Allen-Bradley ProcessLogix 1756-IA16, Справочное руководство, Страница: 58 / 120

Publication 1757-RM810A-EN-P - May 2002
3-18 Functional Blocks
FTRIG (Falling-edge Trigger)
GE (Greater than or Equal to)
Description Falling-edge Trigger Block -- sets the output (OUT) to ON following the ON-to-OFF transition of the input and stays ON
until the next execution cycle, at which time it returns to OFF.
Function Provides falling edge change detection, thereby turning the output ON if an ON-to-OFF transition is detected.
Inputs IN = Boolean value
Outputs OUT = Boolean value
Parameters IN
ORDERINCM OUT
Description Provides a 2-input Compare Greater Than or Equal (with deadband) function, meaning it checks to see if one
designated input (IN [1]) is greater than or equal to either a second input (IN [2]) or, for single input, a designated trip
point parameter.
Function Turns the digital output (OUT) ON only when one designated input (IN [1]) is greater 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] - DEADBAND) < IN [1] < IN [2], 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