Rockwell Automation 1746-NR8 SLC 500 RTD/Resistance Input Module/ Instructions - Manual (Page 5)

SLC 500™ RTD/Resistance Input Module 5
Publication 1746-IN007C-EN-P - December 2002
Overview
The RTD (Resistance Temperature Detector) 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. See the input specifications
beginning on page 19 for RTD types, their associated temperature ranges, and the
analog input signal ranges that each 1746-NR8 channel supports. 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.
The module contains a removable terminal block providing connection for any mix
of eight RTD sensors or resistance input devices. There are no output channels on
the module. Module configuration is done via the user program. There are no DIP
switches.
Channel Status LEDs
Channel status LEDs indicate the status for channels 0 through 7. Related error
information is contained in the channel status word. This includes conditions such
as:
•
normal operation
•
channel-related configuration errors
•
open-circuit errors
•
out-of-range errors
All channel errors are recoverable errors.
Module Status LED
The module status LED shows diagnostic or operating errors related to the module.
These non-recoverable errors may be detected during power-up or during
operation. Once an error has been detected, the module no longer communicates
with the SLC processor. Channel states are disabled and data words are cleared (0).
Failure of any diagnostic test results in a non-recoverable error and requires the
assistance of your local distributor or Rockwell Automation.