Rockwell Automation 1771-IR , D17716.5.76 RTD INPUT MODULE - Manual (Page 9)

Chapter 2
2
Chapter
2Ć1
Overview of the RTD Input Module
This chapter gives you information on:
features of the input module
how an input module communicates with programmable controllers
The RTD input module is an intelligent block transfer module that interfaces
analog input signals with any Allen–Bradley programmable controllers that
have block transfer capability. Block transfer programming moves input data
words from the module’s memory to a designated area in the processor data
table in a single scan. It also moves configuration words from the processor data
table to module memory.
The input module is a single slot module and requires no external power supply.
After scanning the analog inputs, the input data is converted to a specified data
type in a digital format to be transferred to the processor’s data table on request.
The block transfer mode is disabled until this input scan is complete.
Consequently, the minimum interval between block transfer reads (50ms) is the
same as the total input update time for each analog input module.
The RTD input module senses up to 6 RTD signals at its inputs and converts
them to corresponding temperature or resistance in 4–digit BCD or 16–bit
binary format.
Module features include:
Six resistance temperature detector inputs
Reports
o C, o F, or ohms for 100 ohm platinum or 10 ohm copper sensors
Reports ohms for other types of sensors
software
configurable
0.1 degree/10 milliohm input resolution
auto–calibration
open wire detection
The module can be configured for 100 ohm platinum or 10 ohm copper RTDs,
or other sensor types such as 120 ohm nickel RTDs. Temperature ranges are
available in degrees C or F. Values can also be measured in ohms.
When using 10 ohm copper RTDs, it is necessary to dedicate your module for
exclusive use with 10 ohm copper RTDs. You can configure the module to
accept signals from any combination of 100 ohm platinum and other types of
non–copper RTDs. Both cases are determined by block transfer write (BTW)
selection.
Chapter Objectives
Module Description
Features of the Input Module