CMP

Function BlockA function block groups an algorithm and a set of private data. It has inputs and outputs. - Comparison with detailed outputs for integer inputs

Inputs

IN1 : DINT  First value
IN2 : DINT  Second value

Outputs

LT : BOOL  TRUE if IN1 < IN2
EQ : BOOL  TRUE if IN1 = IN2
GT : BOOL  TRUE if IN1 > IN2

Remarks

In FFLD language, the rung input (EN) validates the operation. The rung output is the result of "LT" (lower than) comparison).

ST Language

(* MyCmp is declared as an instance of CMP function block *)
MyCMP (IN1, IN2);
bLT := MyCmp.LT;
bEQ := MyCmp.EQ;
bGT := MyCmp.GT;

FBD Language

FFLD Language

(* the comparison is performed only if EN is TRUE   *)

IL Language:

(* MyCmp is declared as an instance of CMP function block *)
Op1: CAL MyCmp (IN1, IN2)
     LD"Ladder diagram" Ladder logic is a method of drawing electrical logic schematics. It is now a very popular graphical language for programming Programmable Logic Controllers (PLCs). It was originally invented to describe logic made from relays. The name is based on the observation that programs in this language resemble ladders, with two vertical "rails" and a series of horizontal "rungs" between them  MyCmp.LT
     ST  bLT
     LD  MyCmp.EQ
     ST  bEQ
     LD  MyCmp.GT
     ST  bGT

See also

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