Rockwell Automation 1769-IF4FXOF2F Compact Combination Fast Analog I/O Module - Manual (Page 86)

86 Publication 1769-UM019A-EN-P - October 2008
Glossary
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 8 and 9 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
input or 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.
digital filter – A low-pass filter incorporated into the A/D converter.
The digital filter provides very steep roll-off above it’s cut-off
frequency, which provides high frequency noise rejection.
filter – A device that passes a signal or range of signals and eliminates
all others.
filter frequency – (-3 dB frequency) The user-selectable frequency.
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.
full scale range – (FSR) The difference between the maximum and
minimum specified analog input values.
hold last state – A configuration selection that instructs the module to
keep the outputs at the last converted value prior to the condition that
caused the control system to enter the Fault or Program mode.
input image – The input from the module to the controller. The input
image contains the module data words and status bits.