AutoGen_6484613

I need to convert a real data item, for example, 75.80, to a word. I want to send it to a VW variable. I know I can do this by converting it to DINT, but I lose the decimals.

You wish to fit a REAL number into a 16-bit variable. The S7-200 does not have a native data type that is a 16-bit floating number (https://en.wikipedia.org/wiki/Half-precision_floating-point_format).

But it may be helpful if you could explain a bit more as to what you want to do. I will take some guessing.

(a) DISPLAY
Assume the variable needs to be displayed. Generate an INT value that includes 2 decimals by scaling. Multiply with 100. The display needs to show the decimal point in the correct position. (Siemens HMIs can do this easily but some other brands is difficult.)

value    := 75.80

tempReal := value * 100.0

tempDint := Real-to-Dint(tempReal)

output   := Dint-to-Int(tempDint)

Keep in mind that the DINT variable has x2 16-bit words. VD200 is composed of VW200 and VW202. If the number is small enough: VD200 equals VW200. 

(b) COMMUNICATION
Some communication protocols handles only words. A REAL can be transmitted via its WORD components.