Rockwell Automation 1746-NR4 SLC RTD/Resistance Input Module User Manual - Manual (Page 11)

11 Publication 1746-UM008B-EN-P - December 2006
Chapter
1
Overview
This chapter describes the four-channel 1746-NR4 RTD/Resistance
Input Module and explains how the SLC controller gathers RTD
(Resistance Temperature Detector) temperature or resistance-initiated
analog input from the module. Included is:
• a general description of the module’s hardware and software
features.
• an overview of system operation.
For the rest of the manual, the 1746-NR4 RTD/Resistance Input
Module is referred to as simply the RTD module.
Description The RTD module receives and stores digitally converted analog data
from RTD units or other resistance inputs such as potentiometers into
its image table for retrieval by all fixed and modular SLC 500
processors. An RTD module consists of a temperature-sensing element
connected by two, three, or four wires that provide input to the RTD
module. The module supports connections from any combination of
up to four RTD units of various types (for example: platinum, nickel,
copper, or nickel-iron) or other resistance inputs.
The RTD module supplies a small current to each RTD unit connected
to the module inputs (up to 4 input channels). The module provides
on-board scaling and converts RTD unit input to temperature (°C, °F)
or reports resistance input in ohms.
Each input channel is individually configurable for a specific input
device. Broken sensor detection (open- or short-circuit) is provided
for each input channel. In addition, the module provides indication if
the input signal is out-of-range.
For more detail on module functionality refer to System Overview
page 18.