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Preveting computer from going to sleep with program C# [duplicate]

I have to stop windows from going into sleep when my program is running.
And I don't only want to prevent the sleep-timer, I also want to cancel the sleep-event if I press the sleep-button or in any other way actively tell the computer to sleep. Therefore SetThreadExecutionState is not enough.
Or...I don't actually have to prevent the sleep completely, only delay it 5-10sec to allow my program to finish a task.
(I know that this is bad program behavior but it's only for personal use.)

After considering vim's answer
"Using PowerCreateRequest, PowerSetRequest, and PowerClearRequest
functions is the preferred method."
with the linked AvailabilityRequests.docx on msdn which is exhausting to get into it (too much to read), I have searched the web for a concrete example in c# that is based on the PowerCreateRequest and found http://go4answers.webhost4life.com/Example/problem-monitor-wakeup-service-windows7-12092.aspx [EDIT 2016 - isn't available anymore]
Copied and adapted it to my needs (PInvoke of CloseHandle copied from msdn):
using System.Runtime.InteropServices;
#region prevent screensaver, display dimming and automatically sleeping
POWER_REQUEST_CONTEXT _PowerRequestContext;
IntPtr _PowerRequest; //HANDLE
// Availability Request Functions
[DllImport("kernel32.dll")]
static extern IntPtr PowerCreateRequest(ref POWER_REQUEST_CONTEXT Context);
[DllImport("kernel32.dll")]
static extern bool PowerSetRequest(IntPtr PowerRequestHandle, PowerRequestType RequestType);
[DllImport("kernel32.dll")]
static extern bool PowerClearRequest(IntPtr PowerRequestHandle, PowerRequestType RequestType);
[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]
internal static extern int CloseHandle(IntPtr hObject);
// Availablity Request Enumerations and Constants
enum PowerRequestType
{
PowerRequestDisplayRequired = 0,
PowerRequestSystemRequired,
PowerRequestAwayModeRequired,
PowerRequestMaximum
}
const int POWER_REQUEST_CONTEXT_VERSION = 0;
const int POWER_REQUEST_CONTEXT_SIMPLE_STRING = 0x1;
const int POWER_REQUEST_CONTEXT_DETAILED_STRING = 0x2;
// Availablity Request Structures
// Note: Windows defines the POWER_REQUEST_CONTEXT structure with an
// internal union of SimpleReasonString and Detailed information.
// To avoid runtime interop issues, this version of
// POWER_REQUEST_CONTEXT only supports SimpleReasonString.
// To use the detailed information,
// define the PowerCreateRequest function with the first
// parameter of type POWER_REQUEST_CONTEXT_DETAILED.
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct POWER_REQUEST_CONTEXT
{
public UInt32 Version;
public UInt32 Flags;
[MarshalAs(UnmanagedType.LPWStr)]
public string
SimpleReasonString;
}
[StructLayout(LayoutKind.Sequential)]
public struct PowerRequestContextDetailedInformation
{
public IntPtr LocalizedReasonModule;
public UInt32 LocalizedReasonId;
public UInt32 ReasonStringCount;
[MarshalAs(UnmanagedType.LPWStr)]
public string[] ReasonStrings;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct POWER_REQUEST_CONTEXT_DETAILED
{
public UInt32 Version;
public UInt32 Flags;
public PowerRequestContextDetailedInformation DetailedInformation;
}
#endregion
/// <summary>
/// Prevent screensaver, display dimming and power saving. This function wraps PInvokes on Win32 API.
/// </summary>
/// <param name="enableConstantDisplayAndPower">True to get a constant display and power - False to clear the settings</param>
private void EnableConstantDisplayAndPower(bool enableConstantDisplayAndPower)
{
if (enableConstantDisplayAndPower)
{
// Set up the diagnostic string
_PowerRequestContext.Version = POWER_REQUEST_CONTEXT_VERSION;
_PowerRequestContext.Flags = POWER_REQUEST_CONTEXT_SIMPLE_STRING;
_PowerRequestContext.SimpleReasonString = "Continuous measurement"; // your reason for changing the power settings;
// Create the request, get a handle
_PowerRequest = PowerCreateRequest(ref _PowerRequestContext);
// Set the request
PowerSetRequest(_PowerRequest, PowerRequestType.PowerRequestSystemRequired);
PowerSetRequest(_PowerRequest, PowerRequestType.PowerRequestDisplayRequired);
}
else
{
// Clear the request
PowerClearRequest(_PowerRequest, PowerRequestType.PowerRequestSystemRequired);
PowerClearRequest(_PowerRequest, PowerRequestType.PowerRequestDisplayRequired);
CloseHandle(_PowerRequest);
}
}

