JK Flip-Flop (JKFF)
The JKFF instruction complements the Q and QNot outputs when the Clock input transitions
from cleared to set.
When Clear is set, the instructions clears Q and sets QNot. Otherwise, if Clock is set
and Clockn-1 is cleared, the instruction toggles Q and QNot.
The instruction sets Clockn-1 = Clock state every scan.
Available Languages
Ladder Diagram
This instruction is not available in ladder diagram logic.
Structured Text
JKFF(JKFF_tag);
Operands
FLIP_FLOP_JK Structure
Input Parameter | Data Type | Description |
|---|---|---|
EnableIn | BOOL | Enable input. If cleared, the instruction does not execute and
outputs are not updated. Default is set. |
Clear | BOOL | Clear input to the instruction. If set, the instruction clears Q and sets QNot. |
Clock | BOOL | Clock input to the instruction. Default is cleared. |
Output Parameter | Data Type | Description |
|---|---|---|
EnableOut | BOOL | Indicates if instruction is enabled. |
Q | BOOL | The output of the instruction. |
QNot | BOOL | The complement of the Q output. |
Structured Text
Operand | Type | Format | Description |
|---|---|---|---|
JKFF tag | FLIP_FLOP_JK | Structure | JKFF structure |
See Structured Text syntax for more information on the syntax of
expressions within structured text.
Affects Math Status Flags
No
Major/Minor Faults
None specific to this instruction. See Common Attributes for operand-related faults.
Execution
Structured Text
Condition/State | Action Taken |
|---|---|
Prescan | EnableIn and EnableOut bits are cleared to false. |
Normal Execution | EnableIn and EnableOut bits are set to true. The instruction executes. |
Postscan | EnableIn and EnableOut bits are cleared to false. |
Examples
When Clock goes from cleared to set, the JKFF instruction toggles Q. If Clear is set, Q
is always cleared. The JKFF instruction sets QNot to the opposite state of Q.
Structured Text
JKFF_01.Clear := clear_input;
JKFF_01.Clock := clock_input;
JKFF(JKFF_01);
q_output := JKFF_01.Q;
qNot_output := JKFF_01.QNot;
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