4.4 Flip-Flop types
4.4.1 [10] RS-Flip-Flop, Superior
Type Function Type Function
I1
b Set input
O1
b output O1
I2
b Reset input
O2
b
negated output O2 =
1O
I3
b Superior Set input
P1
I4
b Superior Reset input
P2
Description:
The inputs of the instruction are the assigned signal sources.
TRUE at the Set input sets the output to TRUE. TRUE at the Reset input sets the output to
FALSE. If FALSE is present on both inputs, the current status of the output signal is maintained.
TRUE at the Superior Set input sets the output to TRUE. TRUE at the Superior Reset input sets
the output to FALSE.
Priority:
Superior Reset (highest priority)
Superior Set
Reset
Set (lowest priority)
Via the output buffer, the output signal is globally available.
Inputs Superior Set and Superior Reset are connected in series with the function. Levels at Set
input I1 and Reset input I2 are processed internally. As soon as the Superior Set or Superior
Reset is reset, the output is switched to the internally saved value.
RS-Flip-Flop, Superior
S
R
SS
SR
O1
Q
State
x x X 1 0 Off (Superior)
X X 1 0 1 On (Superior)
0 0 0 0 Q
n-1
Hold
0 1 0 0 0 Reset
1 0 0 0 1 Set
1 1 0 0 0 Off
Set: TRUE at the S input sets the output to TRUE.
Save: If all inputs are FALSE, the output remains unchanged.
Reset: If R input is TRUE, the output is set to logic FALSE.
Off: If both inputs are set to TRUE, the output is FALSE.
Superior-Set: SS, set output to TRUE.
Superior-Reset: SR, set output to FALSE (CLR).
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