Allen-Bradley ProcessLogix 1756-IA16, Reference Manual, Page: 63 / 120

Publication 1757-RM810A-EN-P - May 2002
Functional Blocks 3-23
NAND
NE (Not Equal)
Description Provides an up to 8-input NAND algorithm, meaning that it performs an inverted AND function. Each input (IN [1], IN
[2], ..., IN [8]) has the capability of being optionally inverted, if required.
Function Turns the digital output (OUT) OFF only when all inputs (IN [1], IN [2], ..., IN [8]) are ON; therefore:
•
If all inputs are ON, then: OUT = OFF.
•
If any input is OFF, then: OUT = ON.
Truth Table IN [1]
OFF
OFF
ON
ON IN [2]
OFF
ON
OFF
ON
Inputs IN [1], IN [2], ..., IN [8] = digital signals
Outputs OUT = digital signal controlled by status of the input signals.
Parameters IN [1..8]
INPTINVSTS [1..8]
Description Provides a 2-input Compare Not Equal (with deadband range) function, meaning that it checks to see if one
designated input (IN [1]) is not equal to either a second input (IN [2]) or, for single input, a designated trip point
parameter (TP).
Function Turns the digital output (OUT) ON only when the two inputs (IN [1] and IN [2]) are not considered equal within a
specified deadband range.
If ABS (IN [1] -IN [2]) <= DEADBAND1, then: OUT = OFF.
Else, if ABS (IN [1] -IN [2]) > DEADBAND2, then: OUT = ON.
If IN [1] and/or IN [2] are NaN (Not a Number), OUT is not changed.
DEADBAND1 and DEADBAND2 must satisfy the following constraint: 0<= DEADBAND1 <= DEADBAND2.
DEADBAND1, DEADBAND2, and TP = real numbers.
Inputs IN [1] and IN [2] = real numbers
If there is only one input, then IN [2] = TP.
Outputs OUT = Boolean value.
Comparison blocks should set their outputs to Off if any of the inputs are NaN. This “fail safe” behavior is consistent
with the IEEE 754 floating point standard.
Parameters DEADBAND1
DEADBAND2
IN [0..2]
NUMOFINPUTS ORDERINCM
OUT
TP
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