Rockwell Automation 1746-NR4 SLC 500 RTD/Resistance Input Module/ Instructions - Manual (Page 3)

SLC 500™ RTD/Resistance Input Module 3
Publication 1746-IN012B-EN-P - May 2001
Overview
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
four RTDs of various types (for example: platinum, nickel, copper, or nickel-iron)
or other resistance inputs. See the input specifications beginning on page 20 for
RTD types, their associated temperature ranges, and the analog input signal ranges
that each 1746-NR4 channel will support. 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 four 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 3. 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.