Detach from Phase (PDET)
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.
After a program executes a PDET instruction, the program
no longer
owns the equipment phase. This frees the equipment phase for ownership by another program or by FactoryTalk Batch
software. Use the PDET instruction only if the program previously took ownership of an equipment phase via an Attach to Equipment Phase (PATT) instruction.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.
Ladder Diagram
Function Block
This instruction is not available in function block.
Structured Text
PDET(Phase_Name);
Operands
Ladder Diagram
Operand | Type | Format | Description |
|---|---|---|---|
Phase Name | PHASE | Name of the equipment phase | Equipment phase no longer to own. |
Structured Text
The operands are the same as those for the Ladder Diagram PDET instruction.
Affects Math Status Flags
No
Major/Minor Faults
None. See
Index Through Arrays
for operand-related faults.Execution
For Structured Text, EnableIn is always true during normal scan. Therefore, if the instruction is in the control path activated by the logic, it will execute.
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
If
Step.6
= 1 (step 6 in the sequence) thenEach PDET instruction relinquishes ownership of the phases that the sequence owned.
Each
Ownership
bit = 0. (In the Ownership
tag, each equipment phase is assigned a bit.)Done
= 1. (This signals the sequence to go to the next step.)
Structured Text
When the sequence executes, the Relinquish_Ownership action:
- Relinquishes ownership of the equipment phase.
- Clears the ownership flags (bits that the SFC set when it took ownership of the equipment phases).
Using an action Qualifier of type P1 limits the action execution to the first scan of that step.
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