Phase Clear Failure (PCLF)

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.
Use the PCLF instruction to clear the failure code of an equipment phase.
The PCLF instruction clears the failure code for an equipment phase.
  • Use only a PCLF instruction to clear the failure code of an equipment phase.
  • A CLR instruction, MOV instruction, or assignment (:=)
    does not
     change the failure code of an equipment phase.
Make sure the equipment phase
does not
 have other owners when using the PCLF instruction. The PCLF instruction
will not
 clear the failure code if
Logix Designer
, HMI,
FactoryTalk Batch
 software, or another program owns the equipment phase.
  • High priority HMI ownership is specific only to the
    CompactLogix
     5370 and
    ControlLogix
     5570 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.
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.
Available Languages
Ladder Diagram
PCLF_LD_avail_v31
Function Block
This instruction is not available in function block.
Structured Text
PCLF(Phase_Name);
Operands
Ladder Diagram
Operand
Type
Format
Description
Phase Name
PHASE
Name of the equipment phase
Equipment phase whose failure code to clear.
Structured Text
The operands are the same as those for the Ladder Diagram PCLF instruction.
Affects Math Status Flags
No
Major/Minor Faults
None. See
Index Through Arrays
 below 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 executes.
Condition/State
Action Taken
Prescan
No action taken.
Postscan
No action taken.
EnableIn is false
No action taken.
EnableIn is true
The instruction executes as described above.
Example
Ladder Diagram
If
Drain_Tank_Restart
 = 1 (restart the
Drain_Tank
 equipment phase) then
Clear the failure code of the
Drain_Tank
 equipment phase
Change the state of the
Drain_Tank
 equipment phase to restarting via the restart command.
Drain_Tank_Restart
 = 0;
PCLF_LD_ex_v31
Structured Text
(*If
Drain_Tank_Restart
 = on, then
Clear the failure code for the
Drain_Tank
 equipment phase.
Restart the
Drain_Tank
 equipment phase.
Turn off
Drain_Tank_Restart
.*)
If
Drain_Tank_Restart
 Then
PCLF(
Drain_Tank
);
PCMD(
Drain_Tank
,Restart,0);
Drain_Tank_Restart
 := 0;
End_If;
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