Rockwell Automation 1790P-4R0 CompactBlock LDX I/O RTD/Resistance Input Module User Manual
Page 68
Publication 1790-UM002A-EN-P
G-2
effective resolution – The number of bits in a channel configuration
word that do not vary due to noise.
excitation current – A user-selectable current that the module sends
through the input device to produce an analog signal that the module can
process and convert to temperature (RTD) or resistance in ohms
(resistance device).
filter – A device that passes a signal or range of signals and eliminates all
others.
filter frequency – The user-selectable frequency for a digital filter.
full-scale – The magnitude of input over which normal operation is
permitted.
full-scale range – The difference between the maximum and minimum
specified analog input values for a device.
input data scaling – Data scaling that depends on the data format
selected for a channel configuration word. Scaling is selected to fit the
temperature or voltage resolution for your application.
input image – The input from the module to the controller. The input
image contains the module data words and status bits.
linearity error – Any deviation of the converted input or actual output
from a straight line of values representing the ideal analog input. An
analog input is composed of a series of input values corresponding to
digital codes. For an ideal analog input, the values lie in a straight line
spaced by inputs corresponding to 1 LSB. Linearity is expressed in percent
full-scale input. See the variation from the straight line due to linearity
error (exaggerated) in the example below.
LSB – Least significant bit. The LSB represents the smallest value within a
string of bits. For analog modules, 16-bit, two’s complement binary codes
are used in the I/O image. For analog inputs, the LSB is defined as the
rightmost bit of the 16-bit field (bit 0). The weight of the LSB value is
defined as the full-scale range divided by the resolution.
module scan time – same as module update time
Ideal Transfer
Actual Transfer
Function
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