left

 Function A 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

Input	Data Type	Range	Unit	Default	Description
IN	STRING				Character string.
NBC	DINT				Number of characters to extract.

Outputs

Output	Data Type	Range	Unit	Description
Q	STRING			String containing the first NBC characters of IN.

Remarks

None

FBD Language Example

FFLD Language Example

• In the FFLD "Free Form Ladder Diagram" 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.
  • The function is executed only if EN is TRUE.
  • ENO keeps the same value as EN.

IL Language Example

• In the IL "Instruction List" This is a low-level language and resembles assembly Language, 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.

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

ST Language Example

Q := LEFT (IN, NBC);

See Also

• Addition +
• delete
• find
• insert
• mid
• mlen
• replace
• right