Read hex value from RS-232 ??

[Gagan_01]

Hi,

I sending data from my PIC to the COM1 serial port and have labview read that using the VISA Read. I can correctly read the hex value and display is using a string indicator, but how do i use this hex value in futher calculations ? I am unable to convert is to a decimal number, i tried to use the hexadecimal string to decimal number function but it wont work. Are there any solutions ??

Thank you
Gagan

[tbob]

When you say the hexidecimal string to number function don't work, exactly what do you mean? Does the number come out wrong? Once a string is converted into a number, the computer stores and handles the number in binary format, a series of ones and zeros. Please be more clear on your problem or post an example.

[Gagan_01]

Hi,

After using the Hexadecimal String to Decimal number function when i try to display the number on an indicator all i see is 0. But the string indicator shows the correct value (when displayed in HEX).All i want to do is use the recieved data to make some futher numeric calculations, is there any way to do this ?

Thanks

[pawel]

There is a function "hexadecimal string to number" under the functions->strings->string/number conversion palete. The number this function returns is the numerical representation of your string. See enclosed file.

hope it helps
Pawel

[Gagan_01]

Hi,

I have attached the VI that i am trying to execute, to be more clear the string indicator shows the correct value of the displayed recieved byte in hex. But the numeric indicator shows a 0 ??

Thanks

[Donald]

Depending on the number of bytes and the endian nature of what you're getting, direct use of the Typecast primitive (Advanced>Data Manipulation palette) will work by itself or with a little help moving bytes using Split Number and Join Number primitives (same palette):

There have been a few recent posts on the topic with several example VIs.

http://forums.ni.com/ni/board/message?board.id=170&message.id=105851&query.id=0
http://forums.ni.com/ni/board/message?board.id=170&message.id=104302&query.id=0#M104302
http://forums.ni.com/ni/board/message?board.id=170&message.id=105158#M105158

The "whatever String to Number" functions translate strings of ascii code into the corresponding number, (e.g. a 4 byte string "FFFF" (0x 4646 4646) into a U32 with a value of 65535, etc.)

[Dennis_Knutson]

When you can only see the hex when turning on hex display of the string, you can't use the string conversion Hexidecimal to Number. You can use either String to Byte Array or a type cast. See the attached picture.

[tbob]

Your string indicator is set for hex display. What you will see here is the ASCII code of the characters being received by RS232, not the actual characters. Change your indicator to Normal display and you will see the actual string being received. Since the numeric value you are seeing is 0, I suspect the string being received is not a valid hex number.

[Gagan_01]

Hi,

Thanks for your response. If i send hex value 0xff what i see in the string as hex is ff. So i am getting the exact hex value but i still unable to use it as a numeric value for calculations ??

Thanks
Gagan

[dirtyb15]

I would also recomend trying the type cast function.