I had a problem like this with a hardware device connected via usb. XP /Vista would sleep/hibernate right in the middle of ... Great you say, when it resumes it can just continue. If the hardware is still connected!!!
Users have the habit of pulling cables out whenever they feel like it.
You need to handle XP and Vista
Under XP trap the WM_POWERBROADCAST and look for the PBT_APMQUERYSUSPEND wparam.
// See if bit 1 is set, this means that you can send a deny while we are busy
if (message.LParam & 0x1)
{
// send the deny message
return BROADCAST_QUERY_DENY;
} // if
else
{
return TRUE;
} // else
Under Vista use SetThreadExecutionState like this
// try this for vista, it will fail on XP
if (SetThreadExecutionState(ES_CONTINUOUS | ES_SYSTEM_REQUIRED | ES_AWAYMODE_REQUIRED) == NULL)
{
// try XP variant as well just to make sure
SetThreadExecutionState(ES_CONTINUOUS | ES_SYSTEM_REQUIRED);
} // if
and when you app has finished set it back to normal
// set state back to normal
SetThreadExecutionState(ES_CONTINUOUS);

Using PowerCreateRequest, PowerSetRequest, and PowerClearRequest functions is the preferred method. Details and sample code (C/C#) are inside http://msdn.microsoft.com/en-us/library/windows/hardware/gg463205.aspx

set wsc = CreateObject("WScript.Shell")
Do
WScript.Sleep (60*1000)
wsc.SendKeys ("{SCROLLLOCK 2}")
Loop
-put the above code in notepad and save the file as .vbs and double click the file

The same technique applies as for preventing the screensaver should be used. See Programmatically prevent Windows screensaver from starting.
Note that some security settings can override this (forcing computers to lock after a certain time is one).

If you need a display that should work until your application is running then try to set "ES_DISPLAY_REQUIRED" instead of away mode:
SetThreadExecutionState(ES_CONTINUOUS | ES_SYSTEM_REQUIRED | ES_DISPLAY_REQUIRED);
Once you are done with your application make sure to clear all other flags.
SetThreadExecutionState(ES_CONTINUOUS);

How about waking it back up if it goes to sleep?
http://www.enterprisenetworksandservers.com/monthly/art.php?1049

Below is my attempt using the modern power availability request API (supersedes SetThreadExecutionState), as suggested by vim.
I'm using a nice P/Invoke NuGet I came across, Vanara.PInvoke.Kernel32:
using Vanara.PInvoke;
using static Vanara.PInvoke.Kernel32;
// create request object
using var request = PowerCreateRequest(new REASON_CONTEXT("App FOO is working"));
if (request.IsInvalid)
{
throw new InvalidOperationException(
$"Could not create power availability request: {Win32Error.GetLastError()}");
}
// send request
if (!PowerSetRequest(request, POWER_REQUEST_TYPE.PowerRequestSystemRequired))
{
throw new InvalidOperationException(
$"Could not send power availability request: {Win32Error.GetLastError()}");
}
// do stuff that required the machine to be up
Console.WriteLine("Doing stuff...");
await Task.Delay(5000);
// clear request
if (!PowerClearRequest(request, POWER_REQUEST_TYPE.PowerRequestSystemRequired))
{
Console.WriteLine(
"WARNING: Could not clear power availability request: {0}",
Win32Error.GetLastError());
}
You can see your request in action by issuing powercfg /requests from an admin terminal.

Listing all Smart Card Readers on a system (Alcor Micro reader issues)

