LOG (Log Base 10) Ladder Logic Instruction

Definition

The Natural Log instruction is a ladder logic rung output instruction that takes the log base 10 of the Source value and places the result in the Destination tag. The instruction is enabled when the preceding logic is true and disabled otherwise. The values can be constants, tags or any combination.

The Source value should be greater than zero. If the Source value is not greater than zero the overflow status flag is set S:V. The result will be greater than or equal to -37.92978 and less than or equal to 38.53184.

List of possible arguments

SOURCE and DESTINATION can be any combination of the following data types.

  • CONSTANT             Can’t be the DESTINATION obviously
  • SINT              
  • INT
  • DINT
  • REAL

Note: Arithmetic status flags are affected (S:V, S:Z, S:N, S:C). Overflow, Zero, Negative, and Carry.