LEFT

FunctionA function calculates a result according to the current value of its inputs. A function has no internal data and is not linked to declared instances. - Extract characters of a string on the left.

Inputs

IN : STRING   Character string
NBC : DINT    Number of characters to extract

Outputs

Q : STRING    String containing the first NBC characters of IN.

Remarks

In FFLD language, the operation is executed only if the input rung (EN) is TRUE. The output rung (ENO) keeps the same value as the input rung.

In IL"Instruction list" This is a low-level language and resembles assembly, the first input (the string) must be loaded in the current result before calling the function. The second argument is the operand of the function.

ST Language

Q := LEFT (IN, NBC);

FBD Language

FFLD Language

(* The function is executed only if EN is TRUE *)
(* ENO keeps the same value as EN *)

IL Language:

Op1: 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     IN
     LEFT   NBC
     ST     Q

See also

+   MLEN   DELETE   INSERT   FIND   REPLACE    RIGHT   MID