I've had this software running in production for years and never seen this problem before. I just received a new laptop (HP EliteBook 8470p) that has a built-in Alcor Micro USB Smart Card Reader.
The code below will list all readers on a system and seems to work fine. Some of our systems will have 3 or 4 readers plugged in to a single computer. It's been tested with a dozen or so models with no issues.
Strangely, the Alcor reader will only get listed when a Smart Card is inserted. If I look at it in Device Manager, it doesn't show up under the "Smart card readers" until a card is inserted, too (unless I go to View > Show Hidden Devices).
Does anyone know why this is or if there's a way to make sure it gets listed in my software?
Thank you.
The code:
[DllImport("WINSCARD.DLL", EntryPoint = "SCardEstablishContext", CharSet = CharSet.Unicode, SetLastError = true)]
static internal extern uint EstablishContext(ScopeOption scope, IntPtr reserved1,
IntPtr reserved2, ref SmartcardContextSafeHandle context);
[DllImport("WINSCARD.DLL", EntryPoint = "SCardListReaders", CharSet = CharSet.Unicode, SetLastError = true)]
static internal extern uint ListReaders(SmartcardContextSafeHandle context, string groups,
string readers, ref int size);
private bool EstablishContext()
{
if ((this.HasContext))
{
return true;
}
this._lastErrorCode =
(SmartcardErrorCode)UnsafeNativeMethods.EstablishContext(ScopeOption.System,
IntPtr.Zero, IntPtr.Zero, ref this._context);
return (this._lastErrorCode == SmartcardErrorCode.None);
}
public ArrayList ListReaders()
{
ArrayList result = new ArrayList();
//Make sure a context has been established before
//retrieving the list of smartcard readers.
if (this.EstablishContext())
{
//Ask for the size of the buffer first.
int size = this.GetReaderListBufferSize();
//Allocate a string of the proper size in which
//to store the list of smartcard readers.
string readerList = new string('\0', size);
//Retrieve the list of smartcard readers.
this._lastErrorCode =
(SmartcardErrorCode)UnsafeNativeMethods.ListReaders(this._context,
null, readerList, ref size);
if ((this._lastErrorCode == SmartcardErrorCode.None))
{
//Extract each reader from the returned list.
//The readerList string will contain a multi-string of
//the reader names, i.e. they are seperated by 0x00
//characters.
string readerName = string.Empty;
for (int i = 0; i <= readerList.Length - 1; i++)
{
if ((readerList[i] == '\0'))
{
if ((readerName.Length > 0))
{
//We have a smartcard reader's name.
result.Add(readerName);
readerName = string.Empty;
}
}
else
{
//Append the found character.
readerName += new string(readerList[i], 1);
}
}
}
}
return result;
}
Btw, this code was written by someone else who I'm guessing (by the over-abundance of comments) found it somewhere else online. I'm somewhat familiar with it but never gotten too deep into it. I've tried making several tweaks to it and can't get it to list that Alcor reader at all.
Thanks!

Ok, I feel really stupid finding the answer immediately after opening the bounty. I spent a while looking at this from a software perspective and gave up for a while - when I came back to revisit this I decided it might be suited for a bounty.
I decided to take a closer look at my BIOS options, and guess what? There's an option in there that says "Power on Smart Card Reader: a) when card is inserted, b) always". I changed it to "Always" and it works. ARGH
It won't let me delete my question since it has a bounty now, but that's basically my answer. Thanks for the comments/advice.

controlling a physical device via c# [closed]

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Closed 10 years ago.
I want to control a physical device. ie: blink some LEDs or turn a servo. (just so simple that I will connect my LED's legs to USB's legs or serial ports pins and send a signal to one of the LED's leg and lit it and same with a servo.)
Question: How can I make this in C#? How can i send a signal through either usb or serial port? What are the things that I need? and how can I manage it? thanks.
messageBox.Show("How to control a physical device via c# ?");
messageBox.Show("thanks");

