Chapter 4. Ladder Diagram (LD) ProgrammingGFK-2950C February 2018 634.1.1 Exponential/Logarithmic FunctionsWhen an exponential or logarithmic function receives power flow, it performs the appropriateoperation on the REAL or LREAL input value(s) and places the result in output Q.The inverse natural log (EXP)function raises e to the powerspecified by IN.The Power of X (EXPT) functionraises the value of input IN1 tothe power specified by the valueIN2.The Base 10 Logarithm (LOG)function calculates the base 10logarithm of IN.The Natural Logarithm (LN)function calculates the logarithmof IN.The power flow output is energized when the function is performed, unless Overflow or one of thefollowing invalid conditions occurs:■ IN < 0, for LOG or LN■ IN1 < 0, for EXPT■ IN is negative infinity, for EXP■ IN, IN1, or IN2 is a NaN (Not a Number)Operands of the Exponential/Logarithmic FunctionsParameter Description Allowed Operands OptionalIN or IN1 For EXP, LOG, and LN, IN contains the REAL or LREAL valueto be operated on.The EXPT function has two inputs, IN1 and IN2. For EXPT,IN1 is the base value and IN2 is the exponent.All except variableslocated in %S—%SCNoIN2 (EXPT) The REAL or LREAL exponent for EXPT. All except variableslocated in %S—%SCNoQ Contains the REAL or LREAL logarithmic/exponential valueof IN or of IN1 and IN2.All except constants andvariables located in%S—%SCNo
