SLC 500
RTD/Resistance
Input Module
1746-NR4
User Manual
Important User Information
Solid state equipment has operational characteristics differing from those of
electromechanical equipment. Safety Guidelines for the Application,
Installation and Maintenance of Solid State Controls (publication SGI-1.1
available from your local Rockwell Automation sales office or online at
http://literature.rockwellautomation.com
) describes some important
differences between solid state equipment and hard-wired electromechanical
devices. Because of this difference, and also because of the wide variety of
uses for solid state equipment, all persons responsible for applying this
equipment must satisfy themselves that each intended application of this
equipment is acceptable.
In no event will Rockwell Automation, Inc. be responsible or liable for
indirect or consequential damages resulting from the use or application of
this equipment.
The examples and diagrams in this manual are included solely for illustrative
purposes. Because of the many variables and requirements associated with
any particular installation, Rockwell Automation, Inc. cannot assume
responsibility or liability for actual use based on the examples and diagrams.
No patent liability is assumed by Rockwell Automation, Inc. with respect to
use of information, circuits, equipment, or software described in this manual.
Reproduction of the contents of this manual, in whole or in part, without
written permission of Rockwell Automation, Inc., is prohibited.
Throughout this manual, when necessary, we use notes to make you aware
of safety considerations.
WARNING
Identifies information about practices or circumstances that can cause
an explosion in a hazardous environment, which may lead to personal
injury or death, property damage, or economic loss.
IMPORTANT
ATTENTION
Identifies information that is critical for successful application and
understanding of the product.
Identifies information about practices or circumstances that can lead
to personal injury or death, property damage, or economic loss.
Attentions help you identify a hazard, avoid a hazard, and recognize
the consequence
SHOCK HAZARD
Labels may be on or inside the equipment, for example, a drive or
motor, to alert people that dangerous voltage may be present.
BURN HAZARD
Labels may be on or inside the equipment, for example, a drive or
motor, to alert people that surfaces may be dangerous temperatures.
Rockwell Automation, Allen-Bradley, TechConnect, ControlLogix, RSLogix 500, and RSLinx are trademarks of Rockwell
Automation, Inc.
Trademarks not belonging to Rockwell Automation are property of their respective companies.
Summary of Changes
New Information
The information below summarizes the changes to this manual since
the last revision.
The table below lists sections that document new features and
additional information about existing features and shows where to
find this new information.
Change Page
Moved terms and abbreviations from
Preface to Glossary.
Updated programming examples to show
RSLogix 500 software.
Updated programming examples. Chapter 6
Updated programming examples. Chapter 8
Added Appendix D, I/O configuration. Appendix D, page 131
Preface
Throughout manual
3 Publication 1746-UM008B-EN-P - December 2006
4 Summary of Changes
Notes:
Publication 1746-UM008B-EN-P - December 2006
Overview
Quick Start Guide
Install and Wire the Module
Table of Contents
Preface
Use This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Who Should Use This Manual . . . . . . . . . . . . . . . . . . . . . . . . 7
Purpose of This Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Common Techniques Used in This Manual. . . . . . . . . . . . . . . 9
Chapter 1
Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Chapter 2
Required Tools and Equipment . . . . . . . . . . . . . . . . . . . . . 23
Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Chapter 3
EMC Directive. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Electrostatic Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
NR4 Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Module Location in Chassis . . . . . . . . . . . . . . . . . . . . . . . . . 35
Module Installation and Removal . . . . . . . . . . . . . . . . . . . . . 38
Terminal Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Preliminary Operating
Considerations
Channel Configuration, Data, and
Status
Chapter 4
Module ID Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Module Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Channel Filter Frequency Selection . . . . . . . . . . . . . . . . . . . 54
Scanning Process and Channel Timing . . . . . . . . . . . . . . . . . 58
Channel Turn-on, Turn-off, and Reconfiguration Time . . . . . 61
Response to Slot Disabling . . . . . . . . . . . . . . . . . . . . . . . . . 61
Chapter 5
Channel Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Channel Configuration Procedure . . . . . . . . . . . . . . . . . . . . 64
Channel Data Word. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Channel Status Checking . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
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6 Table of Contents
Ladder Programming Examples
Module Diagnostics and
Troubleshooting
Chapter 6
Device Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Initial Programming. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Dynamic Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Verify Channel Configuration Changes. . . . . . . . . . . . . . . . . 92
Interface to the PID Instruction . . . . . . . . . . . . . . . . . . . . . . 93
Use the Proportional Counts Data Format with
User-set Scaling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Monitor Channel Status Bits. . . . . . . . . . . . . . . . . . . . . . . . . 96
Invoke Autocalibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Chapter 7
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Module Operation vs. Channel Operation . . . . . . . . . . . . . . 99
Power Turn-on Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . 100
Channel Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
LED Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Replacement Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Contact Rockwell Automation . . . . . . . . . . . . . . . . . . . . . . 106
Application Examples
Specifications
RTD Standards
Configuration Worksheet
for RTD/Resistance Module
I/O Configuration
Chapter 8
Basic Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Supplementary Example . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Appendix A
Module Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Appendix B
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Appendix C
Channel Configuration Procedure . . . . . . . . . . . . . . . . . . . 125
Appendix D
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Glossary
Index
Publication 1746-UM008B-EN-P - December 2006
Preface
Use This Manual
Who Should Use This Manual
Read this preface to familiarize yourself with the rest of the manual.
This preface covers the following topics:
• Who should use this manual
• Purpose of this manual
• Terms and abbreviations
• Conventions used in this manual
• Allen-Bradley support
Use this manual if you are responsible for designing, installing,
programming, or troubleshooting control systems that use
Allen-Bradley small logic controllers.
You should have a basic understanding of SLC 500 products. You
should understand programmable controllers and be able to interpret
the ladder logic instructions required to control your application. If
you do not, contact your local Allen-Bradley representative for
information on available training courses before using this product.
Purpose of This Manual
This manual is a reference guide for the 1746-NR4 RTD/Resistance
Input Module. The manual:
• gives you an overview of system operation.
• explains the procedures you need to install and wire the module
at the application site.
• provides ladder programming examples.
• provides an application example of how this input module can
be used to control a process.
7 Publication 1746-UM008B-EN-P - December 2006
8 Preface
Contents of this Manual
Chapter Title Contents
Preface Describes the purpose, background, and
scope of this manual. Also specifies the
audience for whom this manual is intended
and defines key terms and abbreviations used
throughout this book.
1 Overview Provides a hardware and system overview.
Explains and illustrates the theory behind the
RTD input module.
2 Quick Start Guide Provides a general procedural roadmap to
help you get started using the RTD module.
3 Install and Wire Provides installation procedures and wiring
guidelines.
4 Preliminary Operating
Considerations
5 Channel Configuration,
Data, and Status
6 Ladder Programming
Examples
7 Module Diagnostics and
Troubleshooting
8 Application Examples Examines both basic and supplementary
Appendix A Specifications Provides physical, electrical, environmental,
Appendix B RTD Standards Provides physical, electrical, environmental,
Appendix C Configuration Worksheet
for RTD/Resistance Module
Appendix D I/O Configuration Contains information on the I/O configuration
Gives you the background information you
need to understand how to address and
configure the module for optimum operation
as well as how to make changes once the
module is in a run state.
Examines the channel configuration word and
the channel status word bit by bit, and
explains how the module uses configuration
data and generates status during operation.
Gives an example of the ladder logic required
to define the channel for operation. Also
includes representative examples for unique
programming requirements such as PID.
Explains how to interpret and correct
problems with your RTD module.
applications and gives examples of the ladder
programming necessary to achieve the
desired result.
and functional specifications for the RTD
module.
and functional specifications for the RTD and
potentiometer.
Provides a worksheet to help you configure
the module for operation.
procedure for RSLogix 500 Version 6.0 and
later software.
Publication 1746-UM008B-EN-P - December 2006
Preface 9
Additional Resources
The following documents contain additional information on Rockwell
Automation products.
For Read This Document Document
Number
An overview of the SLC 500 family of products SLC 500 Systems Selection Guide 1747-SG001
A description on how to install and use your modular SLC 500
programmable controller
A description on how to install and use your fixed SLC 500
programmable controller
A reference manual that contains status file data, instruction set,
and troubleshooting information.
A resource manual and user’s guide containing information about
the analog modules used in your SLC 500 system.
In-depth information on grounding and wiring Allen-Bradley
programmable controllers
A description of important differences between solid-state
programmable controller products and hard-wired
electromechanical devices
A glossary of industrial automation terms and abbreviations Allen–Bradley Industrial Automation Glossary AG-QR071
An article on wire sizes and types for grounding electrical
equipment
SLC 500 Module Hardware Style User Manual 1747-UM011
Installation & Operation Manual for Fixed
Hardware Style Programmable Controllers
SLC 500 Instruction Set Reference Manual 1747-RM001
SLC 500 4-Channel Analog I/O Modules User’s
Manual
Industrial Automation Wiring and Grounding
Guidelines
Application Considerations for Solid-State
Controls
National Electrical Code Published by the
1747-UM009
1746-UM005
1770-IN041
SGI-IN001
National Fire
Protection
Association of
Boston, MA
Common Techniques Used in This Manual
The following conventions are used throughout this manual:
• Bulleted lists such as this one provide information, not
procedural steps.
• Numbered lists provide sequential steps or hierarchical
information.
• Text in this font indicates words or phrases you should type.
Publication 1746-UM008B-EN-P - December 2006
10 Preface
Notes:
Publication 1746-UM008B-EN-P - December 2006
Chapter
1
Overview
This chapter describes the four-channel 1746-NR4 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-NR4 RTD/Resistance Input
Module is referred to as simply the RTD module.
Description
The RTD module receives and stores digitally converted analog data
from RTD units or other resistance inputs such as potentiometers into
its image table for retrieval by all fixed and modular SLC 500
processors. An RTD module consists of a temperature-sensing element
connected by two, three, or four wires that provide input to the RTD
module. The module supports connections from any combination of
up to four RTD units of various types (for example: platinum, nickel,
copper, or nickel-iron) or other resistance inputs.
The RTD module supplies a small current to each RTD unit connected
to the module inputs (up to 4 input channels). The module provides
on-board scaling and converts RTD unit 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 System Overview
page 18.
11 Publication 1746-UM008B-EN-P - December 2006
12 Overview
RT D
Simplified RTD Module Circuit
I
C= 0.5 or 2 mA
Constant Current Source
RTD Module
RT D
RT D
RT D
Sense
0
Return
Backplane
RT D
Sense
A/D
1
Return
Conversion
Digital Data
µP Circuit
Digital Data
RT D
Sense
2
Return
RT D
Sense
RT D
3
Return
Publication 1746-UM008B-EN-P - December 2006
RTD Compatibility
The following table lists the RTD types you can use with the RTD
module and gives each type’s associated temperature range,
resolution, and repeatability specifications.
RTD Unit Temperature Ranges, Resolution and Repeatability
Overview 13
RTD Unit Type Temperature Range
(0.5 mA excitation)
100 Ω -200…850 °C
(-328…1562 °F)
200 Ω -200…850 °C
Platinum (385)
(2)
500 Ω -200…850 °C
(-328…1562 °F)
(-328…1562 °F)
1000 Ω -200…850 °C
(-328…1562 °F)
100 Ω -200…630 °C
(-328…1166 °F)
200 Ω -200…630 °C
Platinum (3916)
(2)
500 Ω -200…630 °C
(-328…1166 °F)
(-328…1166 °F)
1000 Ω -200…630 °C
(-328…1166 °F)
Copper (426)
Nickel (618)
Nickel (672)
Nickel Iron (518)
(1)
The temperature range for the 1000 Ω RTD is dependant on the excitation current.
(2)
The digits following the RTD type represent the temperature coefficient of resistance (∝), which is defined as the resistance change per ohm per °C. For
instance, Platinum 385 refers to a platinum RTD with ∝ = 0.00385 Ω/Ω -°C or simply 0.00385 /°C.
(3)
Actual value at 0 °C (32 °F) is 9.042 Ω per SAMA standard RC21-4-1966.
(4)
To maximize the relatively small RTD unit signal, only 2 mA excitation current is allowed.
(5)
Actual value at 0 °C (32 °F) is 100 Ω per DIN standard.
(2)(3)
(2)(5)
(2)
(2)
10 Ω
Not allowed
120 Ω -100…260 °C
(-148 …500 °F)
120 Ω -80 …260 °C
(-112 …500 °F)
604 Ω -100…200 °C
(-148…392 °F)
(4)
Temperature Range
(1)
(2.0 mA excitation)
(-328…1562 °F)
(-328…1562 °F)
(-328…1562 °F)
(-328…464 °F)
(-328…1166 °F)
(-328…1166 °F)
(-328 …1166 °F)
(-328…446 °F)
(-148…500 °F)
(-148…500 °F)
(-112 …500 °F
(-148…392 °F)
-200…850 °C
-200…850 °C
-200…850 °C
-200…240 °C
-200 …630 °C
-200…630 °C
-200…630 °C
-200…630 °C
-100…260 °C
-100…260 °C
-80 …260 °C
-100…200 °C
Resolution Repeatability
(1)
0.1 °C
(0.2 °F)
0.1 °C
(0.2 °F)
0.1 °C
(0.2 °F)
0.1 °C
(0.2 °F)
0.1 °C
(0.2 °F)
0.1 °C
(0.2 °F)
0.1 °C
(0.2 °F)
0.1 °C
(0.2 °F)
0.1 °C
(0.2 °F)
0.1 °C
(0.2 °F)
0.1 °C
(0.2 °F)
0.1 °C
(0.2 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.1 °C
(±0.2 °F)
±0.1 °C
(±0.2 °F)
±0.1 °C
(±0.2 °F)
Publication 1746-UM008B-EN-P - December 2006
14 Overview
IMPORTANT
This table shows the accuracy and temperature drift.
Accuracy and Temperature Drift Specifications
RTD Unit Type Accuracy
(0.5 mA excitation)
Platinum (385)
Platinum (3916)
100 Ω ±0.1 °C
200 Ω ±0.1 °C
(3)
500 Ω ±0.6 °C
1000 Ω ±0.6 °C
100 Ω ±1.0 °C
200 Ω ±1.0 °C
(3)
500 Ω ±0.5 °C
(±2.0 °F)
(±2.0 °F)
(±1.1 °F)
(±1.1 °F)
(±2.0 °F)
(±2.0 °F)
(±0.9 °F)
The exact signal range valid for each input type is dependent
upon the excitation current magnitude that you select when
configuring the module.
For details on excitation current, refer to page 119.
Accuracy
(1)
(0.2 mA excitation)
±0.5 °C
(±0.9 °F)
±0.5 °C
(±0.9 °F)
±0.5 °C
(±0.9 °F)
±0.5 °C
(±0.9 °F)
±0.4 °C
(±0.7 °F)
±0.4 °C
(±0.7 °F)
±0.4 °C
(±0.7 °F)
Temperature Drift
(1)
(0.5 mA excitation)
±0.034 °C/°C
(±0.061 °F/°F)
±0.034 °C/°C
(±0.061 °F/°F)
±0.017 °C/°C
(±0.031 °F/°F)
±0.017 °C/°C
(±0.031 °F/°F)
±0.034 °C/°C
(±0.061 °F/°F)
±0.034 °C/°C
(±0.061 °F/°F)
±0.014 °C/°C
(±0.025 °F/°F)
Temperature Drift
(2)
(0.2 mA excitation)
±0.014 °C/°C
(±0.025 °F/°F)
±0.014 °C/°C
(±0.025 °F/°F)
±0.014 °C/°C
(±0.025 °F/°F)
±0.014 °C/°C
(±0.025 °F/°F)
±0.011 °C/°C
(±0.020 °F/°F)
±0.011 °C/°C
(±0.020 °F/°F)
±0.014 °C/°C
(±0.025 °F/°F)
(2)
1000 Ω ±0.5 °C
(±0.9 °F)
Copper (426)
Nickel (618)
Nickel (672)
Nickel Iron (518)
(1)
The accuracy values assume that the module was calibrated within the specified temperature range of 0…60 °C (32…140 °F).
(2)
Temperature drift specifications apply to a module that has not been calibrated.
(3)
The digits following the RTD unit type represent the temperature coefficient of resistance (∝), which is defined as the resistance change per ohm per °C. For instance,
Platinum 385 refers to a platinum RTD with ∝ = 0.00385 Ω/Ω -°C or simply 0.00385 /°C.
(4)
Actual value at 0 °C (32 °F) is 9.042 Ω per SAMA standard RC21-4-1966.
(5)
To maximize the relatively small RTD unit signal, only 2 mA excitation current is allowed.
(6)
Actual value at 0 °C (32 °F) is 100 Ω per DIN standard.
(3)(4)
(3)(6)
(3)
(3)
10 Ω
Not allowed.
