Re: Converting decimal to BCD (binary coded decimal)...

John Morley <jmorley@xxxxxxxxxxxxxxxxxxxxxx> wrote in news:ugxYLKbzFHA.3000
@TK2MSFTNGP12.phx.gbl:

> Hi All,
>
> Is there a handy way to convert a decimal value to it's equivalent BCD
> representation in VB?? I need to send some data to a controller that
> expects date data in BCD. For example the month of October (decimal 10)
> would be sent as "16" (BCD equivalent of 10).
>
> Thanks!
>
> John
>

Hi John,

I didn't even know that BCD was used like this, as I've only used it in
rotary switches. I'm not exactly sure why this would be used. Sending "10"
as a string would be 2 bytes, and BCD would be 1, but just straight binary
would be one also.

So the others know, here's an article:

http://www.danbbs.dk/~erikoest/bcd.htm

Specifically, your talking about packed-BCD. Each digit is represented by 4
bits of a byte.

As per your example, October, month 10, BCD=16.....

0000 0000 = 1 Byte
0001 = 1
0000 = 0

00010000 = 16 in BCD

I got this to work with some long code that had 3 functions, but while
looking at the output, and noticed a pattern.

Since one byte represents 2 digits, the following works on a 2 digit number
up to 99. That may be an easy limitation to work with.

CodeBegin
-----------------------------------------------------
Public Function BCDxx(decNum As Integer) As Integer

BCDxx = Int(decNum / 10) * 16
BCDxx = BCDxx + (decNum Mod 10)

End Function
-----------------------------------------------------
CodeEnd

That's what the pattern worked out to be, I can post the long code if
needed.

But, simple is almost always better.

Regards,

DanS
.

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