# Converting ASCII to Hex error

Hi

My program opens up the comm port and receives data from another computer. The ascii text received i convert to hex by

strHex = Hex(Asc(character))

but it doesnt convert correctly.

If the other computer sent 01 in hex I will receive 01 in hex, if they send FF in hex I receive 7F in hex

If we take this down to binary
FF = 11111111
7F = 01111111

The conversion from ascii to a number seems to take away the first bit

this is the same with many other hex values with a beginning 1 at the front taken away

The error comes at the point of converting the character to an ascii number

82 hex = 130 dec

but i get 02 dec

again it removed the beginning bit.

my comm port settings are
baud = 19200 (yes the same as the other computer)
comm = 1
parity = none
databit = 8
stopbit = 1

i have tried most other values of my comm settings but only the ones listed above gives the closest hex values back

anyone have any ideas

I use the rs232 class (the one microsoft gives you) for serial port communication

thanks
LVL 4
###### Who is Participating?

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Commented:
Try this routine:

It expects a long.  If you are receiving a string, you can convert it like this:

Dim long as Int64 = convert.ToInt64(YourDataAsString)

' Convert from decimal to hexadecimal
' if you pass the Digits argument, the result is truncated to that number of
' digits
'
' you should always specify Digits if passing negative values

Function Hex(ByVal value As Long, Optional ByVal digits As Short = -1) As String
' convert to base-16
Dim res As String = Convert.ToString(value, 16).ToUpper()

' truncate or extend the number
If digits > 0 Then
If digits < res.Length Then
' truncate the result
res = res.Substring(res.Length - digits)
ElseIf digits > res.Length Then
' we must extend the result to the left
If value >= 0 Then
' extend with zeroes if positive
Else
' extend with "F"s if negative
End If
End If
End If
Return res
End Function

Jeff
0

Experts Exchange Solution brought to you by

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Author Commented:
Sorry, nope didn't work

there is a possibility that the ascii characters coming into my program could be stripped of their beginning 1.
0
Author Commented:
OK

I found a solution. Just another stupid microsoft stuff up once again. I found a serial port comm program built in vb .net that reads all the information back perfectly.

And when reading through the revisions of this class i found

'  Rev.4 (24/05/2002)
'  Fixed problem with ASCII Encoding truncating 8th bit

here are the details for the class
'===================================================
'
'      Module                        :      Rs232
'      Description            :      Class for handling RS232 comunication with VB.Net
'      Created                        :      10/08/2001 - 8:45:25
'      WebSite                        :      www.codeworks.it/net/index.htm
'===================================================

I have seen vb .net 2005 and they are creating a serial port namespace although in beta 1 its not complete yet, so hopefully next year, serial comms will be much better than now.

0
###### It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Visual Basic.NET

From novice to tech pro — start learning today.