Allen-Bradley ProcessLogix 1757 Series User Manual

Publication 1757-RM810A-EN-P - May 2002
Functional Blocks 3-19
GT (Greater Than)
LE (Less than or Equal to)
Description Provides a 1- or 2-input Compare Greater Than (with deadband) function, meaning that it checks to see if one
designated input (IN [1]) is greater than 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 one designated input (IN [1]) is greater than a second input (IN [2]) or, for
single input, a designated trip point parameter (TP) as follows:
• If IN [1] > IN [2], then: OUT = ON.
• If IN [1] <= (IN [2] - DEADBAND), then: OUT = OFF.
• If (IN [2] - DEADBAND) < IN [1] <= IN [2], then: OUT is not changed.
Inputs IN [1..2] = Real numbers
If only one input connection is configured, an input port is displayed for parameter TP and the value of TP is used
instead of IN [2].
If IN [1] and/or IN [2]are NaN (Not a Number), OUT is not changed.
DEADBAND and TP have the same data type as that of the inputs.
Outputs OUT = Boolean value controlled by the status of the input signals.
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 DEADBAND
IN [0..2]
NUMOFINPUTS
ORDERINCM
OUT
TP
Description Provides a 2-input Compare Less Than or Equal (with deadband) function, meaning it checks to see if one designated
input (IN [1]) is less than or 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 one designated input (IN [1]) is less than or equal to a second input (IN
[2]) or, for single input, a designated trip point parameter (TP) as follows:
• If IN [1] <= IN [2], then: OUT = ON.
• If IN [1] > (IN [2] + DEADBAND), then: OUT = OFF.
• If IN [2] < IN [1] <= (IN [2] + DEADBAND), then: output is not changed.
Inputs IN [1..2] = Real numbers
If only one input connection is configured, an input port is displayed for parameter TP and the value of TP is used
instead of IN [2].
If IN [1] and/or IN [2] are NaN (Not a Number), OUT is not changed.
DEADBAND and TP have the same data type as that of the inputs.
Outputs OUT = Boolean value controlled by the status of the input signals.
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 DEADBAND
IN [0..2]
NUMOFINPUTS
ORDERINCM
OUT
TP
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Allen-Bradley ProcessLogix 1757 Series Specifications

General

Brand	Allen-Bradley
Model	ProcessLogix 1757 Series
Category	Control Unit
Language	English