Rockwell Automation 1746-NT4 Series B,D17466.6.1 SLC 500 4-Channel Thermocouple/mV Input Module User Manual User Manual
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Publication 1746-UM007C-EN-P - July 2004
Glossary 2
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 low-pass noise filter incorporated into the A/D
converter. The digital filter provides a very steep roll-off above its
cut-off frequency, which provides high frequency noise rejection.
effective resolution - The number of bits in the channel data word
that do not vary due to noise.
filter frequency - The user-selectable first-notch frequency for the
A/D converter’s digital filter. The digital filter provides high noise
rejection at this frequency.
full scale error (gain error) - The difference in slope between the
actual and ideal analog/thermocouple transfer functions.
full scale range (FSR) - The difference between the maximum and
minimum specified analog/thermocouple 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 for millivolt, thermocouple, or
CJC inputs, which are automatically scaled. They may also be
proportional counts, which you must calculate to fit your application’s
temperature or voltage resolution.
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) - Refers to a data increment defined as the
full scale range divided by the resolution. The bit that represents the
smallest value within a string of bits.
multiplexer - An switching system that allows several input signals to
share a common A/D converter.
normal mode rejection (differential mode rejection) - A logarithmic
measure in dB, of a device’s ability to reject noise signals between or
among circuit signal conductors, but not between equipment
grounding conductor or signal reference structure and the signal
conductors.