Immediate Type Instructions

Immediate type motion instructions execute to completion in one scan.  If the controller detects an error during the execution of these instructions, the error status bit sets and the operation ends.
Examples of immediate type instructions include the:
  • Motion Change Dynamics (MCD) instruction
  • Motion Group Strobe Position (MGSP) instruction
Immediate instructions work as follows:
  1. When the rung that contains the motion instruction becomes true, the controller:
    • Sets the enable (EN) bit.
    • Clears the done (DN) bit.
    • Clears the error (ER) bit.
  2. The controller executes the instruction completely.
    If the controller:
    Then:
    Does not detect an error when the instruction executes
    The controller sets the .DN bit.
    Detects an error when the instruction executes
    The controller sets the .ER bit and stores an error code in the control structure.
  3. The next time the rung becomes false after either the .DN or .ER bit sets, the controller clears the .EN bit.
  4. The controller can execute the instruction again when the rung becomes true.
Provide Feedback
Have questions or feedback about this documentation? Please submit your feedback here.