Allen-Bradley ProcessLogix 1756-IA16, Справочное руководство, Страница: 56 / 120

Publication 1757-RM810A-EN-P - May 2002
3-16 Functional Blocks
Logic Blocks
2OO3 (2 out of 3 voting)
AND
Description 2-out-of-3 Voting block – outputs (DISCREP and MAJ) are determined as follows:
DISCREP = NOT (IN [1] = IN [2] = IN [3]) for duration >= DELAY
MAJ = value held by the majority of the inputs.
Function Sets the output (DISCREP) to ON if NOT all inputs agree for a specified time duration (DELAY); otherwise, it is set to
OFF.
Inputs IN [1..3] = Boolean values
Outputs DISCREP & MAJ = Boolean values
Parameters DELAYTIME
DISCREP EUDESC
HIALM IN [0..2]
MAJ ORDERINCM
Description Provides an up to 8-input AND algorithm, meaning that it performs the Boolean operation of conjunction. Each input
(IN [1]
,
IN [2], ..., IN [8]) has the capability of being optionally inverted, if required.
Function
Turns the Boolean value output (OUT) ON only when all inputs (IN [1]
,
IN [2], ..., IN [8]) are ON. Therefore:
•
If all inputs (IN [1..8]) are ON, then: OUT = ON.
•
If any input (IN [x]) is OFF, then: OUT = OFF.
If input is inverted, then:
•
Actual_IN [x] = NOT (IN [x])
•
Else, Actual_IN [x] = IN [x]
Where x equals any valid input.
Truth Table IN [1]
OFF
OFF
ON
ON IN [2]
OFF
ON
OFF
ON OUT
OFF
OFF
OFF
ON
Inputs IN [1..8] = Boolean value
Outputs OUT = Boolean value controlled by the status of the input signals.
Parameters IN [1..8]
INPTINVSTS [1..8] ORDERINCM
OUT