Allen-Bradley LOGIX 5000 User Manual

Chapter 7
Equipment Phase Instructions
458 Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
Structured Text
None
Enter the parentheses ( ) after the instruction mnemonic, even though there are no
operands.
Guidelines for using the PPD Instruction
Guideline Details
Organize logic as a series of steps. PPD instructions (breakpoints) are easiest to use if the logic moves through
defined steps, such as a state machine or SFC.
• A breakpoint only signals that specific conditions are met. It does
not stop the execution of the equipment phase.
• To have logic actually break (pause) at a breakpoint, organize the logic
so that it stays at the step at which the breakpoint occurred until it
receives the resume command.
Do not use a PPD instruction as a temporary
end of the routine.
Even when an equipment phase pauses, it continues to execute all its logic.
• When a PPD instruction executes, it only sets the Paused bit for the
equipment phase.
• If programing the PPD instruction in RLL, it disables only the rest of the
logic on its rung. It does not terminate or suspend the execution of the
routine.
• Think of the PPD instruction as a condition that applies or is ignored
based on the auto pause and pause commands.
Use PPD instruction to pause at the same
breakpoint over several scans.
When the PauseEnabled bit is TRUE, an equipment phase goes to Paused at
the first PPD instruction whose conditions are true. If the PPD instruction
executes over several scans, the equipment phase may continually pause at
the same breakpoint.
Make sure only 1 PPD instruction at a time is
true.
A PPD instruction does not have a control tag to remember whether it
executed.
• Anytime its conditions are true (and the equipment phase is in a
substate with PauseEnabled True), the PPD instruction acts as a
breakpoint (and pauses the phase by disabling the rest of the logic on
the rung).
• Limiting logic to one possible breakpoint at a time ensures a pause at
the required breakpoint.
Choose the substate to use. PPD instructions (breakpoints) work only when the equipment phase
PauseEnabled bit is True.
To pause at: Give this command:
Each true breakpoint Auto Pause
First true breakpoint Pause
Affects Math Status Flags
No

Allen-Bradley LOGIX 5000 Specifications

General

Brand	Allen-Bradley
Model	LOGIX 5000
Category	Controller
Language	English