Mitsubishi Electric WS0-CPU0 - JK Flip-Flop

Chapter 9
133
Logic programming – Function blocks
Truth table for the RS Flip-Flop function block
The following applies for the truth table in this section:
 “0” means logic Low.
 “1” means logic High.
 “n–1” references the preceding value.
 “n” references the current value.
 “x” means “any” = “0” or “1”.
Set Reset Output Q
n–1
Output Q
n
Output /Q
n
0 0 0 0 1
0 0 1 1 0
0 1 x 0 1
1 0 x 1 0
1 1 x 0 1
9.7.8 JK Flip-Flop
Function block diagram
General description
The JK Flip-Flop function block has three inputs. The J input and K input have only
an effect on the outputs when a rising edge is detected at the Clock input. In this
case …
 If J input is High and K input is Low, the Q output will be High and the /Q (= Q
inverted) output will be Low.
 If J input is Low and K input is High, the Q output will be Low and the /Q output will
be High.
 If both inputs are Low, the last values of outputs Q and /Q will be held.
 If both inputs are High, the outputs will toggle, i.e. their last values will be inverted.
Parameters of the function block
Parameter Possible values
Number of outputs
 1 (Q)
 2 (Q and /Q)
Invert J input Each input of this function block can be inverted (see Section 9.5.2).
Invert Clock input
Invert K input
Table 34:
Truth table for the RS Flip-
Flop function block
Figure 106:
Function block diagram for
the JK Flip-Flop function
block
Table 35:
Parameters of the JK Flip-
Flop function block