A compare function represents a data manipulation instruction. U90 Ladder uses function blocks to operate compare functions. Each function block takes 2 inputs (MI, SI or a constant integer) and manipulates them according to the function block instruction.
If the function block instructions are true (logic 1): power flows through the block.
If the function block instructions are false (logic 0): power does not flow through the block.
There are 6 types of Compare Functions: