WinCC v7.x/VBS - conversion DWORD to Single (float)

Dear Colleagues,

I have a problem converting 32-bit integer number to floating point value (32-bit) in WinCC VB Script editor.

What I need to do is to merge 4 bytes into 32-bit value and map it to Single data type to get floating point number. Conversion needs to be done to regular format of IEEE 754 (32-bit). I have found this:

https://msdn.microsoft.com/en-us/library/system.bitconverter.tosingle.aspx

but I'm not able to implement that method in WinCC VBS editor as this is problably dedicated for VB not VBS/VBA editors.

In C-script it is pretty easy task as I need just to point floating point area as follows:

BYTE b1, b2, b3, b4;

float tag_float;

tag_float = (float*)(b1<<24 | b2<<16 | b3<<8 | b4);

and this gives me floating point number out of 4 separate bytes.

Have any of You guys faced such issue and maybe hove solution for that task in VBS?

I have base VB script:

Dim b1, b2, b3, b4

Dim tag_float

tag_float = b1*16777216 + b2*65536 + b3*256 + b4 '????

but this obviously gives just an integer value of DWORD.

I would appreciate help in this seemingly easy matter.

Thanks in advance for any hints.

Best greets,

radek

Hello radekk,

in your VBS code you DIM b1, b2, b3, b4 and tag_float, but you do not assign a variable type.

Thus VBS will set the type of variable by first value written to it.

As b1 to b4 represent bytes, we are talking about values from 0 to 255 - which would be integer values.

And the constants you multiply the bytes with (256, 65536, .....) are also integers. Thus tag_float will be integer too.

Maybe it works if you change your conversion line to:

tag_float = b1*16777216.0 + b2*65536.0 + b3*256.0 + b4 

or

tag_float = b1*16777216 + b2*65536 + b3*256 + b4 + 0.123

tag_float = tag_float - 0.123

regards