Allen-Bradley ProcessLogix 1756-IA16, Reference Manual, Page: 68 / 120

Publication 1757-RM810A-EN-P - May 2002
3-28 Functional Blocks
RS (Reset dominant SR-FLIP-FLOP)
RTRIG (Rising edge Trigger)
SEL (Binary Selection)
Description Provides a bistable Reset Dominant flip-flop as defined in the IEC DIS 1131-3 standard.
Function Specifies the output (Q) of the flip-flop as a function of the input S (Set), the input R (Reset), and the last state of Q.
Truth Table S
0 (OFF)
0 (OFF)
1 (ON)
1 (ON) R
0 (OFF)
1 (ON)
0 (OFF)
1 (ON) Q
No Change
0 (OFF)
1 (ON)
0 (OFF)
Inputs S and R = Boolean value
Outputs Q = Boolean value controlled by the status of the input signals.
Parameters ORDERINCM
Q R
S
Description Rising-edge Trigger sets the output (OUT) to ON following the OFF-to-ON transition of the input (IN) and stays at ON
until the next execution cycle, at which time it returns to OFF.
Function Provides rising edge change detection, thereby turning the output ON if an OFF-to-ON transition is detected.
Inputs IN = Boolean value
Outputs OUT = Boolean value
Parameters IN
ORDERINCM OUT
Description Provides a 3-input selector function, meaning it selects 1 of 2 inputs (IN [1] or IN [2]) depending on the separate
input G.
Function Sets the actual output (OUT) equal to the value of 1 of 2 inputs (IN [1] or IN [2]), depending on the value of a separate
input (G).
Truth Table IN [1]
IN [1]
IN [1] IN [2]
IN [2]
IN [2] G
OFF
ON OUT
IN [1]
IN [2]
Inputs IN [1..2] =Boolean value
G = Boolean value
Outputs OUT =Boolean value depending on the values of IN [1] and IN [2].
Parameters G
IN [0..2]