Phase Paused (PPD)

This instruction applies to the Compact GuardLogix 5370 and Compact GuardLogix 5380, CompactLogix 5370, CompactLogix 5380, and CompactLogix 5480, ControlLogix 5570 and ControlLogix 5580, and GuardLogix 5570 and GuardLogix 5580 controllers.

TIP:

When using this instruction with ControlLogix redundancy system, outputs controlled by this instruction may not be bumpless during redundancy switchover, if the instruction and phase program are not scheduled in the highest priority task.

Use the PPD instruction to set up breakpoints within the logic of an equipment phase.

Pausing an equipment phase requires configuring break points by coding a PPD instruction in a phase's state routine logic. The phase state routine pauses when the PPD instruction executes and the phase receives a command to pause at its next opportunity.

This is a transitional instruction. Follow these steps when using it:

In ladder logic, insert an instruction to toggle the rung-condition-in from false to true each time the instruction should execute.

In a Structured Text routine, insert a condition for the instruction to cause it to execute only on a transition.

Three operator commands relate to the pause functionality:

Pause
: The Pause command enables or disables pausing execution of the phase when the next PPD instruction executes. The Pause command toggles the PauseEnabled bit ON (1) or OFF (0).

AutoPause:
The AutoPause command enables or disables automatically enabling pausing the phase after processing a Resume command. The AutoPause command toggles the AutoPauseEnabled bit ON (1) or OFF (0).

Resume:
The Resume command directs the firmware to resume executing the phase state routine logic. Resume sets the PauseEnabled and Paused bits OFF (0).

The Pause substate uses these three bits:

PauseEnabled
: The PauseEnabled bit maintains the status of processing a Pause command. This is bit 0 of the Pause substate.

When Paused is ON (1), execution of a PPD instruction pauses execution of the state routine's logic. This bit updates when it receives a Pause command (toggling the bit's value). Additionally, a Resume command sets PauseEnabled OFF (0), if the AutoPauseEnabled bit is ON (1).

AutoPauseEnabled
: The AutoPauseEnabled bit maintains the status of automatically enabling pausing immediately after a Resume command. This is bit 2 of the Pause substate.

This bit updates when it receives an AutoPause command (toggling the bit's value). When AutoPauseEnabled is ON (1) and the phase is Paused, the Resume command leaves PauseEnabled ON (1).

Paused
: The Paused bit maintains the pause-state of the phase, Paused (1) or not-Paused (0). This is bit 1 of the Pause substate. The Paused bit also disables the rest of the rung (RLL), it does not terminate or suspend the execution of the routine.

This bit is only set by the phase's firmware. When the PauseEnabled bit is ON, execution of a PPD instruction causes the Paused bit to be set to Paused (1) and firmware pauses execution of the phase state routine suspends. A Resume command sets the Paused bit to not-Paused (0) and the phase executes its logic.

Available Languages

Ladder Diagram

Function Block

This instruction is not available in function block.

Structured Text

PPD( );

Operands

Ladder Diagram

None

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

Major/Minor Faults

A major fault occurs if:	Fault type	Fault code
Instruction is called from outside an Equipment Phase program.	4	91

If an Add-On Instruction uses a PPD instruction, and a non-equipment phase program calls the Add-On Instruction,

Logix Designer

gives a warning. Check the Add-On Instruction for this instruction to disallow it. See Index Through Arrays
for operand-related faults.

Execution

Condition/State	Action Taken
Prescan	No action taken.
Postscan	No action taken.
EnableIn is false	No action taken.
EnableIn is true	The instruction executes.

Example

Ladder Diagram

Equipment Phase Instructions

Provide Feedback

Have questions or feedback about this documentation? Please submit your feedback here.