Re: Event handling Object reference error - C# Discussion Boards

How to code in for USB to serial......sending and receiving communication

pallaka20-Jul-09 0:11

pallaka

20-Jul-09 0:11

How to code in for USB to serial......sending and receiving communication

Re: How to code in for USB to serial......sending and receiving communication

Luc Pattyn20-Jul-09 0:40

Luc Pattyn

20-Jul-09 0:40

When I bought my USB-to-serial cable, it came with a CD-ROM containing a driver. When I installed it, it turned the port into a regular serial port, so it shows up in all serial port enumerations, and most/all serial apps can use it, whether HyperTerminal or some .NET based app using SerialPort class.

The app never is aware the USB-based serial port is connected in a different manner, all the nasty details are hidden by Windows and the device drivers.

BTW: there are minor differences between such a USB-to-serial cable and a regular serial port, mainly in timing; it is not able to achieve very high speed in toggling the control lines, which for most applications is irrelevant; if however the attached hardware requires very short pulses on say the DTR/DSR/RTS pins, the motherboard- based serial port might be able to deliver and the USB-to-serial might not, due to the fact USB communication requires data packets, which must be transmitted and interpreted, whereas a direct port is much "closer" to the CPU.

Smile | :)

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Enterprise application Development (MCPD)

Abdul Rahman Hamidy20-Jul-09 0:03

Abdul Rahman Hamidy

20-Jul-09 0:03

Dear All, I know this hasn't to do any thing with C# forum, but as you people are expert in programming section.
i have a question. well i decided to take MCPD enterprise application development certification
i am asking u guys about a good institute or university in India, UK?

yours really appreciated

Abdul Rahaman Hamidy
Database Developer
Kabul, Afghanistan

Multi client - Server application

Tej Aj19-Jul-09 23:42

Tej Aj

19-Jul-09 23:42

I want to create a desktop application having a single centralized server
which accepts multiple client connections and responds them.

I am trying to use TcpListener class (for server) and TcpClient class (for clients). The server and client application are able to connect but I am not able to accept multiple clients connections.

Can anyone help me out to solve this issue.

Re: Multi client - Server application

stancrm19-Jul-09 23:58

stancrm

19-Jul-09 23:58

Multi-threaded .NET TCP Server Examples[^]

Event handling Object reference error

gwithey19-Jul-09 22:44

gwithey

19-Jul-09 22:44

I am trying to create an on update event and have recieved the following error:

An object reference is required for the non-static field, method, or property 'RenishawVMCU.CommandParser.OnUpdate(RenishawVMCU.CommandData)'

It is generated form this line: OnUpdate(rxPortData);

public class CommandParser
   {
      CommandData rxPortData = new CommandData();


public delegate void delUpdate(CommandData commandData);
      public event delUpdate update;
      
      protected virtual void OnUpdate(CommandData commandData)
      {
         if (update != null)
         {
            this.update(commandData);
         }
      }
}
 public static string ParseCommand(string m_recievedUCCData)
      {         
         byte[] rxData;

         rxData = StrToByteArray(m_recievedUCCData);

         //CommandData rxPortData = new CommandData();
         CommandData rxPortData = ParseCommand(rxData);

         //OnUpdate(rxPortData);

         rxData.ToString();
         return "Parsing done!" ;
        
      }


public class VirtualMCU
   {
public VirtualMCU()
      {
         cmdParser.update += new CommandParser.delUpdate(cmdParser_update);
      }
}

Does anyone know what could be wrong as this is the only line that is causing a problem i cant work it out.

Re: Event handling Object reference error

Uri Lavi19-Jul-09 22:49

Uri Lavi

19-Jul-09 22:49

ParseCommand is a static method.
You cannot access non static methods / members from the static one.

Uri

Re: Event handling Object reference error

DaveyM6919-Jul-09 23:04

DaveyM69

19-Jul-09 23:04

This is static

public static string ParseCommand(string m_recievedUCCData)
{
    // ...
    OnUpdate(rxPortData);
    // ...
}

This is not so can only be called by an instance of CommandParser

protected virtual void OnUpdate(CommandData commandData)
{
    // ...
}

If there is no particular reason for the ParseCommand method to be static, then make it an instance member. Alternatively, pass a CommandParser instance as a parameter into the ParseCommand method and act on that.

public static string ParseCommand(string m_recievedUCCData, CommandParser commandParser)
{
    // ...
    commandParser.OnUpdate(rxPortData);
    // ...
}

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)
Why are you using VB6? Do you hate yourself? (Christian Graus)

Re: Event handling Object reference error

gwithey19-Jul-09 23:24

gwithey

19-Jul-09 23:24

Thanx for the help. I had not yet learnt of this so was useful information.

i soleved the probelm by passing in the perameter as you suggested which stopped the error.

This is the final code, it didnt have a problem with calling Parsecommand(byte[]) as the method is static.

public static string ParseCommand(string m_recievedUCCData, CommandParser commandParser)
     {
        byte[] rxData;

        rxData = StrToByteArray(m_recievedUCCData);

        CommandData rxPortData = ParseCommand(rxData);

        commandParser.OnUpdate(rxPortData);

        //rxData.ToString();
        return "Parsing done!" ;

     }

Re: Event handling Object reference error

Luc Pattyn20-Jul-09 0:46

Luc Pattyn

20-Jul-09 0:46

Here[^] is a hint for you.

