Conversion from an integral number type to another number type:
When you perform a type conversion from a larger to a smaller type, you risk losing some information. If the number you are converting exceeds the range limit, the first bytes for the number will be ignored.
Example in ST:
si := INT_TO_SINT(4223); (* Result is 127 *)
If you save the integer 4223 (16#107f represented hexadecimally) as a SINT variable, it will appear as 127 (16#7f represented hexadecimally).
Example in FBD:
