Introduction

Labels serve as destinations for jumps.

Jumps and labels in ST are a supplement to the IEC 61131-3 and must be enabled explicitly.

Label Properties

Label properties:

  • Labels must always be the first element in a line.

  • Labels may only come before instructions of the first order (not in loops).

  • The name must be clear throughout the directory, and it is not upper/lower case sensitive.

  • Labels must conform to the general naming conventions.

  • Labels are separated by a colon : from the following instruction.

Properties of Jumps

Properties of jumps

  • Jumps can be made within program and DFB sections.

  • Jumps are only possible in the current section.

Example

IF var1 THEN
   JMP START;
:
:START: ...