SIS function blocks > SIS Math Blocks > Logic Solver Calculation function block > Expressions in DeltaV SIS Software > Functions in Logic Solver Expressions

LOG2 function

Log base y of x. LOG2(x,y) returns the logarithm base y (operand two) of x (operand one) when successful. If x or y is not positive, LOG2 returns a zero value and BAD status.

Syntax:

'external reference' := LOG2(Real value, Real Value);

Example: 

VAR
   T63; T64; T17; (* Temporary values *)
END_VAR;
T63 := 0.5;
T64 := 15.803;
T17 := LOG2(T63, T64);

The above example shows T63 set to the value of 0.5 and T64 set to the value of 15.803. T17 is set to the result of LOG2(T63,T64), which is -3.982123.