120 Ω ±0.2 °C
(±0.4 °F)
120 Ω ±0.2 °C
(±0.4 °F)
604 Ω ±0.3 °C
(±0.5 °F)
(5)
±0.4 °C
(±0.7 °F)
±0.6 °C
(±1.1 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.3 °C
(±0.5 °F)
±0.014 °C/°C
(±0.025 °F/°F)
Not allowed.
±0.008 °C/°
(±0.014 °F/°F)
±0.008 °C/°
(±0.014 °F/°F)
±0.010 °C/°
(±0.018 °F/°F)
±0.014 °C/°C
(±0.025 °F/°F)
(5)
±0.017 °C/°C
(±0.031 °F/°F)
±0.008 °C/°C
(±0.014 °F/°F)
±0.008 °C/°C
(±0.014 °F/°F)
±0.010 °C/°C
(±0.018 °F/°F)
Publication 1746-UM008B-EN-P - December 2006
Overview 15
When you are using 100 Ω or 200 Ω platinum RTD units with 0.5 mA
excitation current, refer to the following important information about
module accuracy.
IMPORTANT
Module accuracy, using 100 Ω or 200 Ω platinum RTD units with 0.5 mA
excitation current, depends on the following criteria:
• Module accuracy is ±0.6 °C (±33.08 °F) after you apply power to the
module or perform an autocalibration at 25 °C (77 °F) ambient with
module operating temperature at 25 °C (77 °F).
• Module accuracy is ±(0.6 °C + ΔT x 0.034 °C/°C) or
±(33.08 °F + ΔT x 32.06 °F/°F) after you apply power to the module or
perform an autocalibration at 25 °C (77 °F) ambient with the module
operating temperature between 0…60 °C. (32…140 °F).
Where ΔT is the temperature difference between the actual
operating temperature of the module and 25 °C (77 °F) and
0.034 °C/°C (32.06 °F/°F) is the temperature drift shown in the table
above for 100 Ω or 200 Ω platinum RTD units.
Module accuracy is ±1.0 °C (±33.80 °F) after you apply power to the
module or perform an autocalibration at 60 °C (140 °F) ambient with
module operating temperature at 60 °C (140 °F).
Publication 1746-UM008B-EN-P - December 2006
16 Overview
Resistance Input Specifications
Resistance Device Compatibility
The following table lists the resistance input types you can use with
the RTD module and gives each type’s associated specifications.
Input Type Resistance Range
(0.5 mA excitation)
150 Δ 0…150 Δ 0…150 Δ
Resistance Range
(2.0 mA excitation)
Accuracy
(2) (3)
(1)
Temperature
Drift
500 Δ 0…500 Δ 0…500 Δ x 0.5 Δ x 0.014 Δ/ ° C
(x 0.025 Δ/ ° F
Resistance
1000 Δ 0…1000 Δ 0…1000 Δ x 1.0 Δ x 0.029 Δ/ °C
(x 0.052 Δ/ ° F
3000 Δ 0…3000 Δ 0…1900 Δ x 1.5 Δ x 0.043 Δ/ °C
(x 0.077 Δ/ ° F
(1)
The accuracy values assume that the module was calibrated within the specified temperature range of 0…60 °C (32 …140 °F).
(2)
The accuracy for 150 Ω is dependant on the excitation current:
x 0.2 Ω at 0.5 mA
x 0.15 Ω at 2.0 mA
(3)
The temperature drift for 150 Ω is dependant on the excitation current:
x 0.006 Ω/°C at 0.5 mA
x 0.004Ω at 2.0 mA
Hardware Overview
Resolution Repeatability
0.01Δ x 0.04 Δ
0.01Δ x 0.2 Δ
0.01Δ x 0.2 Δ
0.01Δ x 0.2 Δ
Publication 1746-UM008B-EN-P - December 2006
The RTD module fits into a single-slot of an SLC 500 chassis.
• Modular system, except the processor slot (0)
• Fixed system expansion chassis (1746-A2)
The module uses eight input words and eight output words.
IMPORTANT
If the RTD module resides in a remote configuration with a
SLC 500 Remote I/O Adapter Module (1747-ASB), use block
transfer for configuration and data retrieval. Block transfer
requires a 1747-SN Remote I/O Scanner (series B) or PLC
processor.
The module contains a removable terminal block (item 3) 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.
Overview 17
RTD Module Hardware
6
1
2
3
4
CHANNEL
STATUS
MODULE STA
RTD/resistance
INPUT
SHIELD
CHL 0
RTD
CHL 0
SENSE
CHL 0
RETRN
SHIELD
CHL 2
RTD
CHL 2
SENSE
CHL 2
RETRN
SHIELD
SHIELD
CHL 1
RTD
CHL 1
SENSE
CHL 1
RETRN
SHIELD
CHL 3
RTD
CHL 3
SENSE
CHL 3
RETRN
SHIELD
5
012
3
TUS
CAT
SERIAL NO.
1746 NR4
NR4±xxx x
RTD/resistance INPUT MODULE
SLC 500
SER
FRN
)
CLASS I, GROUPS A, B, C AND D, DIV.2
U
L
LISTED IND. CONT . EQ.
FOR HAZ. LOC. A196
SA
)
OPERA TING
TEMPERA TURE
CODE T3C
RESIST ANCE:
RTD TYPES:
INPUT SIGNAL RANGES
150 W , 500 W , 1000 W , 3000 W
PLATINUM, COPPER
NICKEL, NICKEL±IRON
7
Hardware Features
Feature Description
1 Channel Status LED Indicators
(green)
Display operating and fault status of
channels 0, 1, 2, and 3
2 Module Status LED (green) Displays module operating and fault status
3 Removable Terminal Block Provides physical connection to input devices
4 Cable Tie Slots Secure wiring from module
5 Door Label Provides terminal identification
6 Side Label (Nameplate) Provides module information
7 Self-locking Tabs Secure module in chassis slot
General Diagnostic Features
The RTD module contains diagnostic features that can be used to help
you identify the source of problems that may occur while you turn on
the power or during normal channel operation.
The power and channel diagnostics are explained in Chapter 7,
Module Diagnostics and Troubleshooting.
Publication 1746-UM008B-EN-P - December 2006
18 Overview
System Overview
The RTD module communicates to the SLC 500 processor through the
parallel backplane interface and receives +5V dc and +24V dc power
from the SLC 500 power supply through the backplane. No external
power supply is required. You may install as many RTD modules in
your system as the power supply can support.
RTD Module Configuration
RTD Modules
SLC Processor
Each individual channel on the RTD module can receive input signals
from two, three or four wire RTD sensors or from resistance input
devices. You configure each channel to accept either input. When
configured for RTD input types, the module converts the RTD
readings into linearized, digital temperature readings in °C or °F.
When configured for resistance inputs, the module provides a linear
resistance value in ohms.
IMPORTANT
The RTD module is designed to accept input from RTD sensors
with up to three wires. When using 4-wire RTD sensors, one of
the two lead compensation wires is not used and the 4-wire
sensor is treated like a 3-wire sensor. Lead wire compensation
is provided via the third wire.
See NR4 Wiring Considerations on page 40 for more
information.
Publication 1746-UM008B-EN-P - December 2006
Overview 19
System Operation
The RTD module has three operational states.
• Cycle power
• Module operation
• Error (module error and channel error)
Cycle Power
When you cycle the module’s power, the RTD module checks its
internal circuits, memory, and basic functions via hardware and
software diagnostics. During this time the module status LED indicator
remains off. If no faults are found during the diagnostics, the module
status LED indicator is on.
After the checks are complete, the RTD module waits for valid
channel configuration data from your SLC ladder logic program
(channel status LED indicators off). After configuration data is written
to one or more channel configuration words and their channel enable
bits are set by the user program, the channel status LED indicators go
on and the module continuously converts the RTD or resistance input
to a value within the range you selected for the enabled channels. The
module is now operating in its normal state.
Each time a channel is read by the module, that data value is tested by
the module for a fault condition, for example, open circuit, short
circuit, over range, and under range. If such a condition is detected, a
unique bit is set in the channel status word and the channel status
LED indicator blinks, indicating a channel error condition.
The SLC processor reads the converted RTD or resistance data from
the module at the end of the program scan or when commanded by
the ladder program. The processor and RTD module determine that
the backplane data transfer was made without error and the data is
used in your ladder program.
Module Operation
Each input channel consists of an RTD connection, which provides:
• excitation current.
• a sense connection, which detects lead-wire resistance.
• a return connection, which reads the RTD or resistance value.
Each of these analog inputs are multiplexed to one of two analog
convertors.
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20 Overview
The A/D convertors cycle between reading the RTD or resistance
value, the lead wire resistance, and the excitation current. From these
readings, an accurate temperature or resistance is returned to the user
program.
The RTD module is isolated from the chassis backplane and chassis
ground. The isolation is limited to 500V dc. Optocouplers are used to
communicate across the isolation barrier. Channel-to-channel
common-mode isolation is limited to X 1 volt.
LED Indicator Status
The following figure shows the RTD module LED indicator panel
consisting of five LED indicators. The state of the LED indicators (for
example, off, on, or blinking) depends on the operational state of the
module.
See the LED Indicator Status table on page 21.
LED Indicators
INPUT
CHANNEL
STATUS
MODULE STATUS
RTD/resistance
The purpose of the LED indicators is to provide:
• Channel Status - One LED indicator for each of the four input
channels indicates if the channel is enabled, disabled, or is not
operating as configured, due to an error.
• Module Status - If OFF at any time, other than when you cycle
module power, this LED indicator indicates that non-recoverable
module errors (for example, diagnostic or operating errors) have
occurred. The LED indicator is ON if there are no module errors.
0 2
1 3
Publication 1746-UM008B-EN-P - December 2006
Overview 21
The status of each LED indicator, during each of the operational states
(for example, powerup, module operation and error), is depicted in
the following table.
LED Indicator Status
LED Indicator Cycle
Power
Ch 0 Status
Ch 1 Status
Ch 2 Status
Ch 3 Status
Mod. Status
(1)
Module is disabled while you cycle module power.
(2)
Channel status LED indicator is ON if the respective channel is enabled and OFF if the channel is disabled.
Off
Off
Off
Off
Off
(1)
(1)
(1)
(1)
(1)
Module Operation
(No Error)
(2)
On/Off
(2)
On/Off
(2)
On/Off
(2)
On/Off
Module Error Channel
Error
Off Blinks
Off Blinks
Off Blinks
Off Blinks
On Off On
Module to Processor Communication
The RTD module communicates with the SLC processor through the
backplane of the chassis. The RTD module transfers data to and
receives data from the processor by means of an image table. The
image table consists of eight input words and eight output words.
Data transmitted from the module to the processor is called the input
image (for example, Channel Data Words and Channel Status Words).
Conversely, data transmitted from the processor to the module is
called the output image (for example, Channel Configuration Words
and Scaling Limit Words).
Details about the input and output images are found in Module
Addressing on page 52 and 53.
Communication Flow
Channel Data Words
RTD/
resistance
Analog
Signals
1746-NR4
Input
Module
Channel Status Words
Scaling Limit Words
Channel Configuration Words
Publication 1746-UM008B-EN-P - December 2006
SLC 500
Processor
22 Overview
Image Table
Input Image
Word
0 Channel 0 data 0 Channel 0 configuration
1 Channel 1 data 1 Channel 1 configuration
2 Channel 2 data 2 Channel 2 configuration
3 Channel 3 data 3 Channel 3 configuration
4 Channel 4 data 4 User-set Lower limit scale 0
5 Channel 5 data 5 User-set Upper limit scale 0
6 Channel 6 data 6 User-set Lower limit scale 1
7 Channel 7 data 7 User-set Upper limit scale 1
Function Output
Image Word
Function
The Channel Configuration Words (output image) contain
user-defined configuration information for the specified input channel.
This information is used by the module to configure and operate each
channel. The Channel Status Words (input image) contain status
information about the channel’s current configuration and operational
state. The input data values of the analog input channel are contained
in the Channel Data Word (input image), which is valid only when the
channel is enabled and there are no channel errors (for example,
broken sensor or overrange.)
You set the Scaling Limit Words (output image) to provide a definable
scaling range for the temperature resistance data when using the
proportional counts data type.
Publication 1746-UM008B-EN-P - December 2006
Chapter
2
Quick Start Guide
This chapter helps you get started using the RTD module. The
procedures included here assume that you have a basic understanding
of SLC 500 products.
You must:
• understand electronic process control.
• be able to interpret the ladder logic instructions for generating
the electronic signals that control your application.
Because this is a start-up guide, this chapter does not contain detailed
explanations about the procedures listed. It does, however, reference
other chapters in this book where you can get more detailed
information.
Required Tools and Equipment
If you have any questions or are unfamiliar with the terms used or
concepts presented in the procedural steps, always read the
referenced chapters and other recommended documentation before
trying to apply the information.
This chapter:
• tells you what equipment you need.
• explains how to install and wire the module.
• shows you how to set up one channel for RTD or resistance
input.
• examines the state of the LED indicators at normal startup.
• examines the channel status word.
Have the following tools and equipment ready.
• Medium blade screwdriver
• Medium cross-head screwdriver
• RTD module (1746-NR4)
• RTD sensor or resistance input
• Appropriate cable (if needed)
• Programming software
23 Publication 1746-UM008B-EN-P - December 2006
24 Quick Start Guide
Procedures
Follow these procedures to get your RTD module installed and ready
to use.
Unpack the Module
Unpack the module making sure that the contents include:
• RTD module, catalog number 1746-NR4.
• Installation instructions, publication 1746-IN012.
If the contents are incomplete contact your Allen-Bradley
representative for assistance.
Determine Power Requirements
Review the requirements of your system to see that your chassis
supports placement of the RTD module.
• The fixed, 2-slot chassis supports two RTD modules.
If combining an RTD module with a different module, refer to
the module compatibility table found in chapter 3.
• For modular style systems, calculate the total load on the system
power supply using the procedure described in the SLC 500
Modular Style User Manual, publication 1747-UM011.
For more information refer to chapter 3, Install and Wire and
Appendix A, Specifications.
Publication 1746-UM008B-EN-P - December 2006
Insert the Module
Quick Start Guide 25
ATTENTION
Never install, remove, or wire modules with power applied to
the chassis or devices wired to the module.
For more information refer to chapter 3, Install and Wire.
Make sure system power is off; then insert the RTD module into your
1746 chassis. In this example procedure, local slot 1 is selected.
Module Insertion into Chassis
Top and Bottom
Module Release(s)
Card Guide
Wire the Module
Connect RTD module or potentiometer wire leads to channel 0 of the
RTD module.
See RTD Connections to Terminal Block on page 26, Two-wire
Potentiometer Connections to Terminal Block on page 27, or
Three-wire Potentiometer Connections to Terminal Block on page 28.
For more information refer to chapter 3, Install and Wire.
Publication 1746-UM008B-EN-P - December 2006
26 Quick Start Guide
RTD Connections to Terminal Block
For details on wiring an RTD unit to the module, see chapter 3.
Two Wire RTD Interconnection
Add jumper.
Shield
Chl 0 RTD
Chl 0 Sense
Chl 0 Return
Three Wire RTD Interconnection
Shield
Chl 0 RTD
Chl 0 Sense
Chl 0 Return
Four Wire RTD Interconnection
Cable Shield
RTD
Return
Belden #9501 Shielded Cable
Cable Shield
RTD
Sense
Return
Belden #83503 or Belden #9533 Shielded Cable
Cable Shield
RTD
Return
RTD
Sense
Return
Terminal Pin-outs
Shield
Shield
Chl 0
RT D
Chl 1
RT D
Chl 0
Sense
Chl 1
Sense
Chl 0
Return
Chl 1
Return
Shield
Shield
Chl 2
RT D
Chl 3
RT D
Chl 2
Sense
Chl 3
Sense
Chl 2
Return
Chl 3
Return
Shield
Shield
Shield
Chl 0 RTD
Chl 0 Sense
Chl 0 Return
RTD
Sense
Return
Belden #83503 or Belden #9533 Shielded Cable
Leave one sensor wire open
RTD
Sense
Return
Publication 1746-UM008B-EN-P - December 2006
Two-wire Potentiometer Connections to Terminal Block
For details on wiring an RTD unit to the module, see chapter 3.
Cable Shield
Quick Start Guide 27
Add jumper.
Add jumper.
Shield
Chl 0 RTD
Chl 0 Sense
Chl 0 Return
Shield
Chl 0 RTD
Chl 0 Sense
Chl 0 Return
RTD
Return
Belden #9501 Shielded Cable
Potentiometer wiper arm can be connected to either the RTD or return terminal
depending on whether the user wants increasing or decreasing resistance.
