Rockwell Automation 1769-IT6 Compact I/O 1769-IT6 Thermocouple/mV Input Module User Manual
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Rockwell Automation Publication 1769-UM004B-EN-P - March 2010
Glossary
dB
(decibel) A logarithmic measure of the ratio of two signal levels.
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.
effective resolution
The number of bits in a channel configuration word that do not vary due to
noise.
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.
gain drift
Change in full-scale transition voltage measured over the operating temperature
range of the module.
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