I am trying to send an SMS from computer to cell phone.
The first step: get all com ports to use it.
I used this code, but no benefit:
private void Form1_Load(object sender, EventArgs e)
{
string[] Ports = SerialPort.GetPortNames();
foreach (string prt in Ports)
{
comboBox1.Items.Add(prt);
}
}
It returns nothing. What can I do?
I just ran the following code on my PC and it returns "COM1":
string[] ports = SerialPort.GetPortNames();
Console.WriteLine("The following serial ports were found:");
foreach(string port in ports)
{
Console.WriteLine(port);
}
Console.ReadLine();
So, it's either permissions or you don't have any Serial ports. Or perhaps your registry is corrupt?
Note:
The port names are obtained from the system registry (for example,
HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\SERIALCOMM). If the registry
contains stale or otherwise incorrect data then the GetPortNames
method will return incorrect data.
Ref: SerialPort.GetPortNames
I had the same issue at first. Then realized that I didn't connect any device to my PC which identify themselves as a serial port (either via USB or any other physical port). It displayed accurately when I connected a device (a USB based PIC programmer in my case). Please check if your device is properly detected.
Related
I am writing an application that will loop through my computer's com ports. The issue I am having is one of the com ports is opened on PC startup by another process which causes an exception to be thrown:
System.InvalidOperationException: 'The port is already open.'
I have successfully handled the exception but it seems to break the foreach loop once it hits the exception and will not continue to the other ports. Am I handling the expectation correctly by having the try catch block inside of the foreach loop?
private void Rescan()
{
bool error = false;
int baud = 115200;
string[] ports = SerialPort.GetPortNames();
foreach (string port in ports)
{
try
{
comPort.PortName = port;
comPort.BaudRate = baud; //convert Text to Integer
comPort.Open();
comPort.DtrEnable = true;
comPort.DataReceived += SerialPortDataReceived;
System.Windows.MessageBox.Show(port.ToString());
}
catch (InvalidOperationException e)
{
System.Windows.MessageBox.Show("");
}
}
}
I know it can be dangerous and poor programing practice to open ALL com ports that are not mine, so my end goal is to open each com port and write some string like "ID_DEVICE" which will then prompt a response from the firmware of the device I am trying to connect to (Arduino). If the com port does not have a proper response then my application will close that specific port and only leave open the ports that had the proper response.
I think John is right, you have to instanciate a new serial port for each port name. If you register an event, don't forget to unsubscribe. F.e. you can store the open comports in an collection to be able to close, deregister the event and dispose the serial port.
I want to check if a Serial port is disconnected or not after clicking a button in C# WinForms.
Eg:
private void btn_Click()
{
if("code to check device disconnected")
{
Do this;
}
else
{
Do this;
}}
PS: Is there any way to check that the device is disconnected when the application is running.
SerialPinchanged, ErrorRecieved, DataRecieved don't help.
Thank you in advance
It depends on the specifications of the target device connected to the COM port.
For example, if RTS/CTS or DTR/DSR are cross-connected, or if the device equivalent to a modem has a DCD or RI valid signal line, and the CTS/DSR/DCD/RI signal line shows valid connection information. , There may be a case where there is a command/response specification for health check or keep alive.
As an alternative, if the COM port is a USB Serial converter, you can check whether or not the device with the corresponding VID and PID exists, but make sure that the device is actually connected at the end of the converter. There is no guarantee.
It is simple logic that whenever SerialPort is disconnected, serialPort.IsOpen turns to false.
private void btn_Click()
{
if(!SerialPort.IsOpen)//If SerialPort is not open
{
Do this;
}
else//Else if SerialPort is open
{
Do this;
}
}
I have an issue with opening an STMicro USB virtual COM port.
When I plug the device into my PC, the COM port appears as it should, and the Windows Device Manager indicates it is working properly.
I have a C# program on the PC which selects and opens this port.
However, in about 1 in 10 attempts, the PC program sticks on the port.open() command, and after about half a minute, returns with the error "The semaphore timeout period has expired".