RTD
Return
Belden #9501 Shielded Cable
Potentiometer
Potentiometer
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28 Quick Start Guide
Three-wire Potentiometer Connections to Terminal Block
For details on wiring an RTD to the module, see chapter 3.
Cable Shield Run RTD unit and sense wires from module to
potentiometer terminal and tie them to one point.
Shield
Chl 0 RTD
Chl 0 Sense
Chl 0 Return
Shield
Chl 0 RTD
Chl 0 Sense
Chl 0 Return
RTD
Sense
Return
Belden #83503 or Belden #9533 Shielded Cable
Potentiometer wiper arm can be connected to either the RTD or return terminal
depending on whether you want increasing or decreasing resistance.
Cable Shield
RTD
Sense
Return
Belden #83503 or Belden #9533 Shielded Cable
Run RTD and sense wires from module to
potentiometer terminal and tie them to one point.
Potentiometer
Potentiometer
Publication 1746-UM008B-EN-P - December 2006
Configure Your I/O
Configure your system I/O configuration for the particular slot where
the RTD module resides (slot 1 in this example). Select the 1746-NR4
module from the list of modules, or if it is not listed in your software
version, select Other and enter the RTD module ID code (3513) at the
prompt on the I/O configuration display.
For more information refer to chapter 4, Preliminary Operating
Considerations.
Quick Start Guide 29
Configure the Module
Determine the operating parameters for channel 0. In this example,
the figure shows the channel 0 configuration word defined with all
defaults (0) except for channel enable (bit 11). The addressing reflects
the location of the module as slot 1.
For details on how to configure the module for your application, refer
to chapter 4 and chapter 5.
A configuration worksheet is included on page 132 to assist you in
channel configuration.
For more information refer to chapter 5, Channel Configuration, Data,
and Status.
Output Image Detail
SLC 500 Controller
Data Files
Input Image
Address
Word 0
O:1.0
Word 1
O:1.1
Word 2
O:1.2
Word 3
O:1.3
Word 4
O:1.4
Word 5
O:1.5
Word 6
O:1.6
Word 7
O:1.7
If proportional counts data format is used, then output words 4…7
can be used to define a user-set scaling range for each channel.
Output Image
(8 words)
Channel 0 Configuration Word
Channel 1 Configuration Word
Channel 2 Configuration Word
Channel 3 Configuration Word
User-set Lower Scale Limit Range 0
User-set Upper Scale Limit Range 0
User-set Lower Scale Limit Range 1
User-set Upper Scale Limit Range 1
Not Defined
Excitation Current Select
Scaling Select *
Filter Frequency Select
Channel Enable
Temperature Units Select
000000000000000
Bit 15 Bit 0
Data Format Select
Broken Input Select
Input T ype Select
0
* Scaling Select bits apply to proportional counts mode.
Limit Scale W ords are only used if scaling select = 01
10 and data format = 11.
Default Settings
• 100 Platinum R TD (385)
• Engineering
Units x 1 (0.1
˚/ step)
• Broken Input (set data word to zero)
• Degrees Celsius ( ˚C)
• 10
Hz Filter Frequency
• Channel Disabled
• 2.0 mA Excitation Current
• Module Defined Scaling
Bit 15
000010000000000
New Setting
Bit 0
0
or
Set this bit (11) to enable channel. Address = O:1.0/11
Publication 1746-UM008B-EN-P - December 2006
30 Quick Start Guide
n
Program the Configuration
Follow these steps to complete the programming necessary to
establish the new configuration word setting in the previous step.
1. Create integer file N10 using the memory map function.
Integer file N10 should contain one element for each channel
used. For this example we only need one, N10:0.
2. Enter the configuration parameters for channel 0 into integer
N10:0.
In this example, all the bits of N10:0 are zero except for the
channel enable (N10:0/11).
3. Program an instruction in your ladder logic to copy the contents
of N10:0 to output word O:1.0.
See Output Image Detail on page 28.
For more information refer to chapter 6, Ladder Programming
Examples and chapter 8, Application Examples.
Initial Configuration Word Setting
First Pass Bit
S:1
] [
15
COP
COPY FILE
Source # N10:0
Dest # O:1.0
Length 1
On power±up, the first pass bit
(S:1/15) is set for one scan, enabling
the COPY instruction that transfers a
one to bit 11 of channel configuration
word 0. This enables channel 0,
which directs the RTD module to sca
channel 0 and to present the analog
data to the SLC processor.
Publication 1746-UM008B-EN-P - December 2006
Quick Start Guide 31
Write Remaining Ladder Logic
The Channel Data Word contains the information that represents the
temperature value or resistance value of the input channel. Write the
remainder of the ladder logic program that specifies how your
RTD/resistance input data is processed for your application. In this
procedure, the addressing reflects the location of the module as slot 1.
Input Image Detail
SLC 500 Controller
Data Files
Address
I:1.0
I:1.1
I:1.2
I:1.3
•
•
•
I:1.7
Word 0
Word 1
Word 2
Word 3
•
•
•
Word 7
Input Image
(8 words)
Channel 0 Data Word
Channel 1 Data Word
Channel 2 Data Word
Channel 3 Data Word
Channel 0 Status Word
Channel 1 Status Word
Channel 2 Status Word
Channel 3 Status Word
Output Image
Address
I:1.0
000000000000000
(Variable RTD/resistance Input Data)
Bit 15
0
Bit 0
Test Your RTD Program
1. Apply power.
The module status LED indicator and channel 0 status LED
indicator turn on.
2. Download your program to the SLC processor.
3. Make sure the controller is in Run mode.
For more information see chapter 7, Module Diagnostics and
Troubleshooting.
LED Indicator Status
INPUT
CHANNEL
STATUS
MODULE STATUS
RTD/resistance
012
3
Channel LEDs
Module Status LED
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32 Quick Start Guide
Program Functional Check (Optional)
Monitor the status of input channel 0 to determine its configuration
setting and operational status. This is useful for troubleshooting when
the blinking channel LED indicator indicates that an error has
occurred.
If the Module Status LED indicator is off, or if the Channel 0 LED
indicator is off or blinking, refer to chapter 7.
For more information see chapter 5, chapter 7, and chapter 8.
Monitoring Status
SLC 500 Controller
Data Files
Input Image
(8 words)
Output Image
Word 1
Word 2
Word 3
Word 7
Channel 0 Data WordWord 0
Channel 1 Data Word
Channel 2 Data Word
Channel 3 Data Word
Channel 0 Status Word
Channel 1 Status Word
Channel 2 Status Word
Channel 3 Status Word
Broken Input Error
Configuration Error
Excitation Current
Out±Of±Range Error
Broken Input
Temperature Units
Data Format
Filter Frequency
Channel Status
000010000000000
Bit 15
Address
Input Type
0
Bit 0
I:1.4
For this example, only bit 11 is set during normal operation.
Publication 1746-UM008B-EN-P - December 2006
Chapter
3
Install and Wire the Module
This chapter tells you how to:
• avoid electrostatic damage.
• determine the RTD module’s chassis power requirement.
• choose a location for the RTD module in the SLC chassis.
• install the RTD module.
• wire the RTD module’s terminal block.
If this product has the CE mark it is approved for installation within
the European Union and EEA regions. It has been designed and tested
to meet the following directives.
EMC Directive
Electrostatic Damage
This product is tested to meet Council Directive 89/336/EEC
Electromagnetic Compatibility (EMC) and the following standards, in
whole or in part, documented in a technical construction file:
• EN 50081–2
EMC - Generic Emission Standard, Part 2 - Industrial
Environment
• EN 50082–2
EMC - Generic Immunity Standard, Part 2 - Industrial
Environment
This product is intended for use in an industrial environment.
Electrostatic discharge can damage semiconductor devices inside this
module if you touch backplane connector pins or other sensitive
areas. Guard against electrostatic damage by observing the
precautions listed next.
ATTENTION
Electrostatic discharge can degrade performance or cause
permanent damage. Handle the module as stated below.
Wear an approved wrist strap grounding device when handling the
module.
33 Publication 1746-UM008B-EN-P - December 2006
34 Install and Wire the Module
• Touch a grounded object to rid yourself of electrostatic charge
before handling the module.
• Handle the module from the front, away from the backplane
connector. Do not touch backplane connector pins.
• Keep the module in its static-shield bag when not in use, or
during shipment.
NR4 Power Requirements
The RTD module receives its power through the SLC 500 chassis
backplane from the fixed or modular +5V dc/+24V dc chassis power
supply. The maximum current drawn by the module is shown in the
table below.
5V dc Amps 24V dc Amps
0.050 0.050
When you are using a modular system configuration, add the values
shown in the table above to the requirements of all other modules in
the SLC chassis to prevent overloading the chassis power supply.
When you are using a fixed system controller, refer to the Important
note about module compatibility in a two-slot expansion chassis on
page 35.
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Install and Wire the Module 35
Module Location in Chassis
This section contains information on module location in modular and
fixed chassis.
Modular Chassis Considerations
Place your RTD module in any slot of an SLC 500 modular chassis
(except slot 0) or a modular expansion chassis. Slot 0 is reserved for
the modular processor or adapter modules.
Fixed Expansion Chassis Considerations
IMPORTANT
The 2-slot, SLC 500 fixed I/O expansion chassis (1746-A2)
supports only specific combinations of modules. If you are using
the RTD module in a 2-slot expansion chassis with another SLC
I/O or communication module, refer to the Fixed Controller
Compatibility Table to determine whether the combination can
be supported.
When using the Fixed Controller Compatibility Table, be aware that
there are certain conditions that affect the compatibility characteristics
of the BASIC module (BAS) and the DH-485/RS-232C module (KE).
When you use the BAS module or the KE module to supply power to
a 1747-AIC Link Coupler, the link coupler draws its power through the
module. The higher current drawn by the AIC at 24V dc is calculated
and recorded in the table for the modules identified as BASn (BAS
networked) or KEn (KE networked). Make sure to refer to these
modules if your application uses the BAS or KE module in this way.
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36 Install and Wire the Module
Fixed Controller Compatibility Table
Modules NR4 5V dc (Amps) 24V dc (Amps)
IA4
(1)
•
0.035 -
IA8 • 0.050 IA16 • 0.085 IM4 • 0.035 IM8 • 0.050 IM16 • 0.085 OA8 • 0.185 OA16 • 0.370 OAP12 • 0.370 IB8 • 0.050 IB16 • 0.085 IV8 • 0.050 IV16 • 0.085 IG16 • 0.140 IH16 • 0.085 OV8 • 0.135 OV16 • 0.270 OB8 • 0.135 OBP8 • 0.135 OG16 • 0.180 OW4 • 0.045 0.045
OW8 • 0.085 0.090
OW16
(2)
0.170 0.180
IO4 • 0.030 0.025
IO8 • 0.060 0.045
IO12 • 0.090 0.070
NI4 • 0.025 0.085
NI8 • 0.200 0.100
NIO4I • 0.055 0.145
NIO4V • 0.055 0.115
FIO4I • 0.055 0.150
FIO4V • 0.055 0.120
DCM • 0.360 HS • 0.300 OB16 • 0.280 OB16E • 0.135 IN16 • 0.085 BASn • 0.150 0.125
BAS • 0.150 0.040
OB32 0.452 OV32 0.452 IV32 • 0.106 IB32 • 0.106 -
Publication 1746-UM008B-EN-P - December 2006
Install and Wire the Module 37
Fixed Controller Compatibility Table
Modules NR4 5V dc (Amps) 24V dc (Amps)
OX8 • 0.085 0.090
NO4I
(3)
Δ
0.055 0.195
NO4V • 0.055 0.145
ITB16 • 0.085 ITV16 • 0.085 IC16 • 0.085 KE • 0.150 0.40
KEn • 0.150 0.145
OBP16 • 0.250 OVP16 • 0.250 NT4 • 0.060 0.040
NR4 • 0.050 0.050
HSTP1 • 0.200 -
(1)
A dot indicates a valid combination.
(2)
No symbol indicates an invalid combination.
(3)
A triangle indicates an external power supply is required.
General Considerations
Most applications require installation in an industrial enclosure to
reduce the effects of electrical interference. RTD inputs are susceptible
to electrical noises due to the small amplitudes of their signal.
Group your modules to minimize adverse effects from radiated
electrical noise and heat. Consider the following conditions when
selecting a slot for the RTD module. Position the module in a slot:
• away from power lines, load lines and other sources of electrical
noise such as hard-contact switches, relays, and AC motor
drives.
• away from modules which generate significant radiated heat,
such as the 32-point I/O modules.
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38 Install and Wire the Module
Module Installation and Removal
When installing the module in a chassis, it is not necessary to remove
the terminal block from the module. However, if the terminal block is
removed, use the write-on label located on the side of the terminal
block to identify the module location and type.
Write-on Label
SLOT ____ RACK ____
MODULE _______________
•
Remove the Terminal Block
ATTENTION
1. Loosen the two terminal block release screws.
Never install, remove or wire modules with power applied to
the chassis or devices wired to the module. To avoid cracking
the removable terminal block alternate the removal of the
slotted terminal block release screws.
Terminal Block Release Screws
Max. Torque = 0.6 Nm (5.3 in-lbs)
2. Grasp the terminal block at the top and bottom and pull
outward and down.
Publication 1746-UM008B-EN-P - December 2006
Install and Wire the Module 39
Install the Module
1. Align the circuit board of the RTD module with the card guides
located at the top and bottom of the chassis.
Top and Bottom
Module Release(s)
Card
Guide
2. Slide the module into the chassis until both top and bottom
retaining clips are secured. Apply firm even pressure on the
module to attach it to its backplane connector. Never force the
module into the slot.
3. Cover all unused slots with the Card Slot Filler, catalog number
1746-N2.
Remove the Module
1. Press the releases at the top and bottom of the module and slide
the module out of the chassis slot.
2. Cover all unused slots with the Card Slot Filler, Catalog Number
1746-N2.
Publication 1746-UM008B-EN-P - December 2006
40 Install and Wire the Module
Terminal Wiring
The RTD module contains an 18-position, removable terminal block.
The terminal pin-out is shown in RTD Connections to Terminal Block
on page 42.
ATTENTION
Disconnect power to the SLC before attempting to install,
remove, or wire the removable terminal wiring block.
To avoid cracking the removable terminal block, alternate the
removal of the terminal block release screws.
Terminal Block
Release Screw
Max. Torque =
Shield
Channel 0 RTD
Channel 0 Sense
Channel 0 Return
Shield
Channel 2 RTD
Channel 2 Sense
Channel 2 Return
Shield
Release Screw
Max. Torque =
0.6 Nm (5.3 in-bs)
0.6 Nm (5.3 in-bs)
Shield
Channel 1 RTD
Channel 1 Sense
Channel 1 Return
Shield
Channel 3 RTD
Channel 3 Sense
Channel 3 Return
Shield
Publication 1746-UM008B-EN-P - December 2006
NR4 Wiring Considerations
Follow the guidelines below when planning your system wiring.
Since the operating principle of the RTD module is based on the
measurement of resistance, take special care in selecting your input
cable. For 2–wire or 3–wire configuration, select a cable that has a
consistent impedance throughout its entire length.
Cable Selection
Configuration Recommended Cable
Two-wire Belden #9501 or equivalent
Three-wire less than 30.48 m (100 ft) Belden #9533 or equivalent
Three-wire greater than 30.48 m (100 ft) or
high humidity conditions
Belden #83503 or equivalent
Install and Wire the Module 41
For a three-wire configuration, the module can compensate for a
maximum cable length associated with an overall cable impedance of
25 ohms.
IMPORTANT
Details of cable specifications are shown on page 122.
As shown in RTD Connections to Terminal Block on page 42, three
configurations of RTDs can be connected to the RTD module, namely:
• two-wire RTD, which is composed of two RTD lead wires (RTD
and Return).
• three-wire RTD, which is composed of a Sense and two RTD
lead wires (RTD and Return).
• four-wire RTD, which is composed of two Sense and two RTD
lead wires (RTD and Return). The second sense wire of a
four-wire RTD is left open. It does not matter which sense wire
is left open.
IMPORTANT
The RTD module requires three wires to compensate for lead
resistance error. It is recommended that you do not use
two-wire RTDs if long cable runs are required, as it will reduce
the accuracy of the system. However, if a two-wire
configuration is required, reduce the effect of the lead wire
resistance by using a lower gauge wire for the cable (for
example, use 1.291 mm (16 AWG) instead of 0.511 mm
(24 AWG)). Also, use cable that has a lower resistance per foot
of wire. The module’s terminal block accepts two 2.5 mm
2
(14 AWG) gauge wires.
• To limit overall cable impedance, keep input cables as short as
possible. Locate your I/O chassis as near the RTD sensors as
your application will permit.
• Ground the shield drain wire at one end only. The preferred
location is at the RTD module. Refer to IEEE Std. 518, Section
6.4.2.7 or contact your sensor manufacturer for additional
details.
