send & receive data from serialport1 line

Question

0.00/5 (No votes)

See more:

hi i need to connect via serial port to a micro controller. if i click on a button, it sends a packet of data to micro controller and if it receives this, sends back special data.
for ex., i send by press on button: "AA BB 80 01 FF 01 80"
that "AA BB" is start of frame, "01 80" CRC, and others are data
reply of this message from micro controller is: "BB AA 80 32 (some of data) (2 bytes CRC)"
that "BB AA" is start of frame, "2 bytes CRC" CRC, and others are data
all of these data are as hex code!

question1: when i press on button and send data to micro controller, and i wrote on button_click event

serialPort1.WriteLine("AA BB 01 FF 01 80");

. shall this data("AA BB 01 FF 01 80") change to hex? because micro controller just read hex!

question2: if this data received by micro controller and it replies data as "BB AA 80 32 (some of data) (2 bytes CRC)". but now, i need to use "some of data" that are in hex code, and display these on text box. what shall i do?

Posted 20-Oct-13 20:31pm

mohsenvasefi

Add a Solution

2 solutions

Solution 2

Quote:
shall this data("AA BB 01 FF 01 80") change to hex? because micro controller just read hex!

Probably (very probably, indeed) the microcontroller 'understands' binary data (hexadecimal is just a textual representation of numbers, that is, binary data).
As already suggested by Richard you have to write (and read) byte buffers, e.g.

C#

byte[] buf = { 0xAA, 0xBB, 0x80, 0x01, 0xFF, 0x01, 0x80 };
serialPort1.Write(buf, 0, buf.Length);

Posted 20-Oct-13 22:36pm

CPallini

Comments

mohsenvasefi 21-Oct-13 8:01am

did you mean write and readbyte function? by readbyte function, we can just read one byte synchronously, not more (for ex., 20bytes)

CPallini 21-Oct-13 14:14pm

Nope, I meant read/write byte buffers:
http://msdn.microsoft.com/en-us/library/ms143549(v=vs.110).aspx
http://msdn.microsoft.com/en-us/library/ms143551(v=vs.110).aspx

mohsenvasefi 22-Oct-13 1:30am

ok, thank you
but my project give back an error about using serialPort1.Read

byte[] buff={0};
serialPort1.Read(buff, 10, 10);

it's in "button_click" event, when i pressed on button, give back an error and display "Offset and length were out of bounds for the array or count is greater than the number of elements from index to the end of the source collection."
what does it mean?

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Richard MacCutchan · Accepted Answer · 2013-10-20T22:20:00

Solution 1

You probably should be using the SerialPort.Write[^] and SerialPort.Read[^] methods, to handle pure hex data. You can then convert the input bytes to string data to display in your text box.

Posted 20-Oct-13 22:20pm

Richard MacCutchan

Comments

CPallini 21-Oct-13 4:32am

5.

mohsenvasefi 21-Oct-13 4:34am

are you sure?
serialPort1.WriteLine("AABB8001FF0180");
serialPort1.ReadExisting();
string vtype = Convert.ToString(serialPort1.ReadLine());
is it true? can Convert.ToString convert hex to string fo display? and for display, shall i write on button_click event or text box change? which one?

Richard MacCutchan 21-Oct-13 4:56am

Your WriteLine call is not sending what you think. The character string "AABB8001FF0180", is actually 00410041004200420038003000300031004600460030003100380030 in hex. You need to start with byte[] buffers for both input and output and convert to printable caharacters where necessary.

mohsenvasefi 21-Oct-13 7:51am

he character string "AABB8001FF0180", is actually 00410041004200420038003000300031004600460030003100380030 in hex.

why did you write "0041" instead of "41" for "A"???

Richard MacCutchan 21-Oct-13 8:39am

OK, my mistake, serialPort uses ASCII encoding be default, so the actual hex bytes will be as above but without all the 00 prefix bytes.

mohsenvasefi 21-Oct-13 8:55am

ok. and how can i convert ASCII code of other byte to hex? it's main & important problem! how can i convert ASCII to hex? not watching to ASCII code table for conversion. it should be done automatically

Richard MacCutchan 21-Oct-13 9:03am

You need to write the code to convert each two characters to their hex value. The digits '0' to '9' just need the subtraction of '0' to give the hex value. The characters 'A' to 'F' are a little more involved: the formula is: character - 'A' + 10. Then shift the first value left by 4 bits and add the second value giving the final hex byte.

mohsenvasefi 21-Oct-13 9:41am

what? 4 bits shift to left and then?
for ex. for Z, 90-65+10=35
after 4 bits shift to left, 5 and then? how can add the second value? where is the second value?
or for F, 70-65+10=15
after 4 bits shift to left, 5???
it's wrong! hex code of "F" is 46!

Richard MacCutchan 21-Oct-13 12:04pm

What does Z have to do with this? Hex values are 0-9 and A-F, nothing further. To convert a string to hex:


byte[] asciiCharacters;
byte[] hexBytes;
// repeat from here ...
byte nextByte = asciiCharacters[i] - '0';
if (asciiCharacters[i] >= 'A' && asciiCharacters[i] <= 'F') // so it's 'A' thru 'F'
    nextByte = asciiCharacters[i] - 'A' + 10;
hexBytes[index] = nextByte << 4;
i++;
nextByte = asciiCharacters[i] - '0';
if (asciiCharacters[i] >= 'A' && asciiCharacters[i] <= 'F') // so it's 'A' thru 'F'
    nextByte = asciiCharacters[i] - 'A' + 10;
hexBytes[index] += nextByte;
i++;
index++;
// etc

mohsenvasefi 21-Oct-13 9:52am

i think below method is right (just for numbers and A~F letters):
for numbers: hex code=ASCII character-48+30;

for letters: byte n=(ASCII character/16);
byte m=(ASCII character%16); (% means remain of ASCII character to 16)
byte letter=(n<<4)+m; (n<<4 means shift to left)

Richard MacCutchan 21-Oct-13 12:05pm

No, see my reply above.

mohsenvasefi 21-Oct-13 12:12pm

Ok, good. i read your code.
but which line of my code is wrong? do you say the code about numbers is false?

Richard MacCutchan 22-Oct-13 2:30am

The whole thing is wrong, you are taking an ASCII character, doing some calculations and ending up with the same ASCII character.

mohsenvasefi 22-Oct-13 3:07am

could you write hex code for numbers with this method that you wrote? what does it work?
in byte nextByte = asciiCharacters[i] - '0'; '0' is in hex or ASCII? i think it should be in hex, because of byte[] nextByte

Richard MacCutchan 22-Oct-13 3:50am

I wrote it for you in the above code. You still do not seem to understand the difference between a character and its HEX representation. The character '0' is equivalent to the hex number x30, so the string "07" is x3037 in hex. So to convert that string to a real hex value to send to the microcontroller, we need to strip the base x30 from each character and concatenate them into the hex value x07, as in my code above. And, as shown, for the values 'A' to 'F' we need to subtract the base value of 'A' and add 10 to get the numbers 10 thru 15.

mohsenvasefi 22-Oct-13 3:58am

i understood your code, but want to know in nextByte calculation, '0' is equivalent of hex or ASCII!
ok, thanks

Richard MacCutchan 22-Oct-13 4:07am

Well let's look at what it is in the code: '0' is a character constant, which is 0 in ASCII or 30 in hex, 48 in decimal, 60 in octal, 110000 in binary, etc. You really need to go back to your computer basics to review how single bytes are held in memory and how they can be represented.

mohsenvasefi 22-Oct-13 4:13am

OK! thank you...