Comments by Member 11423970 (Top 46 by date)

I know how to use System.Drawing.Graphics to draw an image in the main form, but I don't know how to do it in a tabpage. I don't know the the code line to refer to that specific object. Can you put me an example or a link to a page that talks about that?

Thanks for replyng. I'm quite new with programming so forgive my lack of vocabulary.

I have created two typepages in the main form using the designer ("System.Windows.Forms.TabPage1" and "System.Windows.Forms.TabPage2") and I want to change de background image of both of then. I searched throw the net how to add a background image to the main form, and I guess that to do the same with the tabpages I have to use the Onpaint method, but I don't know how and I find nothing in the net.

No, there are no timers.

I more or less solve the problem closing the serial port after doing the first taks and opening it again to continue with the readTo task. Is not probably the best solution but is quite straightforward.

If you can think in other explanation or solution, it would be more than welcome.

Thank you very much for replying anyway.

Yes, I tried with all the Reading methods, but it gets stack in that line. I had some problems programing in datareceived thread, thats why I finally did it this way.

What is funny is that when I don't use the Botonclick method, it Works perfectly, but if I used it to give priority to another task, it Works great until the 'readTo' line.

Sorry guys. I wasn't available. So you are telling me to implement you solutions where exatcly? I tried them in my main form and in my main form designer and still not working, so I'm probably doing something wrong with your solutions.

Ok, thak you very much for all the help

Very complete answer and very helpful resources. I have read them and I will work with them. I general, you are suggesting me to créate an Async Method?

Yes, I'm a beginner with programming, so forget me if I don't get all of your answer. No loops to wait, got it. The input_data ends with an special character that doesnt' appear on this screen, so the idea is taht, read all the input data and when the symbol appears says, this is all my string of information, and send the next code to recieved another piece of data.

I don't know if there is any command that allows me to wait until the serial port sends all the data before sending the second code.

That's it!!! Thank you very much for your help, it Works perfectly. Thanks!

I upload the new code. I change char array for a byte array but I still have a different answer.

Then I don't know what I'm doing wrong with my verification program. I wrote this main program, and my result is not the same:

Sorry again for bothering. I translate the code to C#, but aparently is wrong in some point, because the result is 0x913C instead of 0x313C. I cannot manage to see where is the error.

Better said, I didn't find it, is the one of the webpage you suggested me. I've been analysing it and I think that mine does the same, but I am not sure.

I've found this other algorythm of Xmodem, but I am not sure if is the same as mine as is writen in C. Maybe I am missing something.

int calcrc(ptr, count)
char *ptr;
int count;
{
int crc, i;

crc = 0;
while (--count >= 0) {
crc = crc ^ (int)*ptr++ << 8;
for (i = 0; i < 8; ++i)
if (crc & 0x8000)
crc = crc << 1 ^ 0x1021;
else
crc = crc << 1;
}
return (crc & 0xFFFF);
}

I checked both, but nothing that can solve my problema appears :(

I am almost sure that the problema is in the algorythm. I initialise the values to 0x0000 and 1021 which are the ones used for Xmodem CITT but there must be something with the bit order I am using.

I read in this webpage some reversing process but I don't understand it very well: http://tiku.io/questions/599184/crc16-checksum-hcs08-vs-kermit-vs-xmodem

I tried using the polynom, but I still have an incorrect CRC. I read the C code example and I think that the algorythm is ok, so I don't know where is the problem. I feel that this is getting very close, but I'm not able to find why I can calculate the CRC-16 and CRC Kermit numbers and not the Crc-Citt Xmodem number.

It should be simple to generate the Xmodem number but I don't know why is becoming so hard.

Ok, I'll try that then.

Thank you very much.

I think I don't understand it correctly. I am writing a program where I write a number and it calculates the CRC Xmodem number of 4 caracters. I don't need to send it anywhere or recieved acknowledment. The programe I am trying to write is similar to the one on this page: http://www.lammertbies.nl/comm/info/crc-calculation.html

I am using a Byte array of 4096 bytes, is not that suppossed to be enough?

I am very sorry, I have spent so many hours with this program that already I don't know what I am uploading.

And believe me that I am not just "copying" code. I read all the answers, the good ones and your conplains, but most of the time you people just send me to other web pages, in where I read the same information again and again, and even if I a read it carefully, I can get to finished the program.

I'm sure that for you is a silly program, and that you can't came up with the problem right away, but for me is quite hard. Probably you think that I am a noob and all the things that you usually say to people you think inferior to you and that I should be doing a different thing in order to programming.

I check a lot of algorythms to take out the CRC number, most of them say different thing, or that is my perception, and I tried a lot of them, I wrote a lot of them myself taking into account other programmers ideas and comments and none of them worked.

Mr. OriginalGriff, you can be tired of me and remove my questions, but do not insult me saying that I am doing nothing and that I am taking advantage of your work and the one of the rest of the programmers.

You mean that I need to change just the algorythm part or that the whole program needs to be changed?

After checking both pages, I still don't get where is the problem.

http://www.lammertbies.nl/comm/info/crc-calculation.html

I hava tried both, to mask and to unchecked. With both I avoid now the overflow, but the result I get it isn't the same as the one in http://www.lammertbies.nl/comm/info/crc-calculation.html web page.

Ok, thanks a million for the answer and the lesson.

As I am using them as a public enum I declared them as int, but still not working

I tried that before, Crc16Ccitt CRC = new Crc16Ccitt(InitialCrcValue.Zeros); , which is the one I am actually looking for, but the builder tells me that InitialCrcValue and Zeros do not exist, and I do not know which declaration type are.

In my main program I am defining the Class and trying to use it, but I do not know whats wrong in the definition of the class.

Crc16Ccitt CRC = new Crc16Ccitt();

string myCRC = CRC.ComputeChecksumBytes(number).ToString();

Here is my main program. I just need to try the CRC class that I found and créate a CRC Xmodem calculator to use it in a project

I need to write a main program in where I can write a number, and the class shown above returns me the CRC XModem of that number.

I don't get it very well. I know it is something to do with ushort, but I don't know how to do the masking.

Happens the same. I just create an array of 256 because at the beggining was of 16, and I thought that was the cause of the overflow, but after changing, the problem persisted.

Yes, I debugged it. The problem is in the 'for'. When it starts the second loop, it overflows:

for (int j = 0; j < len; j++)
{
i = ( crc >> 12 ) ^ ( data[j] >> 4 );
crc = (ushort) (crc_table[ i & 0x0F ] ^ ( crc << 4 ));
i = ( crc >> 12 ) ^ ( data[j] >> 0 );
crc = (ushort) (crc_table[ i & 0x0F ] ^ ( crc << 4 ));
}