• Each input channel has a shield connection screw terminal that
provides a connection to chassis ground. All shields are
internally connected, so any shield terminal can be used with
channels 0…3.
• Route RTD/resistance input wiring away from any high-voltage
I/O wiring, power lines, and load lines.
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42 Install and Wire the Module
Two-wire RTD Interconnection
• Tighten terminal screws using a flat or cross-head screwdriver.
Each screw should be turned tight enough to immobilize the
wire’s end. Excessive tightening can strip the terminal screw.
The torque applied to each screw should not exceed 0.565 Nm
(5 in-lb) for each terminal.
• Follow system grounding and wiring guidelines found in your
SLC 500 Installation and Operation Manual, publication
1747-UM011.
RTD Connections to Terminal Block
Cable Shield
Add Jumper
Shield
Ch 0 RTD
Ch 0 Sense
Ch 0 Return
Three-wire RTD Interconnection
Shield
Ch 0 RTD
Ch 0 Sense
Ch 0 Return
Four-wire RTD Interconnection
RTD
Return
Return
RTD
Sense Sense
Return
Belden #9501 Shielded Cable
Cable Shield
Belden #83503 or Belden #9533 Shielded Cable
Cable Shield
RTD
RTD
Return
RTD
Return
Terminal Pin-outs
Shield
Shield
Chl 0
RT D
Chl 1
RT D
Chl 0
Sense
Chl 1
Sense
Chl 0
Return
Chl 1
Return
Shield
Shield
Chl 2
RT D
Chl 3
RT D
Chl 2
Sense
Chl 3
Sense
Chl 2
Return
Chl 3
Return
Shield
Shield
Shield
Ch 0 RTD
Ch 0 Sense
Ch 0 Return
Publication 1746-UM008B-EN-P - December 2006
RTD
Sense Sense
Return
Belden #83503 or Belden #9533 Shielded Cable
RTD
Return
Leave one sensor wire open
Install and Wire the Module 43
When using a three-wire configuration, the module compensates for
resistance error due to lead wire length. For example, in a three-wire
configuration, the module reads the resistance due to the length of
one of the wires and assumes that the resistance of the other wire is
equal. If the resistances of the individual lead wires are much
different, an error may exist. The closer the resistance values are to
each other, the greater the amount of error that is eliminated.
IMPORTANT
To ensure temperature or resistance value accuracy, the
resistance difference of the cable lead wires must be equal to
or less than 0.01 Ω.
There are several ways to insure that the lead values match as closely
as possible.
• Keep lead resistance as small as possible and less than 25 Ω.
• Use quality cable that has a small tolerance impedance rating.
• Use a heavy-gauge lead wire which has less resistance per foot.
Wire the Resistance Devices (Potentiometers) to the NR4 Module
Potentiometer wiring requires the same type of cable as that for the
RTD described in the previous subsection. Potentiometers can be
connected to the RTD module as a two-wire interconnection or a
three-wire interconnection.
See Two-wire Potentiometer Connections to Terminal Block, on
page 44, for 2-wire connection and Three-wire Potentiometer
Connections To Terminal Block, on page 45, for 3-wire connection.
Publication 1746-UM008B-EN-P - December 2006
44 Install and Wire the Module
Two-wire Potentiometer Connections to Terminal Block
Cable Shield
Add jumper.
Add jumper.
Shield
Chl 0 RTD
Chl 0 Sense
Chl 0 Return
Shield
Chl 0 RTD
Potentiometer
RTD
Return
Belden #9501 Shielded Cable
Potentiometer wiper arm can be connected to either the RTD or return terminal
depending on whether the user wants increasing or decreasing resistance.
RTD
Potentiometer
Chl 0 Sense
Chl 0 Return
Publication 1746-UM008B-EN-P - December 2006
Return
Belden #9501 Shielded Cable
Install and Wire the Module 45
Three-wire Potentiometer Connections To Terminal Block
Shield
Chl 0 RTD
Chl 0 Sense
Chl 0 Return
RTD
Sense
Return
Cable Shield
Belden #83503 or Belden #9533 Shielded Cable
Potentiometer wiper arm can be connected to either the RTD or return terminal
depending on whether the user wants increasing or decreasing resistance.
Cable Shield
Run RTD and sense wires from module to potentiometer
terminal and tie them to one point.
Potentiometer
Run RTD and sense wires from module to potentiometer
terminal and tie them to one point.
Shield
Chl 0 RTD
Chl 0 Sense
Chl 0 Return
RTD
Potentiometer
Sense
Return
Belden #83503 or Belden #9533 Shielded Cable
Publication 1746-UM008B-EN-P - December 2006
46 Install and Wire the Module
Follow these steps to wire your 1746-NR4 module.
1. At each end of the cable, strip some casing to expose the
individual wires.
2. Trim the signal wires to 5.08 cm (2 in.) lengths. Strip about
4.76 mm (3/16 in.) of insulation away to expose the end of the
wire.
3. At one end of the cable twist the drain wire and foil shield
together, bend them away from the cable, and apply shrink
wrap. Then earth ground at the shield terminal.
4. At the other end of the cable, cut the drain wire and foil shield
back to the cable and apply shrink wrap.
5. Connect the signal wires and cable shield to the NR4 terminal
block and the input.
Cable Examples
Signal Wire
Signal Wire
Signal Wire
Signal Wire
Signal Wire
6. Repeat steps 1 through 5 for each channel on the NR4 module.
Two-conductor Shielded Cable
Drain Wire
Drain Wire
Foil Shield
Three-conductor Shielded Cable
Foil Shield
Signal Wire
Signal Wire
Signal Wire
Signal Wire
Signal Wire
Publication 1746-UM008B-EN-P - December 2006
Install and Wire the Module 47
Calibration
The accuracy of a system that uses the RTD module is determined by:
• the accuracy of the RTD.
• resistance mismatch of the cable wires that connect the RTD to
the module.
• the accuracy of the RTD module.
For optimal performance at the customer site, the RTD module is
calibrated at the factory prior to shipment. In addition, a
self-calibration feature, called autocalibration, further ensures that the
module performs to specification over the life of the product.
Factory Calibration
The four-pin calibration connector, on the RTD module circuit board,
is used for factory setup only.
Auto-calibration
When a channel becomes enabled, the module configures the channel
and performs an auto-calibration on the channel. The channel is
selected, the excitation current is turned off, and the three input lines
for the channel are connected to analog common. The module’s A/D
converters are configured for the proper gain and filter frequency that
is appropriate for your RTD configuration. Auto-calibration performs
an A/D conversion on the zero voltage (analog common) and the
full-scale voltage (A/D reference voltage) on the following signals:
• Lead wire signal
• RTD/resistance signal
• Excitation current signal
IMPORTANT
These conversions generate offset (zero reference) and full scale (span
reference) coefficients that are saved and used by the module to
perform future A/D conversions on this channel.
Channel calibration time is shown in the Channel Calibration
Time table.
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48 Install and Wire the Module
You can command your module to perform an auto-calibration cycle
by disabling a channel, waiting for the channel status bit to change
state (1 to 0) and then re-enabling that channel. Several scan cycles
are required to perform an auto-calibration (refer to page 4-11). It is
important to remember that during auto-calibration the module is not
converting input data.
TIP
To maintain system accuracy it is recommended that
you periodically perform an autocalibration cycle:
• whenever an event occurs that greatly changes
the internal temperature of the control cabinet,
such as opening or closing its door
• at a convenient time when the system is not
making product, such as during a shift change
An auto-calibration programming example is provided in chapter 6.
Single-point Calibration
Single-point calibration is an optional procedure that can be used to
improve the accuracy of the RTD module and cable combination to
greater than +/-0.2
(122
°F) of the calibration temperature). The offset, determined by the
single-point calibration, can be used to compensate for inaccuracies in
the RTD module and cable combination.
°C (32.4 °F) (when the RTD is operating at +/-50 °C
Publication 1746-UM008B-EN-P - December 2006
After single-point calibration is performed, additional calibrations only
need to be performed if the cable is disturbed or degraded. (RTD
replacement should not affect the accuracy of the procedure.)
However, periodic auto-calibrations should be performed. Follow the
steps below to perform a single-point calibration.
1. Cycle power to the SLC 500 chassis.
2. Select a calibration temperature that is near the control point
(+/-10 °C (50
°F)).
3. Determine the exact resistance (+/-0.01 ohm) equivalent to the
calibration temperature by using a published temperature vs.
resistance chart.
4. Replace the RTD with the fixed–precision resistor. (It is
recommended that you use a 2 ppm temperature coefficient
resistor.)
Install and Wire the Module 49
5. Use the RTD module to determine the temperature equivalent to
the fixed precision resistor and cable combination.
6. Calculate the offset value by subtracting the calculated
calibration temperature from the measured temperature.
7. Reconnect the RTD to the cable.
8. Use ladder logic to apply (subtract) the offset from the measured
temperature to obtain corrected temperature.
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50 Install and Wire the Module
Notes:
Publication 1746-UM008B-EN-P - December 2006
Chapter
4
Preliminary Operating Considerations
This chapter explains how the RTD module and the SLC processor
communicate through the module’s input and output image. It lists the
preliminary setup and operation required before the RTD module can
function in a 1746 I/O system. Topics discussed include how to:
• enter the module ID code.
• address your RTD module.
• select the proper input filter for each channel.
• calculate the RTD module update time.
• interpret the RTD module response to slot disabling.
Module ID Code
The module identification code is a unique number encoded for each
1746 I/O module. The code defines for the processor the type of I/O
or specialty module residing in a specific slot in the 1746 chassis.
To manually enter the module ID code, select (other) from the list of
modules on the system I/O configuration display. The module ID
code for the RTD module, 1746-NR4, is 3513.
No special I/O configuration information is required. The module ID
code automatically assigns the correct number of input and output
words.
51 Publication 1746-UM008B-EN-P - December 2006
52 Preliminary Operating Considerations
Module Addressing
SLC 5/0X
Data Files
Slot e
Output Image
Slot e
Input Image
The memory map displays how the output and input image tables are
defined for the RTD module.
Output
Scan
Input
Scan
RTD Module
Image Table
Output Image
8 Words
Input Image
8 Words
(Class 1)
Output Image
Input Image
t 15 Bit 0
Bi
Channel 0 Configuration Word
Channel 1 Configuration Word
Channel 2 Configuration Word
Channel 3 Configuration Word
User-set Lower Scale Limit Range 0
User-set Upper Scale Limit Range 0
User-set Lower Scale Limit Range 1
User-set Upper Scale Limit Range 1
Channel 0 Data Word
Channel 1 Data Word
Channel 2 Data Word
Channel 3 Data Word
Channel 0 Status Word
Channel 1 Status Word
Channel 2 Status Word
Channel 3 Status Word
Bit 15 Bit 0
Word 0
Word 1
Word 2
Word 3
Word 4
Word 5
Word 6
Word 7
Word 0
Word 1
Word 2
Word 3
Word 4
Word 5
Word 6
Word 7
Address
O:e.0
O:e.1
O:e.2
O:e.3
O:e.4
O:e.5
O:e.6
O:e.7
Address
I:e.0
I:e.1
I:e.2
I:e.3
I:e.4
I:e.5
I:e.6
I:e.7
Output Image - Configuration Words
The 8-word, RTD module output image (defined as the output from
the CPU to the RTD module) contains information that you configure
to define the way a specific channel on the RTD module will work.
These words take the place of configuration DIP switches on the
module. Although the RTD output image is eight words long, only
output words 0…3 are used to define the operation of the module;
output words 4…7 are used for special user-set scaling using the
proportional counts data format. Each output word 0…3 configures a
single channel.
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Preliminary Operating Considerations 53
EXAMPLE
If you want to configure channel 2 on the RTD module located
in slot 4 in the SLC chassis, your address would be O:4.2
File Type
Slot
Word
O : 4 . 2
Element
Delimiter
Chapter 5, Channel Configuration, Data, and Status, gives you detailed
bit information about the content of the data word and the status
word.
Word
Delimiter
Input Image - Data Words and Status Words
The 8-word, RTD module input image (defined as the input from the
RTD module to the CPU) represents data words and status words.
Input words 0…3 (data words) hold the input data that represent the
temperature value of the RTD input or ohmic value of the resistance
inputs for channels 0…3. This data word is valid only when the
channel is enabled and there are no channel errors.
Input words 4…7 (status words) contain the status of channels 0…3
respectively. The status bits for a particular channel reflect the
configuration settings that you have entered into the output image
configuration word for that channel and provide information about
the channel’s operational state. To receive valid status information, the
channel must be enabled and the channel must have processed any
configuration changes that may have been made to the configuration
word.
EXAMPLE
To obtain the status of channel 2 (input word 6) of the RTD
module located in slot 3 in the SLC chassis, use address I:3.6.
File Type
Slot
Word
I : 3 . 6
Element Delimiter Word Delimiter
Publication 1746-UM008B-EN-P - December 2006
54 Preliminary Operating Considerations
Chapter 5, Channel Configuration, Data, and Status, gives you detailed
bit information about the content of the data word and the status
word.
The RTD module uses a digital filter that provides noise rejection for
the input signals. The digital filter is programmable, allowing you to
select from four filter frequencies for each channel. The digital filter
provides the highest noise rejection at the selected filter frequency.
Channel Filter Frequency Selection
Selecting a low value (for example, 10 Hz) for the channel filter
frequency provides greater noise rejection for a channel, but also
increases the channel update time. Selecting a high value for the
channel filter frequency provides lesser noise rejection, but decreases
the channel update time.
The Notch Frequencies table shows the available filter frequencies, as
well as the associated minimum normal mode rejection (NMR), cut-off
frequency, and step response for each filter frequency.
The figures on pages 56 and 57 show the input channel frequency
response for each filter frequency selection.
Channel Step Response
The channel filter frequency determines the channel’s step response.
The step response is the time required for the analog input signal to
reach 100% of its expected final value. This means that if an input
signal changes faster than the channel step response, a portion of that
signal will be attenuated by the channel filter. The table below shows
the step response for each filter frequency.
Publication 1746-UM008B-EN-P - December 2006
Notch Frequencies
Filter
Frequency
10 Hz 100 dB 100 dB 2.62 Hz 300 ms
50 Hz 100 dB - 13.1 Hz 60 ms
60 Hz - 100 dB 15.72 Hz 50 ms
250 Hz - - 65.5 Hz 12 ms
50 Hz NMR 60 Hz NMR Cut-off
Frequency
Step
Response
Effective Resolution
Input Type Filter Frequency
10 Hz 50 Hz 60 Hz 250 Hz
100 Ω Pt RTD (385)
(1)
±0.1 °C
(±0.2 °F)
200 Ω Pt RTD (385)
(1)
±0.1 °C
(±0.2 °F)
500 Ω Pt RTD (385)
(1)
±0.1 °C
(±0.2 °F)
(1)
1000 Ω Pt RTD (385)
±0.1 °C
(±0.2 °F)
(1)
100 Ω Pt RTD (3916)
±0.1 °C
(±0.2 °F)
(1)
200 Ω Pt RTD (3916)
±0.1 °C
(±0.2 °F)
(1)
500 Ω Pt RTD (3916)
±0.1 °C
(±0.2 °F)
(1)
1000 Ω Pt RTD (3916)
±0.1 °C
(±0.2 °F)
10 Ω Cu RTD (426)
(1)(2)
±0.2 °C
(±0.4 °F)
120 Ω Ni RTD (618)
(1)(3)
±0.1 °C
(±0.2 °F)
120 Ω Ni RTD (672)
(1)
±0.1 °C
(±0.2 °F)
(1)
604 Ω NiFe RTD (518)
±0.1 °C
(±0.2 °F)
Preliminary Operating Considerations 55
Effective Resolution
The effective resolution for an input channel depends upon the filter
frequency selected for that channel. This table displays the effective
resolution for the various input types and filter frequencies.
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.3 °C
(±0.5 °F)
±0.1 °C
(±0.2 °F)
±0.1 °C
(±0.2 °F)
±0.1 °C
(±0.2 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.3 °C
(±0.5 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.3 °C
(±0.5 °F)
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.3 °C
(±0.5 °F)
±0.1 °C
(±0.2 °F)
±0.1 °C
(±0.2 °F)
±0.1 °C
(±0.2 °F)
±0.4 °C
(±0.7 °F)
±0.4 °C
(±0.7 °F)
±0.4 °C
(±0.7 °F)
±0.4 °C
(±0.7 °F)
±0.3 °C
(±0.5 °F)
±0.3 °C
(±0.5 °F)
±0.3 °C
(±0.5 °F)
±0.3 °C
(±0.5 °F)
±0.4 °C
(±0.7 °F)
±0.2 °C
(±0.4 °F)
±0.3 °C
(±0.5 °F)
±0.2 °C
(±0.4 °F)
150 Ω Resistance Input ±0.02 Ω ±0.04 Ω ±0.04 Ω ±0.08 Ω
500 Ω Resistance Input ±0.1 Ω ±0.2 Ω ±0.2 Ω ±0.4 Ω
1000 Ω Resistance Input ±0.2 Ω ±0.3 Ω ±0.3 Ω ±0.5 Ω
3000 Ω Resistance Input ±0.2 Ω ±0.3 Ω ±0.3 Ω ±0.5 Ω
(1)
The digits following the RTD type represent the temperature coefficient of resistance (µ), which is defined as the resistance change per ohm per °C. For instance,
Platinum 385 refers to a platinum RTD with µ = 0.00385 ohms/ohm - ×C or simply 0.00385 /°C.