Smile | :)

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Impersonation

arkiboys19-Jul-09 21:37

arkiboys

19-Jul-09 21:37

Hi,
Created a user i.e. UserA in the domain.
Added this user to the administrators group in serverA.
Using C#, I impersonate this user in my application.
Then using UserA, the application creates a vbscript on ServerA.
Problem is that the vbscript does not get run when I use the processstart call
The error is vbscript engine is not found.
Please note that if I log into the application using my credentials then all works fine and the script runs correctly on serverA.
Do you know why I get the below error if logged in as UserA?
I have also run regsvr32 vbscript on serverA but this does not help in the case of UserA

Error is:
Can not find script engine vbscript for script "path of the vbscript".

Thanks

compress bytes

shekhar25839519-Jul-09 21:35

shekhar258395

19-Jul-09 21:35

hi i can convert an image(in picturebox) in bytes nw i want to compress it hw can i compress it

Re: compress bytes

0x3c019-Jul-09 21:41

0x3c0

19-Jul-09 21:41

Read it into a MemoryStream. Then compress it using the System.IO.Compression.GZipStream class. You could also use the #ZipLib library - there is an article on this site about it (MemoryStream Compression[^])

Between the idea
And the reality
Between the motion
And the act
Falls the Shadow

Most efficient way of taking a screenshot? [modified]

Trapper-Hell19-Jul-09 21:15

Trapper-Hell

19-Jul-09 21:15

The Subject says it all... At the moment I am using the following method:

Bitmap bmpScreenshot = new Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height, PixelFormat.Format32bppArgb);

Graphics gfxScreenshot = Graphics.FromImage(bmpScreenshot);

gfxScreenshot.CopyFromScreen(Screen.PrimaryScreen.Bounds.X, Screen.PrimaryScreen.Bounds.Y, 0, 0, Screen.PrimaryScreen.Bounds.Size, CopyPixelOperation.SourceCopy);

However, since I need to be taking screenshots at around every 250ms, I need to find the most efficient way possible (if any)...

Thanks!

Note: I have found that taking partial parts of the screen is much more efficient, but at the moment I need all the screen taken...

modified on Monday, July 20, 2009 3:22 AM

repost. ignore.

Luc Pattyn20-Jul-09 0:49

Luc Pattyn

20-Jul-09 0:49

here[^]

Luc Pattyn [Forum Guidelines] [My Articles]

The quality and detail of your question reflects on the effectiveness of the help you are likely to get.
Show formatted code inside PRE tags, and give clear symptoms when describing a problem.

Re: repost. ignore.

Trapper-Hell20-Jul-09 2:31

Trapper-Hell

20-Jul-09 2:31

I must say that that was really helpful...

convert image in bytes

shekhar25839519-Jul-09 20:57

shekhar258395

19-Jul-09 20:57

hi i m shekhar i having an image tht stored in picturebox i want to convert this image in to bytes plz help me

Re: convert image in bytes

stancrm19-Jul-09 21:12

stancrm

19-Jul-09 21:12

MemoryStream ms = new MemoryStream();
pictureBox1.Image.Save(ms, ImageFormat.Jpeg);
byte[] data = ms.ToArray();
ms.Close();

Trace.Write(data);

picturebox help

mjawadkhatri19-Jul-09 20:48

mjawadkhatri

19-Jul-09 20:48

Hi..
i take one lebal store text in lebel like E:\Epic\ + textbox1.text + .jpg user type in textbox "1" so label.text is = E:\Epic\1.jpg now i want this location pic show in picbox, user type in textbox 2 then show 2.jpg.
Hope u understand my question.

take care
Thanks In Advnc

jawad khatri

Re: picturebox help

PandemoniumPasha19-Jul-09 21:47

PandemoniumPasha

19-Jul-09 21:47

from what i understand, you want to display the image in the picture box. there should be a Load function for the purpose.
you can do something like:

picturebox1.Load("image path here");

HTH

regards

Re: picturebox help

mjawadkhatri19-Jul-09 21:49

mjawadkhatri

19-Jul-09 21:49

my image path is in lebal

picturebox1.Load(label1.text);
i can do this????

Re: picturebox help

PandemoniumPasha19-Jul-09 21:51

PandemoniumPasha

19-Jul-09 21:51

mjawadkhatri wrote:
my image path is in lebal

picturebox1.Load(label1.text);
i can do this????

yes, of course.

regards

Re: picturebox help

mjawadkhatri19-Jul-09 22:14

mjawadkhatri

19-Jul-09 22:14

yes I have Done Thanks Alot

import contacts from hotmail using c#

Charan Pat19-Jul-09 20:48

Charan Pat

19-Jul-09 20:48

Hi All,

I would like to have the code in c# that will import all my contacts of hotmail and AOL into my local database by passing respective credentials.

Any quick help would be really appreciated

Thanks,
Cj

Re: import contacts from hotmail using c#

Ashfield19-Jul-09 21:37

Ashfield

19-Jul-09 21:37

Have you visited the hotmail and aol sites to see what apis are available? That should be your starting point.

Bob
Ashfield Consultants Ltd
Proud to be a 2009 Code Project MVP

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