Rockwell Automation 1769-OF4 Compact Analog Output Module - Manual (Page 67)

Publication 1769-UM020A-EN-P - December 2009 67
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
.
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.
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 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.
configuration word – Contains the channel configuration
information needed by the module to configure and operate each
channel.
D/A converter – Refers to the digital-to-analog converter inherent to
the module. The converter produces an analog DC voltage or current
signal whose instantaneous magnitude is proportional to the
magnitude of a digital value.
dB – (decibel) A logarithmic measure of the ratio of two signal levels.
data echo – The digital value currently being converted by the D/A
converter and shown in words 1…4 of the module’s input data file.
Under normal operating conditions, the data echo value is the same
value that is being sent from the bus master to the output module.
data word – A 16-bit integer that represents the value of the analog
output channel. The channel data word is valid only when the
channel is enabled and there are no channel errors. When the channel
is disabled the channel data word is cleared (0).
differential operation – The difference in voltage between a
channel’s positive terminal and negative terminal.
full scale – The magnitude of voltage or current over which normal
operation is permitted.
full scale error – (gain error) The difference in slope between the
actual and ideal analog transfer functions.