(2)
Actual value at 0 °C (32 °F) is 9.042 Ω per SAMA standard RC21-4-1966.
(3)
Actual value at 0 °C (32 °F) is 100 Ω per DIN standard.
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56 Preliminary Operating Considerations
Channel Cut-off Frequency
The channel filter frequency selection determines a channel’s cut-off
frequency, also called the -3 dB frequency. The cut-off frequency is
defined as the point on the input channel frequency response curve
where frequency components of the input signal are passed with 3 dB
of attenuation. All frequency components at or below the cut-off
frequency are passed by the digital filter with less than 3 dB of
attenuation. All frequency components above the cut-off frequency
are increasingly attenuated, as shown in the following figures.
The cut-off frequency for each input channel is defined by its filter
frequency selection. The Notch Frequencies table shows the input
channel cut-off frequency for each filter frequency. Choose a filter
frequency so that your fastest changing signal is below that of the
filter’s cut-off frequency. The cut-off frequency should not be
confused with update time. The cut-off frequency relates how the
digital filter attenuates frequency components of the input signal. The
update time defines the rate at which an input channel is scanned and
its channel data word updated.
See page 58 for determining the channel update time.
10 Hz Filter Notch Frequency
-3 dB
Amplitude (in dB)
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
-200
0 102030405060
2.62 Hz
Frequency
Frequency Response
Hz
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50 Hz Filter Notch Frequency
-3 dB
Amplitude (in dB)
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
-200
0 50 100 150 200 250 300
Preliminary Operating Considerations 57
Hz
13.1 Hz
60 Hz Filter Notch Frequency
-3 dB
Amplitude (in dB)
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
-200
0 60 120 180 240 300
15.72 Hz
250 Hz Filter Notch Frequency
-3 dB
Amplitude (in dB)
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
-200
0 250 500 750 1000 1250 1500
65.5 Hz
Frequency
Frequency Response
Hz
Frequency
Frequency Response
Hz
Frequency
Frequency Response
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58 Preliminary Operating Considerations
Scanning Process and Channel Timing
This section shows how to determine the channel update time and
channel autocalibration time. In addition, the scanning process is
briefly described.
The RTD module channel update time is defined as the time required
for the module to sample and convert (scan) the input signal of an
enabled input channel and make the resulting data value available to
the SLC processor for update.
Channel Autocalibration
Upon entry into the channel enabled state, the corresponding channel
is calibrated and configured according to the channel configuration
word information. Channel calibration takes precedence over channel
scanning and is a function of the selected notch filter.
Channel Calibration Time
Filter Frequency Channel Calibration Time
10 Hz 7300 ms
50 Hz 1540 ms
60 Hz 1300 ms
250 Hz 388 ms
Update Time and Scanning Process
Scanning Cycle on page 60 shows the scanning process for the RTD
module assuming that the module is running normally and more than
one channel is enabled.
The scanning cycle is shown for the situation where channels 0 and 1
are enabled and channels 2 and 3 are not used.
IMPORTANT
The scanning process shown on is similar for any number of
enabled channels.
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Preliminary Operating Considerations 59
Channel scanning is sequential and always occurs starting with the
lowest numbered enabled channel and proceeding to the next highest
numbered channel, for example, channel 0 - channel 1 - channel 2 channel 3 - channel 0 - channel 1. Channel scan time is a function of
the filter frequency.
Channel Scan Time
Filter Frequency
10 Hz 305 ms
50 Hz 65 ms
60 Hz 55 ms
250 Hz 17 ms
(1)
The module-scan time is obtained by summing the channel-scan time for each enabled channel. For example, if
3 channels are enabled and the 50 Hz filter is selected, the module-scan time is 3 X 65 ms = 195 ms.
Channel Scan Time
(1)
The fastest module update time occurs when only one channel with a
250 Hz filter frequency is enabled.
Module Update Time = 17 ms
TIP
With 3 channels enabled, the module update time is: 3
channels_ 17 ms/channel = 51 ms
The slowest module update time occurs when four channels, each
using a 10 Hz filter frequency, are enabled.
Module Update Time = 4 _ 305 ms = 1220 ms
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60 Preliminary Operating Considerations
Configure and start Channel 0 A/D.
Scanning Cycle
Channel 0Channel 1
Start
Update Channel 1 data word.
Calculate Channel 1 data.
Wait for Channel 0 A/D conversion.
Read Channel 1 A/D.
Read Channel 0 A/D.
Wait for Channel 1 A/D conversion.
Configure and start Channel 1 A/D.
Calculate Channel 0 data.
Update Channel 0 data word.
Scan Cycle With Channels 0 and 1 Enabled Only
Publication 1746-UM008B-EN-P - December 2006
Preliminary Operating Considerations 61
Channel Turn-on, Turn-off,
The table below gives you the turn-on, turn-off, and reconfiguration
times for enabling or disabling a channel.
and Reconfiguration Time
Function Description Duration
Turn-on Time The time it takes to make converted data available in the data word and to
set the status bit (transition from 0 to 1) in the status word, after setting the
enable bit in the configuration word.
Turn-off Time The time it takes to reset the status bit (transition from 1 to 0) in the status
word and to zero the data word, after resetting the enable bit in the
configuration word.
Reconfiguration
Time
The time it takes to change a channel configuration if the device type, filter
frequency, or excitation current is different from the current setting. The
enable bit remains in a steady state of 1. (Changing temperature/resistance
units or data format does not require reconfiguration time.)
Requires up to one module update
time plus one of the following:
• 250 Hz Filter = 388 ms
• 60 Hz Filter = 1300 ms
• 50 Hz Filter = 1540 ms
• 10 Hz Filter = 7300 ms
Requires up to one module update
time.
Requires up to one module update
time plus one of the following:
• 250 Hz Filter = 124 ms
• 60 Hz Filter = 504 ms
• 50 Hz Filter = 604 ms
• 10 Hz Filter = 3,004 ms
Response to Slot Disabling
By writing to the status file in your modular SLC processor you can
disable any chassis slot. Refer to your SLC programming manual for
the slot disable/enable procedure.
ATTENTION
Always understand the implications of disabling a RTD module
in your application before using the slot disable feature.
Publication 1746-UM008B-EN-P - December 2006
62 Preliminary Operating Considerations
Input Response
When a RTD slot is disabled, the RTD module continues to update its
input image table. However, the SLC processor does not read inputs
from a module that is disabled. Therefore, when the processor
disables the RTD module slot, the module inputs appearing in the
processor input image remain in their last state and the module’s
updated image table is not read. When the processor re-enables the
module slot, the current state of the module inputs are read by the
processor during the subsequent scan.
Output Response
The SLC processor may change the RTD module output data
(configuration) as it appears in the processor output image. However,
this data is not transferred to the RTD module when the slot is
disabled. The outputs are held in their last state. When the slot is
re-enabled, the data in the processor image is transferred to the RTD
module.
Publication 1746-UM008B-EN-P - December 2006
Chapter
5
Channel Configuration, Data, and Status
This chapter examines the channel configuration word and the
channel status word bit by bit. It explains how the module uses
configuration data and generates status during operation. It gives you
information about how to:
• configure a channel.
• examine channel input data.
• check a channel’s status.
Channel Configuration
The channel configuration word is a part of the RTD module’s output
image. Output words 0…3 correspond to channels 0…3 on the
module. Setting the condition of bits 0…15 in these words via your
ladder logic program causes the channel to operate as you choose (for
example, RTD type or reading in °C). Output words 4…7 are used to
further define the channel configuration to let you choose a scaling
format other than the module default when using the proportional
counts data format. You can use words 4 and 5 to define one user-set
range and words 6 and 7 to define a second range.
A bit-by-bit examination of the configuration word is provided in the
Channel Configuration Word (O:e.0 through O:e.3) - Bit Definitions
table on page 66. Programming is discussed in chapter 6. Addressing
is explained in chapter 4.
Module Output Image (Configuration Word)
O:e.0
O:e.1
O:e.2
O:e.3
CH 0 Configuration Word
CH 1 Configuration Word
CH 2 Configuration Word
CH 3 Configuration Word
015
015
015
015
O:e.4
O:e.5
O:e.6
O:e.7
63 Publication 1746-UM008B-EN-P - December 2006
Defines user±set lower scale limit for range 0
015
Defines user±set upper scale limit for range 0
015
Defines user±set lower scale limit for range 1
015
Defines user±set upper scale limit for range 1
015
64 Channel Configuration, Data, and Status
Module default settings for configuration words 0…7 are all zeros.
Scaling defaults are explained on page 78 under the explanation for
the Scaling Select (Bits 13-14).
The channel configuration word consists of bit fields, the settings of
which determine how the channel operates. This procedure looks at
each bit field separately and helps you configure a channel for
operation.
Refer to the Channel Configuration Word (O:e.0 through O:e.3) - Bit
Definitions table on page 66 and the bit field descriptions that follow
for complete configuration information. Page 128 contains a
configuration worksheet that can assist your channel configuration.
Channel Configuration Procedure
The following sections give you procedures to configure the channels.
Configure Each Channel
1. Determine the input device type (RTD type or resistance input)
for a channel and enter its respective four-digit binary code in
bit field 0…3 (Input Type Selection) of the channel
configuration word.
2. Select a data format for the data word value.
Your selection determines how the analog input value from the
A/D converter is expressed in the data word.
3. Enter your two-digit binary code in bit field 4…5 (Data Format
Selection) of the channel configuration word.
Depending upon how you configure these bit settings, you may
have to select a user-set scaling range.
User-set Scaling Using Proportional Counts Data Format on
page 80 gives an example on how to do this.
Publication 1746-UM008B-EN-P - December 2006
4. Determine the desired state for the channel data word if a
broken input condition is detected for that channel (open circuit
or short circuit).
5. Enter the two-digit binary code in bit field 6 and 7 (Broken Input
Selection) of the channel configuration word.
Channel Configuration, Data, and Status 65
6. If the channel is configured for RTD inputs and engineering
units data format, determine if you want the channel data word
to read in ° C or ° F and enter a one or a zero in bit 8
(Temperature Units) of the configuration word.
If the channel is configured for a resistance input, this field is
ignored.
7. Determine the desired input filter frequency for the channel and
enter the two-digit binary code in bit field 9 and 10 (Filter
Frequency Selection) of the channel configuration word.
A lower filter frequency increases the channel update time, but
also increases the noise rejection and channel resolution. A
higher filter frequency decreases the channel update time, but
also decreases the noise rejection and channel resolution.
8. Place a one in bit 11 (channel Enable) if the channel is used or
place a zero in bit 11 if the channel is not used.
9. Place a zero in bit 12 for an excitation current of 2.0 mA or place
a one in bit 12 for 0.5 mA.
Select the excitation current value based on RTD vendor
recommendations and the Input Specifications table, on
page 118.
10. If you have chosen proportional counts data format, select
whether you want the module-defined default scaling selected
for each channel or if you want to define the scaling range
yourself. Use bits 13 and 14 (user-set scaling) for this setting. If
you choose to define the scaling range for proportional counts
data format, make sure to enter the lower and upper limits in
words 4 and 5 (defines range 0) or 6 and 7 (defines range 1).
11. Place a zero is in bit 15 because this bit is not used.
12. Build the channel configuration word using the configuration
worksheet on page 128 for every channel on each RTD module
repeating the procedures given in steps 1…11.
Enter the Configuration Data
Follow the steps outlined in Chapter 2, Quick Start Guide;
Chapter 6, Ladder Programming Examples; or Appendix D, Channel
Configuration, Data, and Status.
Enter your configuration data into your ladder program and copy it to
the RTD module.
Publication 1746-UM008B-EN-P - December 2006
66 Channel Configuration, Data, and Status
Channel Configuration Word (O:e.0 through O:e.3) - Bit Definitions
Bit(s) Define To select Make these bit settings in the Channel Configuration Word
1514131211109876543210
100 Ω Pt RTD (385)
200 Ω Pt RTD (385)
500 Ω Pt RTD (385)
1000 Ω Pt RTD (385)
100 Ω Pt RTD (3916)
200 Ω Pt RTD (3916)
500 Ω Pt RTD (3916)
0…3 Input type selection
4…5 Data format selection
6…7 Broken input selection
8 Temperature units selection
9…10 Filter frequency selection
11 Channel enable
13…14 Scaling selection
15 Unused
(1)
Actual value at 0 °C (32 °F) is 9.072 Ω per SAMA standard RC21-4-1966.
(2)
Actual value at 0 °C (32 °F) is 100 Ω per DIN standard.
(3)
Values are in 0.1 degree/step or 0.1 Ω/ step for all resistance types, except 150 Ω. For the 150 Ω resistance input type, the values are in 0.01 Ω/step.
(4)
Values are in 1 degree/step or 1 Ω/step for all resistance input types, except 150 Ω. For the 150 Ω resistance input type, the values are in 0.01 Ω/step.
(5)
This bit is ignored when a resistance device is selected.
(6)
Applies to proportional counts data format selected using bits 4 and 5.
(7)
Ensure unused bit 15 is always set to zero.
1000 Ω Pt RTD (3916)
10 Ω Cu RTD (426)
120 Ω Ni RTD (618)
(1)
(2)
120 Ω Ni RTD (672)
604 Ω NiFe RTD (518)
150 Ω Resistance Input
500 Ω Resistance Input
1000 Ω Resistance Input
3000 Ω Resistance Input
Engineering units X 1
Engineering units X 10
(3)
(4)
00
01
Scaled-for-PID 10
proportional counts 11
Set to Zero
00
Set to Upscale 01
Set to Downscale 10
Invalid 11
Degrees C
Degrees F
10 Hz
(5)
(5)
00
0
1
50 Hz 01
60 Hz 10
250 Hz 11
Channel Disabled
0
Channel Enabled 1
Default Scaling 0 0
User-set Scaling (Range 0)
User-set Scaling (Range 1)
Invalid 1 1
(7)
Unused
(6)
(6)
01
10
Not used Not Used Not U
0
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Publication 1746-UM008B-EN-P - December 2006
Channel Configuration, Data, and Status 67
Input Type Selection (Bits 0…3)
The input type bit field lets you configure the channel for the type of
input device you have connected to the module. Valid input devices
are shown in the Channel Configuration Word (O:e.0 through O:e.3) Bit Definitions table.
Data Format Selection (Bits 4 and 5)
The data format bit field lets you define the format for the channel
data word contained in the module input image. Valid data types are
engineering units, scaled-for-PID, and proportional counts. If you
select proportional counts, you have the option of using user-set
scaling bits 13 and 14 (Table Channel Configuration Word (O:e.0
through O:e.3) - Bit Definitions) to define an optimum range for your
application. Unless you specify otherwise, the data will be scaled to
the full scale range for that channel.
Bit Descriptions for Data Format Select
Binary
Value
00 Engineering units x 1 Expresses values in 0.1 ° or 0.1 Ωfor 150 Ω pot.,
01 Engineering units x10 Express values in 1 ° or 1 Ω or 0.1 Ω for 150 Ω pot.
10 Scaled-for-PID The input signal range for the selected input type
11 Proportional counts The input signal range is proportional to your
Select Description
only.
only.
is its full scale input range. The signal range is
scaled into a 0…16,383 range, which is what the
SLC processor expects in the PID function.
selected input type and scaled into a
-32,768…32,767 range (default) or user-set range,
based on the scaling select bits (13 and 14) an
scale limit words (O:e.4/O:e.5 or O:e.6/O:e.7).
Publication 1746-UM008B-EN-P - December 2006
68 Channel Configuration, Data, and Status
Using Scaled-for-PID and Proportional Counts Formats
The RTD module provides eight options for displaying input channel
data. These are 0.1 °F, 0.1 °C, 1 °F, 1 °C, 0.1 Ω, 1 Ω, Scaled-for-PID,
and Proportional Counts. The first six options represent real
engineering units and do not require explanation. The Scaled-for-PID
selection allows you to directly interface RTD Data into a PID
instruction without intermediate scale operations. The Proportional
Counts selection provides the highest display resolution, but also
require you to manually convert the channel data to real Engineering
Units.
