Say, in the WinCC Comfort Panel there is an array of bytes read (which originally was LReal) from a device (let it be S7-300 CPU).

Is it possible to convert it into an internal LReal tag in the panel?

TIAP 13 SP 2

Den dobry,

maybe idea, with C script? I don't know exactly...

Dzień dobry

Well, I've found only VB script-like thing which is very limited comparing to the MS original. So after few quick trials with Uncle Google support I gave up and decide to ask here for solution.

I tried as follows: array of bytes with Hex() -> hex string with CDbl() -> LReal.

Unfortunately CDbl treats hex string as a Long.

Some problems needs time to solve themself.

As "normal" way seems not possible (i.e. casting to Double = LReal) I tried hard way. Not fully finnished and thought over but maybe someone will find it as a good start point.

This scripts takes a little-endian array of bytes myBytes tag and writes the result to myLReal tag. 

Dim myDouble, expotent, isNormal, isNaN, index, sign

'casting biased expotent as integer to Double
expotent = CDbl(myBytes(6) And &HF0)/2^4 + CDbl(myBytes(7) And &H7F)*2^4

'special cases checks
'is normal
If expotent <> 0 Then isNormal = 1 End If
'is NaN?
If expotent = CDbl(&H7FF) Then isNaN = True End If
'is + or -
If (myBytes(7) And &H80) <> 0 Then
sign = -1
Else
sign = 1
End If

'remove bias from expotent
expotent = expotent - 1023

myDouble = 0
'cast fraction as integer to Double and extend it to full significand
For index = 0 To 5
myDouble = myDouble + CDbl(myBytes(index))*2^(8*index)
Next
myDouble = myDouble + CDbl(myBytes(6) And &H0F)*2^(8*index) + isNormal*2^52

'_assembling_ a Double from the parts
'number is normal or subnormal but not NaN nor inf
If myDouble <> 0 And isNaN = False Then
myDouble = myDouble*2^(expotent - 52)*sign
'is zero (signed)
ElseIf myDouble = 0 And isNormal = 0 Then
myDouble = 0.0 * sign
'is +/- inf
ElseIf isNaN = True And myDouble = 0 Then
myDouble = 0.0
Err.Raise 6 'overflow
'NaN
Else
myDouble = 0.0
'no idea what to do...
End If

myLReal = myDouble

I'd forget... The code was tested only on a simulator.