Allen-Bradley ProcessLogix 1756-IA16, Reference Manual, Page: 64 / 120

Publication 1757-RM810A-EN-P - May 2002
3-24 Functional Blocks
nOON (n out of N voting)
NOR
Description n-out-of-N voting block; outputs are computed as follows:
•
VOTED output is set to ON if at least n inputs are ON, otherwise it is set to OFF.
•
ORED output is set to ON if any input is ON, otherwise it is set to OFF.
•
ALARM output is a pulse output -- every time an input turns ON, a fixed pulse (of the pulsewidth specified by
PULSEWIDTH parameter) is generated, provided the total number of inputs which are ON is less than n.
Function Provides VOTED, ORED and ALARM outputs in support of logical functions.
Inputs IN [1..20] = Boolean value
n = 8-bit unsigned integer (range = 1-5)
There can be a maximum of 20 inputs (N = 20)
Outputs VOTED, ORED = Boolean state (ON or OFF) as determined by the inputs.
ALARM = pulse output, width specified by parameter PULSEWIDTH. PULSEWIDTH is a unit integer with time unit in
seconds
Parameters ALARM
IN [1..20]
N
ORDERINCM ORED
PULSEWIDTH
VOTED
Description Provides an up to 8-input NOR algorithm, meaning that it performs an inverted OR 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 if any one input (IN [1], IN [2], ..., IN [8]) is ON; therefore:
If all inputs are OFF, then: OUT = ON.
If any one input is ON, then: OUT = OFF.
Truth Table IN [1]
OFF
OFF
ON
ON IN [2]
OFF
ON
OFF
ON
Inputs IN [1..8] = Boolean values
Outputs OUT = Boolean value controlled by status of input signals
Parameters INPTINVSTS [1..8]