Default scaling can be selected for scaled-for-PID data format and
proportional counts data format. User-set scaling can be selected for
proportional counts data format.
For a description of default scaling, see Scaled–for–PID and
Proportional Counts Data Format. For a description of user-set scaling
using proportional counts data format, see page 67.
The equations on page 71 show how to convert from Scaled-for-PID
to Engineering Units, Engineering Units to Scaled-for-PID,
Proportional Counts to Engineering Units, and Engineering Units to
Proportional Counts.
To perform the conversions, you must know the defined temperature
or resistance range for the channel’s input type.
Refer to the Channel Data Word Format in the tables on pages 72…73.
The lowest possible value for an input type is S
possible value is S
HIGH
.
, and the highest
LOW
Scaled–for–PID
If the user selects scaled–for–PID as the data format, the data word for
that channel is a number between 0…16,383. Zero (0) corresponds to
the lowest temperature value of the RTD type or the lowest resistance
value (ohms). The value 16,383 corresponds to the highest
temperature value for that RTD or the highest resistance value (ohms).
For example, if a 100 Ω Platinum RTD (a = 0.003916) is selected, then
the relationship of temperature and module counts is shown in the
following table.
Publication 1746-UM008B-EN-P - December 2006
Relationship Between Temperature and Counts
Temperature Counts
-200 °C (-328 °F) 0
+630 °C (1166 °F) 16383
Channel Configuration, Data, and Status 69
The Linear Relationship Between Temperature and PID Counts graph
shows the linear relationship between output counts and temperature
when one uses scaled–for–PID data format.
Linear Relationship Between Temperature and PID Counts
Counts
16383
±200 °C
630 °C
°C
Proportional Counts Data Format
If the user selects proportional counts data format, the data word for
that channel is a number between -32,768 and 32,767. This provides
the greatest resolution of all scaling options. The value -32,768
corresponds to the lowest temperature value of the RTD type or the
lowest resistance value (ohms). The value 32,767 corresponds to the
highest temperature value for that RTD or the highest resistance value
(ohms). For example, if a 100 Ω Platinum RTD (3916) is selected, then
the relationship of temperature and module counts is shown in the
following table.
Relationship Between Temperature and Counts
Temperature Counts
-200 °C (-328 °F) -32,768
+630 °C (1166 °F) +32,767
The Linear Relationship Between Temperature and Proportional
Counts graph shows the linear relationship between output counts
and temperature when one uses proportional counts data format.
Publication 1746-UM008B-EN-P - December 2006
70 Channel Configuration, Data, and Status
Linear Relationship Between Temperature and Proportional Counts
C
ounts
+ 32,767
±200 °C
630 °C
°C
± 32,768
Publication 1746-UM008B-EN-P - December 2006
Scaled-for-PID to Engineering Units
Channel Configuration, Data, and Status 71
Scaling Examples
The following examples are using the default scaling ranges.
Equation Engr Units Equivalent = S
LOW
+ [(S
HIGH
- S
) x (Scaled-for-PID value displayed / 16383)]
LOW
Assume that the input type is an RTD, Platinum (200Ω, a = 0.00385 °C, range = -200 °C…850 °C),
scaled-for-PID display type. Channel data = 3421.
Want to calculate °C equivalent.
From Channel Data Word Format (Table Data Formats for RTD Temperature Ranges for 0.5 and 2.0 mA
Excitation Current through Table Data Format for 500 Ω Resistance Input), S
= -200 °C and S
LOW
Solution Engr Units Equivalent = -200 °C + [(850 °C - (-200 °C)) x (3421 / 16383)] = 19.25 °C.
Engineering Units to Scaled-for-PID
Equation Scaled-for-PID Equivalent = 16383 x [(Engineering Units desired - S
LOW
) / (S
HIGH
- S
LOW
Assume that the input type is an RTD, Platinum (200 Ω, a = 0.00385 °C, range = -200 °C…850 °C),
scaled-for-PID display type. Desired channel temp. = 344 °C.
Want to calculate Scaled-for-PID equivalent.
From Channel Data Word Format (Table Data Formats for RTD Temperature Ranges for 0.5 and 2.0 mA
Excitation Current through Table Data Format for 500 Ω Resistance Input), S
= -200 °C and S
LOW
Solution Scaled-for-PID Equivalent = 16383 x [(344 °C - (-200 °C)) / (850 °C - (-200 °C))] = 8488.
Proportional Counts to Engineering Units
Equation Engr Units Equivalent = S
LOW
+ {(S
HIGH
- S
) x [(Proportional Counts value displayed + 32768) / 65536]}
LOW
Assume that input type is a potentiometer (1000 Ω, range = 0 to 1000 Ω), proportional counts display type.
Channel data = 21567.
Want to calculate ohms equivalent.
From Channel Data Word Format (Table Data Formats for RTD Temperature Ranges for 0.5 and 2.0 mA
Excitation Current through Table Data Format for 500 Ω Resistance Input), S
= 0 Ω and S
LOW
Solution Engr Units Equivalent = 0 Ω + {[1000Ω - (0 Ω)] x [(21567 + 32768) / 65536]} = 829 Ω.
= 850 °C.
HIGH
)]
= 850 °C.
HIGH
= 1000 Ω
HIGH
Engineering Units to Proportional Counts
Equation Proportional Counts Equivalent = {65536 x [(Engineering Units desired - S
LOW
) / (S
HIGH
- S
LOW
Assume that input type is a potentiometer (3000 Ω, range = 0 to 3000 Ω), proportional counts display type.
Desired channel resistance value = 1809 Ω.
Want to calculate Proportional Counts equivalent.
From Channel Data Word Format (Table Data Formats for RTD Temperature Ranges for 0.5 and 2.0 mA Excitation
Current through Table Data Format for 500 Ω Resistance Input), S
= 0 Ω and S
LOW
HIGH
= 3000 Ω.
Solution Proportional Counts Equivalent = {65536 x [(1809 Ω - (0 Ω)) / (3000 Ω- (0Ω))]} - 32768 = 6750.
Publication 1746-UM008B-EN-P - December 2006
)]} - 32768
72 Channel Configuration, Data, and Status
The Data Formats for RTD Temperature Ranges for 0.5 and 2.0
mA Excitation Current table shows the temperature ranges of
several 1746-NR4 RTDs. The table applies to both 0.5 and 2.0
mA excitation currents. The temperature ranges of the remaining
RTD units vary with excitation current, for example, 1000 Ω
Platinum 385 (table Data Format for 1000 Ω Platinum RTD
(385)), 1000 Ω Platinum 3916 (table Data Format for 1000 Ω
Platinum RTD (3916)) and 10 Ω Copper 426 (table Data Format
for 10 Ω Copper 426 RTD).
Data Formats for RTD Temperature Ranges for 0.5 and 2.0 mA Excitation Current
Data Format
RTD Input Type
100 Ω Platinum (385) -2000…8500 -3280…15,620 -200…850 -328…1562 0 … 16,383 -32,768 … 32,767
200 Ω Platinum (385) -2000…8500 -3280…15,620 -200…850 -328…1562 0 … 16,383 -32,768 … 32,767
500 Ω Platinum (385) -2000…8500 -3280…15,620 -200…850 -328…1562 0 … 16,383 -32,768 … 32,767
100 Ω Platinum (3916) -2000…6300 -3280…11,660 -200…630 -328…1166 0 … 16,383 -32,768 … 32,767
200 Ω Platinum (3916) -2000…6300 -3280…11,660 -200…630 -328…1166 0 … 16,383 -32,768 … 32,767
500 Ω Platinum (3916) -2000…6300 -3280…11,660 -200…630 -328…1166 0 … 16,383 -32,768 … 32,767
120 Ω Nickel (672) -800…2600 -1120…5000 -80…260 -112…500 0 … 16,383 -32,768 … 32,767
120 Ω Nickel (618) -1000…2600 -1480…5000 -100…260 -148…500 0 … 16,383 -32,768 … 32,767
604 Ω Nickel Iron (518) -1000…2000 -1480…3920 -100…200 -148…392 0 … 16,383 -32,768 … 32,767
Data Format for 1000 Ω Platinum RTD (385)
Excitation Current
0.5 mA -2000…8500 -3280…15620 -200…850 -328…1562 0…16,383 -32,768…32,767
Engineering Units x 1 Engineering Units x 10
0.1 °C 0.1 °F 1.0 °C 1.0 °F
Data Format
Engineering Units x 1 Engineering Units x 10
0.1 °C 0.1 °F 1.0 °C 1.0 °F
Scaled-for-PID
Scaled-for-PID
Proportional
Counts (Defaults)
Proportional
Counts (Defaults)
2.0 mA -2000…2400 -3280…4640 -200…240 -328…464 0…16,383 -32,768…32,767
Data Format for 1000 Ω Platinum RTD (3916)
Data Format
Excitation Current
0.5 mA -2000…6300 -3280…11,660 -200…630 -328…1166 0 … 16,383 -32,768…32,767
2.0 mA -2000…2300 -3280…44,600 -200…230 -328…446 0 … 16,383 -32,768…32,767
Publication 1746-UM008B-EN-P - December 2006
Engineering Units x 1 Engineering Units x 10
0.1 °C 0.1 °F 1.0 °C 1.0 °F
Scaled-for-PID
Proportional Counts
(Defaults)
Channel Configuration, Data, and Status 73
Data Format for 10 Ω
(1)
Copper 426 RTD
Data Format
Excitation Current
Engineering Units x 1 Engineering Units x 10
0.1 °C 0.1 °F 1.0 °C 1.0 °F
Scaled-for-PID
Proportional Counts
(Defaults)
0.5 mA not allowed --- --- --- --- --- ---
2.0 mA -1000…2600 -1480…5000 -100…260 -148…500 0…16,383 -32,768…32,767
(1)
Actual value at 0 °C (32 °F) is 9.042 Ω per SAMA standard RC21-4-1966.
The Data Format for 150 Ω Resistance Input table, the Data Format for
500 Ω Resistance Input table and the Data Format for 3000 Ω
Resistance Input table show the resistance ranges provided by the
1746-NR4.
Data Format for 150 Ω Resistance Input
Data Format
Resistance Input Type
Engineering Units x 1 Engineering Units x 10
(1)
0.1 Ω
150 Ω 0…15,000 0…1500 0…16,383 -32,768…32,767
(1)
When ohms are selected, the temperature-units selection (bit 8) is ignored.
1.0 Ω
(1)
Scaled-for-PID
Proportional Counts
(Defaults)
Data Format for 500 Ω Resistance Input
Resistance Input Type
Engineering Units x 1 Engineering Units x 10
(1)
0.1 Ω
500 Ω 0…30,000 0…3000 0…16,383 -32,768…32,767
1000 Ω 0…19,000 0…1900 0…16,383 -32,768…32,767
(1)
When ohms are selected, the temperature-units selection (bit 8) is ignored.
Data Format for 3000 Ω Resistance Input
Excitation Current
Engineering Units x 1 Engineering Units x 10
(1)
0.1 Ω
0.5 mA 0…30,000 0…3000 0…16,383 -32,768…32,767
2.0 mA 0…19,000 0…1900 0…16,383 -32,768…32,767
(1)
When ohms are selected, the temperature-units selection (bit 8) is ignored.
1.0 Ω
1.0 Ω
Data Format
(1)
Data Format
(1)
Scaled-for-PID
Scaled-for-PID
Proportional Counts
(Defaults)
Proportional Counts
(Defaults)
Publication 1746-UM008B-EN-P - December 2006
74 Channel Configuration, Data, and Status
Channel Data Word Resolution for RTDs
The Channel Data Word Resolution for RTDs table shows the data
resolution provided by the 1746-NR4 for RTD input types using the
various data formats.
(1)
Proportional Counts
(Defaults)
RTD Input Type
Engineering Units x 1
Data Format (Bits 4 and 5)
Engineering Units
x 10
Scaled-for-PID
°C °F °C °F °C °F °C °F
100 Ω Platinum 385 0.1 °C/step 0.1 °F/step 1 °C/step 1 °F/step 0.0641 °C/step 0.1154 °F/step 0.0160 °C/step 0.0288 °F/step
200 Ω Platinum 385 0.1 °C/step 0.1 °F/step 1 °C/step 1 °F/step 0.0641 °C/step 0.1154 °F/step 0.0160 °C/step 0.0288 °F/step
500 Ω Platinum 385 0.1 °C/step 0.1 °F/step 1 °C/step 1 °F/step 0.0641 °C/step 0.1154 °F/step 0.0160 °C/step 0.0288 °F/step
1000 Ω Platinum 385 0.1 °C/step 0.1 °F/step 1 °C/step 1 °F/step 0.0641 °C/step 0.1154 °F/step 0.0160 °C/step 0.0288 °F/step
100 Ω Platinum 3916 0.1 °C/step 0.1 °F/step 1 °C/step 1 °F/step 0.0507 °C/step 0.0912 °F/step 0.0127 °C/step 0.0288 °F/step
200 Ω Platinum 3916 0.1 °C/step 0.1 °F/step 1 °C/step 1 °F/step 0.0507 °C/step 0.0912 °F/step 0.0127 °C/step 0.0288 °F/step
500 Ω Platinum 3916 0.1 °C/step 0.1 °F/step 1 °C/step 1 °F/step 0.0507 °C/step 0.0912 °F/step 0.0127 °C/step 0.0288 °F/step
1000 Ω Platinum 3916 0.1 °C/step 0.1 °F/step 1 °C/step 1 °F/step 0.0507 °C/step 0.0912 °F/step 0.0127 °C/step 0.0288 °F/step
10 Ω Copper 426 0.1 °C/step 0.1 °F/step 1 °C/step 1 °F/step 0.0220 °C/step 0.0396 °F/step 0.0051 °C/step 0.0099 °F/step
(2)
120 Ω Nickel 618
0.1 °C/step 0.1 °F/step 1 °C/step 1 °F/step 0.0220 °C/step 0.0396 °F/step 0.0051 °C/step 0.0099 °F/step
120 Ω Nickel 672 0.1 °C/step 0.1 °F/step 1 °C/step 1 °F/step 0.0208 °C/step 0.0374 °F/step 0.0052 °C/step 0.0093 °F/step
604 Ω Nickel Iron 518 0.1 °C/step 0.1 °F/step 1 °C/step 1 °F/step 0.0183 °C/step 0.0330 °F/step 0.0046 °C/step 0.0082 °F/step
(1)
When ohms are selected, the temperature-units selection (bit 8) is ignored. Analog input data is the same for either °C or °F selection.
(2)
Actual value at 0 °C (32 °F) is 100Ω per DIN standard.
The Channel Data Word Resolution for 150 Ω Resistance Input table
and the Channel Data Word Resolution for 500 Ω, 1000 Ω, and 3000
Ω Resistance Inputs table shows the data resolution provided by the
1746-NR4 for resistance input types using the various data formats.
Channel Data Word Resolution for 150 Ω Resistance Input
Data Format (Bits 4 and 5)
Resistance Input Type
Engineering Units x 1 Engineering Units x 10 Scaled-for-PID
Ohms Ohms Ohms Ohms
150 Ω 0.01 Ω / step 0.1 Ω / step 0.0092 Ω / step 0.0023 Ω / step
Publication 1746-UM008B-EN-P - December 2006
Proportional Counts
(Defaults)
Channel Configuration, Data, and Status 75
Channel Data Word Resolution for 500 Ω, 1000 Ω, and 3000 Ω Resistance Inputs
Data Format (Bits 4 and 5)
Resistance Input
Ty pe
500 Ω 0.1 Ω / step 0.1 Ω / step 0.0305 Ω / step 0.0076 Ω / step
1000 Ω 0.1 Ω / step 0.1 Ω / step 0.0610 Ω / step 0.0153 Ω / step
3000 Ω 0.1 Ω / step 0.1 Ω / step 0.1831 Ω / step 0.0458 Ω / step
Engineering Units x 1 Engineering Units x 10 Scaled-for-PID
Ohms Ohms Ohms Ohms
Proportional
Counts (Defaults)
Broken Input Selection (Bits 6 and 7)
The Bit Descriptions for Broken Input Selection table shows the
descriptions for bits 6 and 7. The broken input bit field lets you define
the state of the channel data word when an open-circuit or
short-circuit condition is detected for that channel.
An open-circuit condition occurs when the RTD or potentiometer or
its extension wire is physically separated or opened. This can happen
if the wire is cut or disconnected from the terminal block.
The short-circuit condition applies only to RTD input types. This can
happen if the RTD or its signal wires are shorted together for any
reason. The short-circuit condition does not apply to resistance ranges
since they start at 0 ohms, which can be a short-circuit condition.