You can use Your serial port like this:
SerialPort port = new SerialPort("COM1", 2400, Parity.None, 8, StopBits.One);
port.Open();
port.Write(new byte[] {0x00, 0xFF, 0xFF}, 0, 3);
port.Close();
The whole thing will be send bit by bit on one wire on serial port and with additional bits for transmission control.
You can blink LED with this. You need to connect LED to pin Transmit Data and to Ground that is usually the plug cover or one of pins. Check this for reference. You need also resistor to lower the current. 3k [ohm] resistor should do.
Driving small servo motor is possible but not that easy. Its better to control servo with microcontroller connected to Your computer.
You can connect two computers and exchange data with this.
You can burn Your equipment so be careful.
You can also buy or build something like this
EDIT:
Ok, lots of questions.
QUESTION 1) why its hard? cant i just send a signal to the servo and
make it run just like i did on the LED?
Serial port is a communication port so its purpose is to communicate and NOT to drive equipment. Its power capabilities are low. This port will store data to send in buffer and send bit by bit. So its extremely hard to shape PWM \ PPM signal to drive servo and after all result are not gonna be brilliant as well. Depending on motor that You have You may need other control method, but it will be hard to implement with serial port as well. If You really want to drive hardware from a port I would advice parallel port.
QUESTION 2) in which cases i burn my equipment? and do u mean i burn my serial port? or i burn LED or the servo?
QUESTION 3) you said "Your PC should also have current limited output"
so as you referred if i put a resistor then i can manage this? and
does 3k solves in all case?
In case You do not know enough about electrical circuits, networks and analysis then You have big chance to damage Your equipment. You can burn all of them and in worst case scenario also Your PC and house! First two problems that You need to worry about are short circuit and electrostatic discharge
Current limited output should lower current when resistors value is too low. This should prevent the damage of serial port driver on mainboard of PC.
3k resistor complies with serial port specification requirements (3-7[kOhm] <2500[pF]). It should drop taken current below 4[mA]. So in theory it should solve all cases.
QUESTION 4) where will i write your code? in to the button1 clicked? i mean lest say i have a winform and a button there, will i write your code in to the button clicked event?
You can open port on opening Your program. Then write to port on button click. Then close port on close program. All the code on button click should work as well.
PS.: Its also possible to connect serial port to audio input of sound card and then send data on serial port and record it as audio. It works as simple oscilloscope. (You can damage Your PC with this)

