Overview

This chapter describes the 8-channel 1746-NR8 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-NR8 RTD/Resistance Input Module is

referred to as simply the 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.