Bit Descriptions for Broken Input Selection
Binary
Value
00 zero Force the channel data word to 0 during an open-circuit
01 upscale Force the channel data word value to its full scale during
10 downscale Force the channel data word value to its low scale value
11 not used
Select Description
condition or short-circuit condition.
an open-circuit or short-circuit condition. The full scale
value is determined by the input type, data format, and
scaling selected.
during an open-circuit or short-circuit condition. The low
scale value is determined by the input type, data format,
and scaling selected.
Publication 1746-UM008B-EN-P - December 2006
76 Channel Configuration, Data, and Status
Temperature Units Selection (Bit 8)
The Bit Descriptions for Temperature Units Selection table shows the
description for bit 8. The temperature units bit lets you select
temperature engineering units in °C or °F for RTD input types. This bit
field is only active for RTD input types. It is ignored when the
resistance input type is selected.
Bit Descriptions for Temperature Units Selection
Binary
Value
0 Degrees Celsius Display the channel data word in degrees Celsius
1 Degrees Fahrenheit Display the channel data word in degrees Fahrenheit
Select If you want to
Filter Frequency Selection (Bits 9 and 10)
The Bit Descriptions for Filter Frequency Selection table shows the
descriptions for bits 9 and 10. The channel filter frequency bit field
lets you select one of four filters available for a channel. The filter
frequency affects the channel update time and noise rejection
characteristics (refer to chapter 4 for details).
Bit Descriptions for Filter Frequency Selection
Binary
Value
00 10 Hz Provide both 50 Hz and 60 Hz ac line noise filtering. This setting
Select Description
increases the channel update time, but also increases the noise
rejection.
Publication 1746-UM008B-EN-P - December 2006
01 50 Hz Provide 50 Hz ac line noise filtering.
10 60 Hz Provide 60 Hz ac line noise filtering.
11 250 Hz Provide 250 Hz ac noise filtering. This setting decreases the noise
rejection, but also decreases the channel update time.
Channel Enable Selection (Bit 11)
The Bit Descriptions for Channel Enable Selection table shows the
description for bit 11. You use the channel enable bit to enable a
channel. The RTD module only scans those channels that are enabled.
To optimize module operation and minimize throughput times, you
should disable unused channels by setting the channel enable bit to
zero.
Channel Configuration, Data, and Status 77
When set (1), the channel enable bit is used by the module to read
the configuration word information you have selected. While the
enable bit is set, modification of the configuration word may lengthen
the module update time for one cycle. If any change is made to the
configuration word, the change must be reflected in the status word
before new data is valid.
Refer to Channel Status Checking on page 82.
While the channel enable bit is cleared (0), the channel data word and
status word values are cleared. After the channel enable bit is set, the
channel data word and status word remain cleared until the RTD
module sets the channel status bit (bit 11) in the channel status word.
Bit Descriptions for Channel Enable Selection
Binary
Value
0 Channel disable Disable a channel. Disabling a channel causes the channel
1 Channel enable Enable a channel.
Select Description
data word and the channel status word to be cleared.
Excitation Current Selection (Bit 12)
The Bit Description for Excitation Current Selection table gives the
description for bit 12. Use this bit to select the magnitude of the
excitation current for each enabled channel. Choose from either
2.0 mA or 0.5 mA. This bit field is active for all inputs. A lower current
reduces the error due to RTD self heating, but provides a lower
signal-to-noise ratio. Refer to RTD vendor for recommendations.
See page 119 for general information.
Bit Description for Excitation Current Selection
Binary
Value
Select Description
0 2.0 mA Set the excitation current to 2.0 mA
1 0.5 mA Set the excitation current to 0.5 mA
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78 Channel Configuration, Data, and Status
Scaling Select (Bits 13-14)
If you selected proportional counts as the format for your input data,
you can enter a scaling range that ensures your data is scaled within a
range appropriate for your use. You can use words 4 and 5 to define
one range and words 6 and 7 to define a second range. The Bit
Descriptions for Scaling Selection table gives the descriptions for bits
13 and 14.
Bit Descriptions for Scaling Selection
Binary
Value
00 Use module
01 Use
10 Use
11 not used (configuration error)
Select If you want to
Configure the module to scale the data word using the
defined scaling
configuration
words 4 and 5 for
scaling (range 0)
configuration
words 6 and 7 for
scaling (range 1)
default scale range (-32,768 to 32,767) for scaled-for-PID and
proportional counts.
Define a range (range 0) that your proportional counts data
will be scaled to. Configuration word 4 contains the low
scale limit and configuration word 5 contains the high scale
limit. If you make this setting, be sure to enter low and high
scale values into configuration words 4 and 5.
Define a range (range 1) that your proportional counts data
will be scaled to. Configuration word 6 contains the low
scale limit and configuration 7 contains the high scale limit.
If you make this setting be sure to enter low and high scale
values into configuration words 6 and 7.
Default Scaling
The first case to consider is when default scaling is selected and the
scaling select bits (bits 13 and 14) are set to 00 (module defined
scaling).
Publication 1746-UM008B-EN-P - December 2006
Refer to Scaled–for–PID on page 68 and Proportional Counts Data
Format on page 69 for considerations when using default values.
Channel Configuration, Data, and Status 79
User-set Scaling
Proportional Counts - The second case to consider is User-set Scaling
using proportional counts when the scaling select bits 13 and 14 are
set to 01 or 10. Here you can configure the module to scale the data
word to something other than -32,768 to 32,767. However, the
maximum range remains -32,768 to +32,767. You define what the
upper and lower limits are going to be by placing the range in the
user-set scaling words for range 0 (words 4 and 5) or range 1 (words 6
and 7). The module scales the input data to the upper and lower limit
in an linear relationship. The following example clarifies this feature.
In this example, the RTD module channel that will be configured for
user-set scaling is channel 3.
As shown in User-set Scaling Using Proportional Counts Data Format
on page 80, you have programmed the channel 3 configuration word
for 1000 Ω potentiometer (bits 0…3): proportional counts data format
(bits 4 and 5): and configuration words 4 and 5 for scaling (bits 13 and
14).
The program for the following example is described on page 95 in
Chapter 6.
EXAMPLE
You desire to control the line speed of a conveyor. A
1000 Ω potentiometer is used to sense the conveyor
line speed. The line speed varies between 3
ft/minute (0 Ω) and 50 ft/minute (1000 Ω).
As shown in User-set Scaling Using Proportional
Counts Data Format on page 80, you select a 1000 Ω
potentiometer as the input type.
If you choose engineering units as the data format,
the module data word is a value between 0…1000 Ω.
However, if you choose the proportional counts data
format and utilizes the user-set scaling feature, the
number 3 can be entered in O:e.4 and the number
50 in O:e.5. In this situation, the RTD module returns
a number between 3…50 in its data word. This
action saves you time in ladder programming.
Publication 1746-UM008B-EN-P - December 2006
80 Channel Configuration, Data, and Status
User-set Scaling Using Proportional Counts Data Format
Selected Proportional Counts Data Format
CH 3 Configuration Word
Lower scale limit set for 3
Range 0
Upper scale limit set for 50
Selected Configuration Words 4 & 5 for Scaling
O:e.3
Selected 1000 Ω Pot
110000010100
O:e.4
O:e.5
O:e.6
O:e.7
Defines lower scale limit for range 1
Defines upper scale limit for range 1
Configuration Words For User-set Scaling (Words 4…7)
In the Limit Scale Words example, it shows the address of the user-set
limit scale words used to define the lower value and the upper value
of the user-set scale words. You can use these words when:
• bits 13 and 14 (scaling select) of the channel configuration word
are 01 (Limit Scale 0) and proportional counts mode is selected.
• bits 13 and 14 (scaling select) of the channel configuration word
are 10 (Limit Scale 1) and proportional counts mode is selected.
0111
015
1100000000000000
015
0100110000000000
015
015
015
Range 0
Range 1
These scaling words are global for the module. They are not exclusive
to a particular channel. Be sure the scaling limit range is used on only
compatible channels. Use range 0 or range 1 to apply the appropriate
lower limit word and the upper limit word to any single channel or
channels which are configured for user-set scaling for proportional
counts.
Any time a range is selected, and an invalid combination of scaling
limits is in that range, a configuration error occurs. For example, if
both scaling limits are 0, or if the lower range value is greater than or
equal to the upper range value, a configuration error occurs.
Limit Scale Words
O:e.4
O:e.5
O:e.6
O:e.7
Defines lower scale limit for range 0
Defines upper scale limit for range 0
Defines lower scale limit for range 1
Defines upper scale limit for range 1
015
015
015
015
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Channel Configuration, Data, and Status 81
Unused (Bit 15)
Bit 15 is not used. Verify that this bit is always cleared (0).
The actual RTD or resistance input sensor values reside in I:e.0
through I:e.3 of the RTD module input image file. The data values
present depend on the input type and data format you have selected
in your configuration for the channel. When an input channel is
disabled, its data word is reset (0).
Channel Data Word
Two conditions must be true for the value of the data word shown in
the Module Input Image (Data Word) to be valid.
• The channel must be enabled (channel status bit = 1)
• There must be no channel errors (channel error bit = 0)
Module Input Image (Data Word)
I:e.0
I:e.1
I:e.2
I:e.3
CH 0 Data Word
CH 1 Data Word
CH 2 Data Word
CH 3 Data Word
015
015
015
015
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82 Channel Configuration, Data, and Status
Channel Status Checking
The channel status word is a part of the RTD module’s input image.
Input words 4…7 correspond to and contain the configuration status
of channels 0, 1, 2, and 3 respectively. You can use the data provided
in the status word to determine if the data word for any channel is
valid per your configuration in O:e.0 through O:e.3.
For example, whenever a channel is disabled (O:e.x/11 = 0), its
corresponding status word shows all zeros. This condition tells you
that input data contained in the data word for that channel is not valid
and should be ignored.
Module Input Image (Status Word)
I:e.4
I:e.5
I:e.6
I:e.7
CH 0 Status Word
CH 1 Status Word
CH 2 Status Word
CH 3 Status Word
The channel status word can be analyzed bit by bit. Each bit’s status
(0 or 1) tells you how the input data from the RTD sensor or
resistance device connected to a specific channel is translated for your
application. The bit status also informs you of any error condition and
can tell you what type error occurred.
015
015
015
015
A bit-by-bit examination of the status word is provided in the Channel
0…3 Status Word (I:e.4 through I:e.7) - Bit Definitions table.
Publication 1746-UM008B-EN-P - December 2006
Channel Configuration, Data, and Status 83
Channel 0…3 Status Word (I:e.4 through I:e.7) - Bit Definitions
Bits Define
0…3 Input type status
4…5 Data format status
6…7 Broken input status
8 Temperature units status
9…10 Filter frequency status
11 Channel enable status
12 Excitation current status
13 Broken input error status
14 Out of range error status
15 Configuration error status
(1)
Actual value at 0 °C (32 °F) is 9.042 Ω per SAMA standard RC21-4-1966.
(2)
Actual value at 0 °C (32 °F) is 100 Ω per DIN standard.
(3)
Values are in 0.1 degrees/step or 0.1 Ω/step for all resistance input types, except 150 Ω. For the 150 Ω, resistance input type, the values are in 0.01 Ω/step.
(4)
Values are in 1 degree /step or 1 Ω/step for all resistance input types, except 150 Ω. For the 150 Ω, resistance input type, the values are in 0.1 Ω/step.
(5)
This bit is cleared (0) when a resistance device, such as a potentiometer, is selected.
These bit settings
1514131211109876543210
Indicate this
0000 100 Ω Pt RTD (385)
0001 200 Ω Pt RTD (385)
0010 500 Ω Pt RTD (385)
0011 1000 Ω Pt RTD (385)
0100 100 Ω Pt RTD (3916)
0101 200 Ω Pt RTD (3916)
0110 500 Ω Pt RTD (3916)
0111 1000 Ω Pt RTD (3916)
1000
1001
1010 120 Ω Ni RTD (672)
1011 604 Ω NiFe RTD (518)
1100 150 Ω Resistance Input
1110 1000 Ω Resistance Input
1111 3000 Ω Resistance Input
00
01
Engineering units X 1
Engineering units X 10
10 Scaled-for-PID
11 Proportional Counts
00 Set to Zero
01 Set to Upscale
10 Set to Downscale
11 Not used
0
1
00 10 Hz
01 50 Hz
10 60 Hz
11 250 Hz
0 Channel Disabled
1 Channel Enabled
0 2.0 mA
1 0.5 mA
0 No error
1 Short or opened detected
0 No error
1 Out of range detected
0
1
10 Ω Cu RTD (426)
120 Ω Ni RTD (618)
Degrees °C
Degrees °F
(5)
(5)
No error
Configuration error
(1)
(2)
(3)
(4)
Publication 1746-UM008B-EN-P - December 2006
84 Channel Configuration, Data, and Status
IMPORTANT
The status bits reflect the settings that were made in the configuration
word. However, two conditions must be true if the status reflected is to
be accurate.
• The channel must be enabled.
• The channel must have processed any new configuration data.
Input Type Status (Bits 0…3)
The input type bit field indicates what type of input device you have
configured for the channel. This field reflects the input type selected
in bits 0…3 of the channel configuration word when the channel is
enabled. If the channel is disabled, these bits are cleared (0).
Data Format Status (Bits 4 and 5)
The data format bit field indicates the data format you have defined
for the channel. This field reflects the data type selected in bits 4 and
5 of the channel configuration word when the channel is enabled. If
the channel is disabled, these bits are cleared (0).
Publication 1746-UM008B-EN-P - December 2006
Broken Input Status (Bits 6 and 7)
The broken input bit field indicates how you have defined the
channel data to respond to an open-circuit or short-circuit condition.
This field reflects the broken input type selected in bits 6 and 7 of the
channel configuration word when the channel is enabled. If the
channel is disabled, these bits are cleared (0).
Temperature Units Status (Bit 8)
The temperature units field indicates the state of the temperature units
bit in the configuration word (bit 8). This feature is only active for
RTD input types with the channel enabled. This bit is cleared (0) if the
channel is disabled or if the input type is a resistance device such as
potentiometer.
Channel Configuration, Data, and Status 85
Channel Filter Frequency (Bits 9 and 10)
The channel filter frequency bit field reflects the filter frequency you
selected in bits 9…10 of the configuration word when the channel is
enabled. This feature is active for all input types. If the channel is
disabled, these bits are cleared (0).
Channel Enable Status (Bit 11)
The channel enable status bit indicates whether the channel is
enabled or disabled. This bit is set (1) when the channel enable bit is
set in the configuration word (bit 11) and there is valid data in the
channel’s data word. The channel status bit is cleared (0) if the
channel is disabled.
Excitation Current (Bit 12)
This bit indicates the excitation current setting made to bit 12 of the
channel’s configuration word when the channel is enabled. If the
channel is disabled, this bit is cleared (0).
Broken Input Error (Bit 13)
This bit is set (1) whenever an enabled channel detects a broken input
condition. A broken input error is declared for reasons that include:
• open-circuit - excitation current is less than 50% of the selected
current.
• short-circuit - calculated lead wire compensated RTD resistance
is less than 3 Ω.
The open-circuit error is active for all RTD and resistance inputs,
while the short-circuit error is valid only for RTD inputs. If a broken
input is detected, the module sends either zero, upscale, or downscale
data to the channel data word for that channel, depending on your
channel configuration bits 6 and 7.
A broken input error takes precedence over an out-of-range error
states. There will not be an out-of-range error when an open-circuit or
short circuit is detected.
This bit is cleared if the channel is disabled or if the channel operation
is normal.
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86 Channel Configuration, Data, and Status
Out-of-range Error (Bit 14)
This bit is set (1) whenever a configured channel detects an
over-range condition for the input channel data, regardless of input
type. This bit is also set (1) whenever the module detects an
under-range condition when the input type is an RTD. An
out-of-range error is declared for either of the following conditions:
• over-range - The RTD temperature is greater than the maximum
allowed (default or user-set) temperature or the resistance input
type is greater than the maximum allowed (default or user-set)
resistance. When this occurs, the channel data word is set to its
maximum value.
• under-range - The RTD temperature is less than the minimum
allowed (default or user-set) temperature. When this occurs, the
channel data word is set to its minimum value.
IMPORTANT
This bit is cleared (0) when the:
• channel is disabled.
• channel operation is normal, the out-of-range condition clears.
• broken input error bit (bit 13) is set (1).
There is no under-range error for a direct resistance input
(default scaling).
Configuration Error (Bit 15)
This bit is set (1) whenever an enabled and configured channel
detects that the channel configuration word is not valid. A
configuration word is not valid for any of the these reasons.
• Input type is a 10 Ω Copper RTD and the excitation current is set
for 0.5 mA, which is not allowed.
• Scaling select bits 13 and 14 are set to 11, which is invalid.
• Broken Input select bits 6 and 7 are set to 11, which is invalid.