You need a device that will translate your USB signals to signals your device understands (likely a simple on or off for LED's).
I have used the U421 in the past, they have a library that you just load the DLL using P/Invoke then you can send signals to the pins on the chip. You will then need to wire whatever you want to control to the chip (correctly, but that is beyond the scope of Stack Overflow, you may want to try Electronics.StackExchange.com). See the U4x1 Application Notes section on the USBMicro website for example code and wiring diagrams.
Example code from the webiste:
⁄⁄ needed to import the .dll
using System.Runtime.InteropServices;
public class USBm
{
public static byte BitA0 = 0x00;
public static byte BitA1 = 0x01;
public static byte BitA2 = 0x02;
public static byte BitA3 = 0x03;
public static byte BitA4 = 0x04;
public static byte BitA5 = 0x05;
public static byte BitA6 = 0x06;
public static byte BitA7 = 0x07;
public static byte BitB0 = 0x08;
public static byte BitB1 = 0x09;
public static byte BitB2 = 0x0A;
public static byte BitB3 = 0x0B;
public static byte BitB4 = 0x0C;
public static byte BitB5 = 0x0D;
public static byte BitB6 = 0x0E;
public static byte BitB7 = 0x0F;
⁄⁄ USBm.dll - C# pInvoke examples
⁄⁄ "Commands"
⁄⁄ [DllImport("USBm.dll", EntryPoint = "USBm_FindDevices", CharSet = CharSet.Auto)]
[DllImport("USBm.dll")]
public static extern bool USBm_FindDevices();
[DllImport("USBm.dll")]
public static extern int USBm_NumberOfDevices();
[DllImport("USBm.dll")]
public static extern bool USBm_DeviceValid(int Device);
[DllImport("USBm.dll")]
public static extern bool USBm_About(StringBuilder About);
[DllImport("USBm.dll")]
public static extern bool USBm_Version(StringBuilder Version);
[DllImport("USBm.dll")]
public static extern bool USBm_Copyright(StringBuilder Copyright);
[DllImport("USBm.dll")]
public static extern bool USBm_DeviceMfr(int Device, StringBuilder Mfr);
[DllImport("USBm.dll")]
public static extern bool USBm_DeviceProd(int Device, StringBuilder Prod);
[DllImport("USBm.dll")]
public static extern int USBm_DeviceFirmwareVer(int Device);
[DllImport("USBm.dll")]
public static extern bool USBm_DeviceSer(int Device, StringBuilder dSer);
[DllImport("USBm.dll")]
public static extern int USBm_DeviceDID(int Device);
[DllImport("USBm.dll")]
public static extern int USBm_DevicePID(int Device);
[DllImport("USBm.dll")]
public static extern int USBm_DeviceVID(int Device);
[DllImport("USBm.dll")]
public static extern bool USBm_DebugString(StringBuilder DBug);
[DllImport("USBm.dll")]
public static extern bool USBm_RecentError(StringBuilder rError);
[DllImport("USBm.dll")]
public static extern bool USBm_ClearRecentError();
[DllImport("USBm.dll")]
public static extern bool USBm_SetReadTimeout(uint TimeOut);
[DllImport("USBm.dll")]
public static extern bool USBm_ReadDevice(int Device, byte[] inBuf);
[DllImport("USBm.dll")]
public static extern bool USBm_WriteDevice(int Device, byte[] outBuf);
[DllImport("USBm.dll")]
public static extern bool USBm_CloseDevice(int Device);
}
Example of function calling
⁄⁄ Test USBm device attached
if ( !USBm.USBm_FindDevices() )
{
MessageBox.Show( string.Format("No Device Present"), "USBm Devices", MessageBoxButtons.OK, MessageBoxIcon.Information );
return;
} ⁄⁄ implied else
⁄⁄Walk the USBm.dll functions
⁄⁄ some containers
StringBuilder sb = new StringBuilder( 200 );
bool result = false; ⁄⁄ return values
⁄⁄ .DLL FindDevices returns the number of devices
result = USBm.USBm_FindDevices();
⁄⁄ return the number of devices
int TotalDevices = USBm.USBm_NumberOfDevices();
int Device = TotalDevices -1; ⁄⁄ only One device is ever attached so ...
⁄⁄ .DLL About info
result = USBm.USBm_About( sb );
⁄⁄ .DLL Version info
result = USBm.USBm_Version( sb );
⁄⁄ .DLL Copyright info
result = USBm.USBm_Copyright( sb );
⁄⁄ Device Valid
result = USBm.USBm_DeviceValid( Device );
⁄⁄ Device Manufacturer
result = USBm.USBm_DeviceMfr( Device, sb );
⁄⁄ Device Product String
result = USBm.USBm_DeviceProd( Device, sb );
⁄⁄ Device Firmware Version
int FirmVer = USBm.USBm_DeviceFirmwareVer(Device);
⁄⁄ Device SerialNumber [ ]
result = USBm.USBm_DeviceSer(Device, sb);
⁄⁄ Device DiD
int DID = USBm.USBm_DeviceDID(Device);
⁄⁄ Device PiD
int PID = USBm.USBm_DevicePID(Device);
⁄⁄ Device ViD
int VID = USBm.USBm_DeviceVID(Device);
⁄⁄ Device Debug String
result = USBm.USBm_DebugString(sb);
⁄⁄ Device Recent Error - always returns true
result = USBm.USBm_RecentError(sb);
⁄⁄ Device Clear Recent Error
result = USBm.USBm_ClearRecentError();
⁄⁄ Device SetReadTimeout [ sixteen-bit millisecond value]
uint tOUT = 3000;
result = USBm.USBm_SetReadTimeout(tOUT);
⁄⁄ Device WriteDevice [ 8 byte to write (device raw commands)]
byte[] OutBuf = { 0, 21, 3, 65, 8, 17, 60, 0 };
result = USBm.USBm_WriteDevice(Device, OutBuf);
⁄⁄ Device ReadDevice [ ]
byte[] InBuf = { 0, 0, 0, 0, 0, 0, 0, 0 };
result = USBm.USBm_ReadDevice(Device, InBuf);
// Device CloseDevice [ ]
result = USBm.USBm_CloseDevice(Device);

C# - Read Parallel Port State (Simple Push Switch)

I am updating in C# some software that was originally written in VC++ V1.0 for DOS6.
One aspect of the software is a check on the parallel port, where a simple push-button switch is connected. I don't currently know to which two pins the switch is connected, but I have the source for the old program, the relevant sections of which are below...
#define switch_mask 0x10
void main(int argc, char *argv[])
{
int NewState = 0, OldState = 0;
/* Check switch */
NewState = _bios_printer (_PRINTER_STATUS, 0, 0);
if (NewState != OldState)
{
checkParallelPort (NewState);
OldState = NewState;
}
}
void checkParallelPort (int portState)
{
int SwitchState;
/* Switch bit is Active LOW */
SwitchState = (portState & switch_mask) ? 1 : 0;
}
Now _bios_printer (within bios.h) is obviously not available to me in C#, but I'm struggling to find an alternative that can do this simple task.
Info on _bios_printer is here. I've done plenty of searching for reading/writing to/from the parallel port in .Net, but nothing seems to provide me with the port status.
Also, can you conclude from this code (and how it checks the 'status') where the two switch wires are connected on the DB25 plug?
I'd be grateful if anyone has some help/advice on this please.
Many thanks

It seems to be checking 'Error', pin 15. IIRC, this is pulled up internally, so your switch should pull down pin 15. Connect it between pins 15 and 18.
There are some drivers available that allow the reading of the I/O map ports. You will have to import and make DLL calls and then almost certainly poll the pin :((
I do wish this interface was dead and buried!

