Siemens PLC programming I_DI, DI_R, DIV_R, CTCH, MUL_R, ROUND

I_DI, integer (INT) to double integer (DINT)
DI_R, double integer (DINT) to floating point number (real number REAL)
DIV_R, floating point number (REAL) division
CTCH, this instruction was not found;
MUL_R, floating point number (REAL) multiplication
ROUND, floating point number (REAL) rounded to double integer (DINT)
I, INT, (single) integer;
DI, ie DINT, double integer;
R, ie REAL, floating point number;
Generally there are four operators (add ADD, subtract SUB, multiply MUL, except DIV) and add “_I”, which is to operate on integers; add “_DI”, which is to calculate double integers; add “_R”, which is floating The number of points is calculated.