (Exception ex)
{
message.show("The port " + ComNo + " does not exist, change port no ");
}
}
