Rockwell Automation 1746-NI8 SLC 500 Analog Input Modules User Manual - Manual (Page 85)

Glossary G–2
Publication 1746Ć6.8 - April 1997
dB - (decibel) A logarithmic measure of the ratio of two signal
levels.
data word - A 16-bit integer that represents the value of the analog
input 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).
digital filter - A filter implemented in firmware, using discrete,
sampled data of the input signal.
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 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.
gain drift - The change in full scale transition voltage measured over
the operating temperature range of the module.
input data scaling -The data formats that you select to define the
logical increments of the channel data word. These may be
scaled-for-PID, or Engineering Units, which are automatically
scaled. They may also be proportional counts, which you must
calculate to fit the resolution of the quantity being measured in your
application.
input image - The input from the 1746-NI8 module to the SLC
processor. The input image contains the module data words and
status words.
local configuration - A control system where all the chassis are
located within several feet of the processor, and chassis-to-chassis
communication is via a 1746-C7 or 1746-C9 ribbon cable.
LSB - (Least Significant Bit) The bit that represents the smallest
value within a string of bits.
module scan time - same as module update time
module update time - The time required for the module to sample
and convert the input signals of all enabled input channels and make
the resulting data values available to the SLC
t processor.
multiplexer - An switching system that allows several input signals
to share a common A/D converter.