Rockwell-automation 1769-OF4VI Compact I/O Isolated Analog Modules User Manual download pdf (Page 119)

1 Publication 1769-UM014B-EN-P - May 2010

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-OF4VI Compact I/O Isolated Analog Modules User Manual Page 119