Thanks for the reply. Here's what I ended up with...
I used this tutorial on CodeProject...
http://www.codeproject.com/KB/vb/Inpout32_read.aspx
When converted to C#, I used something similar to below. (Apologies if there is an error - I 'paraphrased' the code below from what i've ended up with - it works for me!)
private void button1_Click(object sender, EventArgs e)
{
short InReg = 0x379; // Location of Port Status register
int NewState; // int named NewState
NewState = InpOut32_Declarations.Inp(InReg); //Now NewState has the values in 'Status port'
MessageBox.Show(NewState); //A popup will indicate the current value of NewState
}
static class InpOut32_Declarations
{
[DllImport("inpout32.dll", EntryPoint = "Inp32", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
//Inp and Out declarations for port I/O using inpout32.dll.
public static extern int Inp(ushort PortAddress);
[DllImport("inpout32.dll", EntryPoint = "Out32", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
public static extern void Out(ushort PortAddress, short Value);
}
Interestingly, as my Parallel Port starts at 0xE800 and not 0x378, I had to modify the source of inpout32.dll as the out32 method only accepts a short and 0xE800 is too big for a short! changed it to unsigned short.
Thanks for your help

SerialPort port.open "The port 'COM2' does not exist."

I'm having a big problem with the SerialPort.Open();
I am communicating with an usb virtual com port (cdc), and it is listed as COM2.
It works fine in TeraTerm/hyperTerminal ect. but when I try to open the port in C#, it gives me the Exception The port 'COM2' does not exist.
I get the port name using the SerialPort.GetPortNames() function, and it looks fine when I debug.
I have tried to set the name hardcoded, but with no luck.
Now the really strange thing, it works fine on some PC's, and fails on other PC's. On some PC's it fail all the time, and on others it fails 10% of the time.
Even more strange it depends on the usb port used, some ports works fine, others fail (on the same PC!).
Could anybody help me please?

I've worked with virtual serial ports before. Oftentimes they aren't accessible as "COMX:" to some windows API calls, and you have to fully specify them. That might be the case here. Try using the Windows device namespace path for the serial device. For example: "\\.\COM2"
Another thing I've found useful for debugging is opening up a Hyperterm on the given serial port.
One final thing: For debugging your logic on systems that don't have all the hardware, I found this wonderful program called com0com. It is a GPL Sourceforge project that creates tied pairs of virtual com ports on your system. Whatever is written to one can be read from the other, and visa versa. You can either write an emulator and give it one of the ports, or just open up Hyperterm on it. Then give the other to your program. Testing with no cables or other hardware required.

This error can be caused if the driver returns an unexpected "file type" for "COM2".
Try p/Invoking GetFileType and I believe you'll see the pattern. It has to be FILE_TYPE_CHAR or FILE_TYPE_UNKNOWN or else SerialPort will throw that exception.
class Program
{
static void Main(string[] args)
{
string portName = #"COM2";
IntPtr handle = CreateFile(portName, 0, 0, IntPtr.Zero, 3, 0x80, IntPtr.Zero);
if (handle == (IntPtr)(-1))
{
Console.WriteLine("Could not open " + portName + ": " + new Win32Exception().Message);
Console.ReadKey();
return;
}
FileType type = GetFileType(handle);
Console.WriteLine("File " + portName + " reports its type as: " + type);
Console.ReadKey();
}
[DllImport("kernel32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall, SetLastError = true)]
public static extern IntPtr CreateFile(string lpFileName, uint dwDesiredAccess, uint dwShareMode, IntPtr SecurityAttributes, uint dwCreationDisposition, uint dwFlagsAndAttributes, IntPtr hTemplateFile);
[DllImport("kernel32.dll")]
static extern FileType GetFileType(IntPtr hFile);
enum FileType : uint
{
UNKNOWN = 0x0000,
DISK = 0x0001,
CHAR = 0x0002,
PIPE = 0x0003,
REMOTE = 0x8000,
}
}
Also see this thread on MSDN forums.