Rockwell-automation 1769-IF4FXOF2F Compact Combination Fast Analog I/O Manual de usuario descargar pdf (Pagina 85)

Publication 1769-UM019A-EN-P - October 2008 85

Glossary

The following terms and abbreviations are used throughout this

manual. For definitions of terms not listed here refer to the

Allen-Bradley Industrial Automation Glossary, publication AG-7.1

A/D converter– Refers to the analog to digital converter inherent to

the module. The converter produces a digital value whose magnitude

is proportional to the magnitude of an analog input signal.

alternate last state – A configuration selection that instructs the

module to convert a user-specified value from the channel fault or

program/idle word to the output value when the module enters the

Fault or Program mode.

analog input module – A module that contains circuits that convert

analog voltage or current input signals to digital values that can be

manipulated by the controller.

attenuation – The reduction in the magnitude of a signal as it passes

through a system.

bus connector – A 16-pin male and female connector that provides

electrical interconnection between the modules.

channel – Refers to analog input or output interfaces available on the

module’s terminal block. Each channel is configured for connection to

a variable voltage or current input or output device, and has its own

data and diagnostic status words.

channel update time – The time required for the module to sample

and convert the input signals of one enabled input channel and

update the channel data word.

common mode rejection – For analog inputs, the maximum level to

which a common mode input voltage appears in the numerical value

read by the controller, expressed in dB.

common mode rejection ratio – The ratio of a device’s differential

voltage gain to common mode voltage gain. Expressed in dB, CMRR is

a comparative measure of a device’s ability to reject interference

caused by a voltage common to its input terminals relative to ground.

CMRR=20 Log

10 (V1/V2)

common mode voltage – For analog inputs, the voltage difference

between the negative terminal and analog common during normal

differential operation.

common mode voltage range – For analog inputs, the largest

voltage difference allowed between either the positive or negative

terminal and analog common during normal differential operation.

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Rockwell-automation 1769-IF4FXOF2F Compact Combination Fast Analog I/O Manual de usuario Pagina 85