Rockwell Automation 1746-NT8 SLC 500 Thermocouple/mV Analog Input Module User Manual - Manual (Page 103)

1 Publication 1746-UM022B-EN-P - January 2005
Glossary
You should understand the following terms and abbreviations before
using this guide.
A/D
Refers to analog-to-digital conversion. The conversion produces a
digital value whose magnitude is proportional to the instantaneous
magnitude of an analog input signal.
Attenuation
The reduction in magnitude of a signal as it passes through a system.
The opposite of gain.
Channel
Refers to one of eight, small-signal analog input interfaces to the
modules’ terminal block. Each channel is configured for connection to
a thermocouple or DC millivolt (mV) input device, and has its own
configuration and status words.
Chassis
A hardware assembly that houses devices such as I/O modules,
adapter modules, processor modules, and power supplies.
CJC
(Cold-Junction Compensation) The means by which the module
compensates for the offset voltage error introduced by the
temperature at the junction between the thermocouple lead wire and
the input terminal block (the cold junction).
Common mode rejection ratio (CMRR)
The ratio of a device’s differential voltage gain to common mode
voltage gain. Expressed in dB, CMRR is a comparative measure of a
device’s ability to reject interference caused by a voltage common to
its terminal relative to ground.
Common mode voltage
The voltage difference between the negative terminal and analog
common during normal differential operation.