• Scaling select bits 13 and 14 are set to 01 or 10 and scaling limit
words=0.
• Data format bits are set to 11, the scaling-select bits are set to 01
or 10 and the lower limit user-set scale word is greater than or
equal to the upper limit user-set scale word.
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All other status bits reflect the settings from the configuration word
(even those settings that may be in error). However, bit 15 is cleared if
the channel is disabled or if channel operation is normal.
Chapter
6
Ladder Programming Examples
Earlier chapters explained how the configuration word defines the
way a channel operates. This chapter shows the programming
required to enter the configuration word into the processor memory.
It also provides you with segments of ladder logic specific to unique
situations that might apply to your programming requirements. The
example segments include:
• initial programming of the configuration word.
• dynamic programming of the configuration word.
• verifying channel configuration changes.
• interfacing the RTD module to a PID instruction.
• using proportional counts scaling (example).
• monitoring channel status bits.
• invoking autocalibration.
Device Configuration
The Application Setup diagram is used for clarification of the ensuing
ladder logic examples and is not intended to represent an RTD
application.
IMPORTANT
Chapter 8 shows a typical application for the RTD module.
87 Publication 1746-UM008B-EN-P - December 2006
88 Ladder Programming Examples
1746-OB8 DC Output Module (Sourcing)
1746-IB8 DC Input Module (Sinking)
SLC Processor
Application Setup
1746-NR4 RTD Module
12 30
Slot #
RTD 0
RTD 1
RTD 2
Pilot Light O:2/1
Pilot Light O:2/0
Pushbutton Switch I:1/1
Initial Programming
RTD 3
Pilot Light O:2/3
Ch. 0 Alarm
Autocalibration
Ch. 1 Alarm Ch. 2 Alarm Ch. 3 Alarm
F8
Display Panel
°C
Pilot Light O:2/2
°F
Selector Switch I:1/0
Follow this example to enter data into the channel configuration word
(O:e.0 through O:e.3) when the channel is disabled (bit 11 = 0).
Refer to the Channel Configuration Word (O:e.0 through O:e.3) - Bit
Definitions table for specific configuration details.
EXAMPLE
As shown in the Configuration Word Setup diagram, configure
four channels of a RTD module residing in slot 3 of a 1746
chassis. Configure each channel with the same parameters.
Publication 1746-UM008B-EN-P - December 2006
Configuration Word Setup
A
Ladder Programming Examples 89
1112131415
0010000
910 8
67
1
00 01450001
0123
Bit Number
Bit Setting
Configures Channel For:
200 Ω Platinum RTD (385)
Eng. Units x 10 (1 °F/ step)
Broken Input (Zero Data Word)
Degrees Fahrenheit (°F)
10 Hz Filter Frequency
Channel Enabled
2.0 mA Excitation Current
Default Scaling
Not Used
This example transfers configuration data and sets the channel enable
bits of all four channels with a single file copy instruction. The file
copy instruction copies four data words from an integer file you create
in the SLC controller’s memory, to the RTD module’s channel
configuration words.
Copy File Data Flow
DDRESS
N10:0
N10:1
N10:2
N10:3
SOURCE DATA FILE
Channel Configuration Word 0
Channel Configuration Word 1
Channel Configuration Word 2
Channel Configuration Word 3
ADDRESS
O:3.0
O:3.1
O:3.2
O:3.3
DESTINATION DATA FILE
Channel Output Word 0
Channel Output Word 1
Channel Output Word 2
Channel Output Word 3
Publication 1746-UM008B-EN-P - December 2006
90 Ladder Programming Examples
Programming Procedure
1. Create integer file N10 in your programming software.
Integer file N10 should contain four elements (N10:0 through
N10:3).
2. Enter the configuration parameters for all four RTD channels
into a source integer data file N10.
Refer to the Configuration Word Setup for the bit values.
See page 128 for a channel configuration worksheet.
3. Program this rung to use the copy file instruction (COP) to copy
the contents of integer file N10 to the four consecutive output
words of the RTD module beginning with O:3.0.
All elements are copied from the specified source file to the
destination during the first scan after applying power to the
module.
In
First Pass Bit
S:1
] [
15
itialize RTD module
COP
COPY FILE
Source #N10:0
Dest #O:3.0
Length 4
Publication 1746-UM008B-EN-P - December 2006
Ladder Programming Examples 91
Dynamic Programming
The programming example explains how to change data in the
channel configuration word when the channel is currently enabled.
EXAMPLE
Execute a dynamic configuration change to channel 2 of the
RTD module located in slot 3 of a 1746 chassis. Change from
monitoring the temperature in °F to monitoring in °C.
Programming Procedure
1. Create a new element in integer file N10 using the memory map
function.
Integer file N10 already contains four elements (N10:0 through
N10:3). You add a fifth element (N10:4).
2. Enter the same configuration data as in the previous example
using the data monitor function, except for bit 8.
Bit 8 is now set for a logic 0 (°C).
Rung 2:1
Rung 2:2
Rung 2:3
Set up all four channels.Rung 2:0
S:1
] [
15
Set channel 2 to display in ˚C.
I:1.0
] [
Set channel 2 back to display in ˚F
I:1.0
]/[
0
0
B3
[OSR]
B3
[OSR]
0
1
COP
COPY FILE
Source #N10:0
Dest #O:3.0
Length 4
MOV
MOVE
Source N10:4
Dest O:3.2
MOV
MOVE
Source N10:2
Dest O:3.2
END
Publication 1746-UM008B-EN-P - December 2006
92 Ladder Programming Examples
Verify Channel Configuration Changes
When executing a dynamic channel configuration change, there is
always a delay from the time the ladder program makes the change to
the time the RTD module gives you a data word using that new
configuration information. Therefore, it is very important to verify that
a dynamic channel configuration change took effect in the RTD
module. This is particularly important if the channel being
dynamically configured is used for control. The Program to Verify
Configuration Word Data Changes ladder diagram explains how to
verify that channel configuration changes have taken effect.
EXAMPLE
Execute a dynamic configuration change to channel 2 of the
RTD module located in slot 3 of a 1746 chassis, and set an
internal data valid bit when the new configuration has taken
effect.
Program to Verify Configuration Word Data Changes
Set up all four channels.Rung 2:0
COP
COPY FILE
Source #N10:0
Dest #O:3.0
Length 4
MOV
MOVE
Source N10:4
Dest O:3.2
Rung 2:1
S:1
] [
15
Set channel 2 to display in ˚C.
I:1.0
] [
0
B3
[OSR]
0
Rung 2:2
Rung 2:3
Publication 1746-UM008B-EN-P - December 2006
Set channel 2 back to display in ˚F.
I:1.0
]/[
0
B3
[OSR]
1
MOV
MOVE
Source N10:2
Dest O:3.2
MVM
MASKED MOVE
Source I:3.6
Mask 9FFF
Dest N7:0
XOR
BITWISE EXCLUS OR
Source A N7:0
Mask O:3.2
Dest N7:1
Ladder Programming Examples 93
Program to Verify Configuration Word Data Changes - Continued
Rung 2:4
Rung 2:5
Check that the configuration written to channel 2 is
being echoed back in channel 2's status word.
EQU
EQUAL
Source A N7:1
Source B 0
END
Data valid
B3
( )
3
Interface to the PID Instruction
The RTD module was designed to interface directly to the SLC 5/02,
SLC 5/03, SLC 5/04, and SLC 5/05 PID instruction without the need for
an intermediate scale operation. Use RTD channel data as the process
variable in the PID instruction.
Use this procedure to program this application.
1. Select 100 Ω Platinum RTD, ∝ = 0.003916, as the input type by
setting bit 0 = 0, bit 1 = 0, bit 2 = 1, and bit 3 = 0 in the
configuration word.
2. Select scaled-for-PID as the data type by setting bit 4 = 0 and bit
5 = 1 in the configuration word.
ATTENTION
When using the module’s scaled-for-PID data format with the
SLC PID function, verify that the PID instruction parameters
Maximum Scaled S
(word 8) and Minimum Scaled S
max
min
(word 8) match the module’s minimum and maximum scaled
range in engineering units, (-200…850 °C, (-328…1562 °F)) for
that channel. This allows you to accurately enter the setpoint in
engineering units (°C, °F).
Publication 1746-UM008B-EN-P - December 2006
94 Ladder Programming Examples
Rung 2:0
First Pass Bit
S:1
] [
15
Rung 2:1 Channel 0
Status
I:3.4
] [
11
The Rate and Offset parameters should be set per your application. The Dest is typically an analog output
Rung 2:2
channel. Refer to the SLC Instruction Set Reference Manual or Analog I/O Modules User Manual for specific
examples of the SCL instruction
Initialize NR4 Channel 0
MOV
MOVE
Source N10:0
Dest O:3.0
Entering address N1 1:0 allocates elements N11:0 to N11:22 for required
Control Block file length of 23 words. The Process Variable is address
I:3.0, which stores the value of input data word 0 (channel 0). Output of
the PID instruction is stored at address N11:23 (Control Variable
address).
PID
PID
Control Block N11:0
Process Variable I:3.0
Control Variable N11:23
Control Block Length 23
SCL
SCALE
Source N11:23
Rate [/10000]
Rung 2:3
Offset
Dest
END
Publication 1746-UM008B-EN-P - December 2006
Ladder Programming Examples 95
Use the Proportional Counts Data Format with User-set Scaling
The RTD module can be set up to return data to the user program that
is specific to the application. Assume that you control the line speed
of a conveyor using a 1000 Ω potentiometer connected to channel 0 of
the RTD module. The line speed will vary between 3 ft/m when the
potentiometer is at 0 Ω and 50 ft/m when the potentiometer is at 1000
Ω.
Follow these procedures to configure the RTD module to return a
value between 3…50 in the data word for channel 0.
1. Set bits 0…3 of configuration word 0…1110 to select the 1000 Ω
potentiometer input type.
2. Set bits 4 and 5 of configuration word 0…11 to select
proportional counts data format.
3. Set bits 13 and 14 of configuration word 0…01 to select range 0
as the scaling range.
4. Enter 3 as the low range into N10:4.
5. Enter 50 as the high range into N10:5.
Six elements are copied from the
specified source address (N10:0) to the
specified output (O:30:0). Each element
is a 16-bit integer as shown in the data
table at the bottom of the page.
The Source of this instruction is the
data word from the RTD module, which
is a number between 3…50. The Dest
in this application is an analog output
channel controlling the speed of the
conveyor motor drive. The Rate and
Offset parameters should be set per
your application. Refer to the SLC 500
Instruction Set Reference Manual,
publication 1747-RM001, or the Analog
I/O User Manual, publication
1746-UM005, for specific examples of
the SCL instruction.
Rung 2:0
Rung 2:1
Rung 2:2
First Pass Bit
S:1
] [
15
I:3.4
] [
11
Initialize RTD module.
COP
COPY FILE
Source #N10:0
Dest #O:3.0
Length 6
Set speed of conveyor motorChannel 0 Status
SCL
SCALE
Source I:3.0
Rate [/10000]
Offset
Dest
END
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96 Ladder Programming Examples
Monitor Channel Status Bits
The Programming to Monitor Channel Status ladder diagram shows
how you could monitor the open- and short-circuit error bits of each
channel and set an alarm in the processor if one of the RTDs or
resistance-input devices (such as a potentiometer) opens or shorts. An
open-circuit error can occur if the RTD or resistance-input device
breaks or one of the RTD or resistance-input device wires get cut or
disconnected from the terminal block. A short-circuit condition
applies only to RTD input.
Programming to Monitor Channel Status
Rung 2:0
Rung 2:1 Channel 0
Rung 2:2 Channel 1
First Pass Bit
S:1
] [
15
Status
I:3.4
] [
11
Status
I:3.5
] [ ] [
11
Channel 0
Open or Short
I:3.4
] [
13
Channel 1
Open or Short
I:3.5
13
Initialize RTD module.
COP
COPY FILE
Source #N10:0
Dest #O:3.0
Length 4
Channel 0
Alarm
O:2.0
( )
0
Channel 1
Alarm
O:2.0
( )
1
Rung 2:3 Channel 2
Status
I:3.6 I:3.6
11
Rung 2:4 Channel 3
Status
I:3.7
] [
11
Rung 2:5
Channel 2
Open or Short
] [] [
13
Channel 3
Open or Short
I:3.7
] [
13
Channel 2
Alarm
O:2.0
( )
2
Channel 3
Alarm
O:2.0
( )
3
END
Publication 1746-UM008B-EN-P - December 2006
Ladder Programming Examples 97
Invoke Autocalibration
Autocalibration of a channel occurs whenever:
• a channel first becomes enabled.
• when a change is made to its input type, filter frequency, or
excitation current.
• whenever an operating channel is disabled and re-enabled using
its enable bit.
Referring to Programming to Monitor Channel Status on page 96, you
can command your module to perform an autocalibration cycle by
disabling a channel, waiting for the status bit to change state (1…0),
and then re-enabling that channel.
TIP
To maintain system accuracy we recommend that you
periodically perform an autocalibration cycle at these times.
• Whenever an event occurs that greatly changes the internal
temperature of the control cabinet, such as opening or closing its
door
• At a convenient time when the system is not making product, such
as during a shift change.
ATTENTION
Several channel cycles are required to perform an
autocalibration and it is important to remember that during
autocalibration the module is not converting input data.
This ladder diagram show you how to command the RTD module to
perform an autocalibration of channel 0. The RTD module is in slot 3.
Publication 1746-UM008B-EN-P - December 2006
98 Ladder Programming Examples
Programming to Invoke Autocalibration
Rung 2:0 Channel 0 Enable
Rung 2:1 Channel 0 Enable
Condition for
Autocalibration
I:1
] [
1
Channel 0 Status
I:3.4
]/[
11
B3
[OSR]
0
Channel 0 Flag
B3
] [
1
O:3.0
(U)
11
Channel 0 Flag
B3
(L)
1
O:3.0
(L)
11
Channel 0 Flag
B3
(U)
1
IMPORTANT
The RTD module responds to processor commands much more
frequently than it updates its own LED indicators. Therefore, it
is normal to execute these two rungs and have the RTD module
perform an autocalibration of channel 0 without the channel 0
LED indicator ever changing state.
Publication 1746-UM008B-EN-P - December 2006
Chapter
Module Diagnostics and Troubleshooting
7
Introduction
Module Operation vs. Channel Operation
This chapter describes troubleshooting using the channel status LED
indicators as well as the module status LED indicator.
A troubleshooting flowchart is shown on page 105.
The flowchart explains the types of conditions that might cause an
error to be reported and gives suggestions on how to resolve the
problem. Major topics include the following:
• Module operation vs. channel operation
• Power-up diagnostics
• Channel diagnostics
• LED indicators
• Troubleshooting flowchart
• Replacement parts
• Contacting Rockwell Automation
The RTD module performs operations at two levels.
• Module-level operations
• Channel-level operations
Module-level operations include functions such as power up
configuration and communication with the SLC processor.
Channel-level operations describe channel-related functions, such as
data conversion and open-circuit or short-circuit (RTD units only)
detection.
Internal diagnostics are performed at both levels of operation and any
error conditions detected are immediately indicated by the module’s
LED indicators and status to the SLC processor.
99 Publication 1746-UM008B-EN-P - December 2006
100 Module Diagnostics and Troubleshooting
A series of internal diagnostic self-tests is performed when power is
applied to the module. The module status LED indicator and all
channel status LED indicators remain off while power is applied. If
any diagnostic test fails, the module enters the module error state. If
all tests pass, the module status LED indicator is turned on and the
channel status LED indicator is turned on for the respective enabled
channel. The module continuously scans all enabled channels and
communicates with the SLC processor. During power up, the RTD
module does not communicate with the processor.
Power Turn-on Diagnostics
Channel Diagnostics
LED Indicators
When a channel is enabled (bit 11 = 1), a diagnostic check is
performed to see that the channel has been properly configured. In
addition, the channel is tested for out-of-range, open-circuit, and short
circuit faults on every scan.
A failure of any channel diagnostic test causes the faulted channel
status LED indicator to blink. All channel faults are indicated in bits
13…15 of the channel’s status word. Channel faults are self-clearing
(bits 13 and 14 of status word). Bit 15 is not cleared until the you
make the correct change to the channel configuration. The channel
LED indicator stops blinking and resumes steady illumination when
the fault conditions are corrected.
IMPORTANT
If you clear (0) a channel enable bit (11), all channel status
information (including error information) is reset (0).
The RTD module has five LED indicators. Four of these are channel
status LED indicators numbered to correspond to each of the
RTD/resistance input channels, and one is a module status LED
indicator.
Publication 1746-UM008B-EN-P - December 2006
LED Indicator Display
CHANNEL
STATUS
MODULE STATUS
RTD/resistance
INPUT
012
Channel LED Indicators
3
Module Status LED Indicator
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