Rockwell Automation 1746-NR8 SLC 500 RTD/Resistance Input Module User Manual - Manual (Page 11)

1 Publication 1746-UM003A-EN-P
Chapter
1
Overview
This chapter describes the 8-channel 1746-NR8 RTD/Resistance Input 1746-NR8 RTD/Resistance Input 1746-NR8 RTD/Resistance Input 1746-NR8 RTD/Resistance Input
Module Module Module 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-NR8 RTD/Resistance Input Module 1746-NR8 RTD/Resistance Input Module 1746-NR8 RTD/Resistance Input Module 1746-NR8 RTD/Resistance Input Module is
referred to as simply the RTD module RTD module RTD module RTD module.
The RTD module receives and stores digitally converted analog data from
RTDs or other resistance inputs such as potentiometers into its image table for
retrieval by all fixed and modular SLC 500 processors. An RTD consists of a
temperature-sensing element connected by 2, 3, or 4 wires that provide input
to the RTD module. The module supports connections from any combination
of up to eight RTDs of various types (for example: platinum, nickel, copper, or
nickel-iron) or other resistance inputs.
Description The RTD module supplies a small current to each RTD connected to the
module inputs (up to 8 input channels). The module provides on-board
scaling and converts RTD 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 the subsection
entitled System Overview
System Overview System Overview System Overview later in this chapter.