I have written a tiny C# program that does nothing more than open the port. This still gives the behaviour noted.
public partial class Form1 : Form
{
SerialPort port = new SerialPort();
string portName = "COM1"; // Give it a default to start with
public Form1()
{
InitializeComponent();
// Populate the COM port selector combobox with available port names
cmbPortSelect.Items.Clear();
string[] activePorts = SerialPort.GetPortNames();
foreach (string availablePort in activePorts)
{
cmbPortSelect.Items.Add(availablePort);
}
// Declare the serial port
port = new SerialPort(portName, 9600, Parity.None, 8, StopBits.One);
port.ReadTimeout = 100;
}
private void cmbPortSelect_SelectedIndexChanged(object sender, EventArgs e)
{
if (cmbPortSelect.SelectedIndex != -1)
{ // It will get set to -1 (i.e. no selection) in the catch below - we don’t want this selected item change to do anything
if (port.IsOpen) port.Close();
port.PortName = (string)cmbPortSelect.SelectedItem;
System.Threading.Thread.Sleep(50);
try
{
port.Open();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
cmbPortSelect.SelectedIndex = -1; // Clear the selected item box
}
}
}
}
If instead of using my C# program to open the port, I use the communications program PuTTY, it works every time.
In addition, if I plug in a device with an FDTI USB virtual COM port, it also works every time.
I'm using Windows 7, with the STMicro VCP drivers ver 1.3.1, but the same behaviour occurs with Windows 10 and the generic Microsoft drivers, which STMicro recommend we use.
There is a version 1.5.1 drivers for Windows 7, but when I installed them, it reported that they had installed correctly, but the Device Manager still reported ver 1.3.1.
Has anyone noted any similar behaviour?
That is seemed to be a timing issue. Try to increase your delay from 50 to, say, 200 ms and check the difference. As the doc says: The best practice for any application is to wait for some amount of time after calling the Close method before attempting to call the Open method, as the port may not be closed instantly., sadly, there is no actual time specified.
I'm making a program which communicates with a serial port(RS232 mainly but in this instance I'm using a usb device). Right now I'm having a problem when enabling DTR.
private void CheckBox_DTR_CheckedChanged(object sender, EventArgs e)
{
if(COMport != null)
{
if (CheckBox_DTR.Checked)
{
COMport.DtrEnable = true;
}
else
{
COMport.DtrEnable = false;
}
}
}
In this part of my code I'm enabling DTR if checkbox gets checked. When I checked the pin voltage everything seems to be ok because voltage increases when I enable it. But there's the problem: when I enable DTR using other terminals the device throws out some info but when I do this with my program it doesn't send that info.
My program
Other Serial Terminal
As you can see other terminal has some additional info that device sends out upon enabling DTR. So I'm not completely sure what should I do to receive that info from the device(do I need some additional code or something)...
Generally, when using DTR you need to turn hardware handshaking on. I would try setting COMport.Handshake = Handshake.XOnXOff;.
According to MSDN here:
Data Terminal Ready (DTR) is typically enabled during XON/XOFF software handshaking and Request to Send/Clear to Send (RTS/CTS) hardware handshaking, and modem communications.
I try to search my serial port of my GPS on my tablet (Windows CE).
I know that this is on "COM 3" but I want the program to find this by itself. I mean run in a loop (for) on all ports and search for this.
My question is which "if" I need to write to tell the program "this is my GPS port".
Thank you all.
Gps as i know works with a physical or virtual serial com port (ie com via usb). Since only one application can open a com port at a time there should be no program using gps while searching for the gps-port.
You already gave the answer "loop (for) on all ports and serche for".
Note the example below is an untested scetch how it could work. Feel free to update this wiki page to fix possible errors and add missing functionality.
public string FindGpsPort()
{
foreach(string portname in System.IO.Ports.SerialPort.GetPortNames())
{
// using to make shure that the testport is closed after test
using (SerialPort testport = new SerialPort(){PortName = portname})
{
// maybe neccessary to set baudrate, parity, ... of com port
testport.Open();
// to do if error or exception this is not the
// gps port or some software already uses the gps-port
// to do: read some data from port and verify if it is GPS-Data
// if valid return portname ;
}
}
// All com ports tried but not found. throw exception or return error code
return null;
}