C# Discussion Boards - CodeProject

Re: Prob with SerialPort ReadExisting method

5-May-07 3:27

I've been trying to a simple Comm program to work using the
ReadExisting method of the .Net 2.0 SerialPort class.
The data is being transmitted to me from a PIC micro dev board.

The data received event fires when ReceivedBytesThreshold is
reached as it should, but I only get back one character when there are
4 in the buffer. I verified this by retrieving the BytesToRead
property and it is set to 4.

If I add additional ReadExisting method calls afterwards I will get
one and only one char back for each read.

I also tried the Read method but same result as ReadExisting.

Lastly I ran Hyperterm and another terminal program
and they both receive the entire 4 chars with no problems.
The databits, baudrate, and handshaking are all set the same
for my code as well as the terminal programs. I have also
tried setting the DtrEnable and RtsEnable to true but with
no success.

sorry for the long post but i tried to be as brief as possible

Any help will be greatly appreciated.

Luc Pattyn5-May-07 3:39

Re: Prob with SerialPort ReadExisting method

5-May-07 3:39

Hi, since ReadExisting reads bytes but returns a string, I would guess you have a problem with
the encoding. Why dont you use Read(byte[],...) ?

Smile | :)

Luc Pattyn

[My Articles]

sew44125-May-07 10:15

Tried and got same behaviour, Ideas?

5-May-07 10:15

Its possible but then why do the successive ReadExisting invocations
return the characters that were sent? I will give it a try.

sew44126-May-07 2:40

Re: Tried and got same behaviour, Ideas?

6-May-07 2:40

Stan

Luc Pattyn6-May-07 4:01

Debugger affecting reception of data

6-May-07 4:01

Hi,

SerialPort.Read documentation contains following note:
"Because the SerialPort class buffers data, and the stream contained in the BaseStream property does not, the two might conflict about how many bytes are available to read. The BytesToRead property can indicate that there are bytes to read, but these bytes might not be accessible to the stream contained in the BaseStream property because they have been buffered to the SerialPort class."

If you want specific help, show all code involved + port settings + actual bytes received.

Smile | :)

Luc Pattyn

[My Articles]

sew44127-May-07 2:50

VS.NET, Winform default settings

7-May-07 2:50

I understand the documentation but that does not explain why I never got
the data. It would explain it if I only checked one time.

I ran the release version of .exe and I receive data without any changes to
existing code. However the reception rate is very slow compared to
something like hyperterm. I ran another Serial Terminal program
that I downloaded from an article on CodeProject and it does the same
thing. I think I may need to play with the read timeouts. So far
Im not very impressed with .Net's support for serial ports. [rant] I have
probably done something similiar to this at least 10 times before
on other platforms or development environments including Visual C++
and never had so much trouble. [end of rant]

Imtiaz Murtaza5-May-07 3:22

Imtiaz Murtaza

5-May-07 3:22

Dear Friends,
What i want is that whenever i add new form in my application using Visual studio, it should appear in some different color and contains some different icon than what VS adds in default. Plz tell me how

Imtiaz

Re: VS.NET, Winform default settings

subai5-May-07 3:56

subai

5-May-07 3:56

hi i'm not sure that i got your question but may you can use visual studio templates
then you can add your custom form in 'Add' dialog box instead traditional windows form

I Wish the Life Had CTRL-Z

Preserve creation date

electriac5-May-07 3:08

5-May-07 3:08

How can I copy a file and preserve the creation date?

subai5-May-07 4:02

subai

5-May-07 4:02

i know a trick with MS-Dos command prompt but i think it will not be usefull for you
however if you didn't find your answer try System.IO.Directory.SetCreationTime
as your last solution

I Wish the Life Had CTRL-Z

Luc Pattyn5-May-07 6:42

5-May-07 6:42

Hi,

Explorer when copying a file sets creation time current,
but preserves last modified time (which seems logical).
And I assume File.Copy does the same.

AFAIK there is no function that does it differently.

You could make a method that copies a file and restores some
of the file properties, e.g. by using File.Get/SetCreationTime.

Regards,

Luc Pattyn

[My Articles]

electriac5-May-07 8:16

5-May-07 8:16

Yeah! I am now using Western Digital drive mirroring but it is not convienent. Did a thirty day agricultral experiment that required date and time of each picture to be recorded. Did not realize that this data would be lost when the images were transfered from the chip to the hard drive. Lost thirty days work.

Guess Ile have to write a piece of software for this.

Luc Pattyn5-May-07 8:45

Re: Preserve creation date [modified]

5-May-07 8:45

Two ideas:

If the file is created and written only once (i.e. not modified afterwards) on a Windows
system, then the "last written" or "modification" date should not change when the file
gets copied by either Win Explorer or File.Copy

If your pictures are JPEG files generated by a camera, it is very likely they contain a lot
of "properties" including the date & time of exposure (assuming the camera's real-time clock
has been initialized correctly...).

Smile | :)

Luc Pattyn

[My Articles]

electriac5-May-07 9:01

5-May-07 9:01

Luc

Thanks the modified date is correct for all the pics. So I will be able to salvage my work. Some how modified does not seem to be good terminology for when a picture is taken but thats MS for ya. I still am going to write a copy utility for my own use. The code below seems to work. Any Suggestions.

<br />
private void button1_Click(object sender, EventArgs e)<br />
        {<br />
            string infile="";<br />
            string outfile = "C:\\test.jpg";<br />
            OpenFileDialog dlg = new OpenFileDialog();<br />
            if (dlg.ShowDialog() == DialogResult.OK)<br />
            {<br />
                infile = dlg.FileName;<br />
                File.Copy(infile, outfile, true);<br />
                File.SetCreationTime(outfile,File.GetCreationTime(infile));<br />
            } <br />
        }<br />

-- modified at 17:54 Saturday 5th May, 2007

Luc Pattyn5-May-07 9:20

5-May-07 9:20

Hi,

1. file times
creation time is when the file got created
modification time is when the file contents last have been modified
and yes that can be before creation time (when file gets copied, as you have experienced).

2. code comments
I would put infile declaration and all actions inside the OK? test

3. JPEG
as I said before, JPEG files typically contain a lot of properties, which may be the safest way
to retrieve exposure information. If you want to make sure for your files, just mail me one.

Regards

Luc Pattyn

[My Articles]

Luc Pattyn5-May-07 12:31

5-May-07 12:31

Hi,

digital cameras add a lot of information into the JPEG files they generate.

This info is loaded into the Image object when executing Image.FromFile(filespec).
The info can be interrogated, item by item, by calling Image.GetPropertyItem(itemID).

AFAIK the info is preserved (not updated) when such image gets operated upon;
So as long as you modify and then save the Image to another file, you will still have
all the original properties, which may have become invalid, since they contain size,
datetime, etc, which may have been modified or become meaningless by the applied modifications.

When you create a new image from an existing one, as in new Bitmap(myImage),
the properties are not copied.

BTW you can add or modify properties using Image.SetPropertyItem().

Regards,

Luc Pattyn

[My Articles]

electriac5-May-07 12:42

5-May-07 12:42

Luc your the best!

AFSEKI7-May-07 2:56

AFSEKI

7-May-07 2:56

Use:

File.GetCreationTime and store it in a file ( .xml, .txt, .dat...e.t.c )

Hope this helps...

electriac8-May-07 12:36