Rockwell Automation 1746-NT4 User Manual

SLC™ 500 4-Channel Thermocouple/mV Input Module

(Catalog Number 1746-NT4,

Series B)

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://www.ab.com/manuals/gi) 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 we use notes to make you aware of safety
	considerations.
							Identifies information about practices or circumstances
	WARNING
							that can cause an explosion in a hazardous environment,
							which may lead to personal injury or death, property
							damage, or economic loss.
							Identifies information that is critical for successful
	IMPORTANT
							application and understanding of the product.
							Identifies information about practices or circumstances
	ATTENTION
							that can lead to personal injury or death, property
							damage, or economic loss. Attentions help you:
							• identify a hazard
							• avoid a hazard
							• recognize the consequence
							Labels may be located on or inside the drive to alert
	SHOCK HAZARD
							people that dangerous voltage may be present.

BURN HAZARD	Labels may be located on or inside the drive to alert
	people that surfaces may be dangerous temperatures.

Summary of Changes

The information below summarizes the changes to this manual since the last printing.

To help you find new and updated information in this release of the manual, we have included change bars as shown to the right of this paragraph.

For information on:	See page:
Changes to the SLC™ 500 Thermocouple/mV Input Module.	throughout manual
Using RSLogix™ 500 to configure the NT4 module.	2-4, 5-2, 6-1, and Appendix
	E
Maintaining the ambient temperature surrounding the SLC	A-2
500 above 3°C (37.4°F).

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2 Summary of Changes

Publication 1746-UM007C-EN-P - July 2004

Table of Contents

Preface

	Who Should Use this Manual. . . . . . . . . . . . . . . . . . . . . . .	P-1
	Purpose of this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . .	P-1
	Related Documentation . . . . . . . . . . . . . . . . . . . . . . . .	P-2
	Your Questions or Comments on this Manual . . . . . . . .	P-3
	Common Techniques Used in this Manual . . . . . . . . . . . . .	P-3
	Chapter 1
Overview	General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	1-1
	Hardware Features. . . . . . . . . . . . . . . . . . . . . . . . . . . .	1-2
	General Diagnostic Features . . . . . . . . . . . . . . . . . . . . .	1-3
	System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	1-3
	System Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . .	1-4
	Module Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . .	1-5
	Thermocouple Compatibility . . . . . . . . . . . . . . . . . . . .	1-5
	Linear Millivolt Device Compatibility. . . . . . . . . . . . . . .	1-7
	Chapter 2
Quick Start for Experienced Users	Required Tools and Equipment . . . . . . . . . . . . . . . . . . . . .	2-1
	Installation Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . .	2-2
	Chapter 3
Installation and Wiring	Compliance to European Union Directives . . . . . . . . . . . . .	3-1
	EMC Directive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	3-1
	Electrostatic Discharge. . . . . . . . . . . . . . . . . . . . . . . . . . . .	3-2
	NT4 Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . .	3-2
	Module Location in Chassis . . . . . . . . . . . . . . . . . . . . . . . .	3-3
	Fixed Expansion Chassis Considerations . . . . . . . . . . . .	3-3
	General Considerations . . . . . . . . . . . . . . . . . . . . . . . .	3-5
	Module Installation and Removal . . . . . . . . . . . . . . . . . . . .	3-5
	Terminal Block Removal . . . . . . . . . . . . . . . . . . . . . . .	3-6
	Module Installation Procedure . . . . . . . . . . . . . . . . . . .	3-6
	Module Removal Procedure . . . . . . . . . . . . . . . . . . . . .	3-7
	Terminal Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	3-7
	Wiring Considerations . . . . . . . . . . . . . . . . . . . . . . . . .	3-8
	Wiring Input Devices to the NT4 . . . . . . . . . . . . . . . . .	3-11
	Cold Junction Compensation (CJC) . . . . . . . . . . . . . . . .	3-12
	Thermocouple Calibration . . . . . . . . . . . . . . . . . . . . . . . . .	3-13
	Chapter 4
Preliminary Operating	Module ID Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	4-1
Considerations	Module Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	4-2
	Output Image-Configuration Words . . . . . . . . . . . . . . .	4-2
	Input Image-Data Words and Status Words . . . . . . . . . .	4-3
	Channel Filter Frequency Selection . . . . . . . . . . . . . . . . . .	4-4

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Table of Contents	ii

Channel Configuration, Data, and

Status

Ladder Programming Examples

Effective Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4 Channel Cut-Off Frequency . . . . . . . . . . . . . . . . . . . . . 4-5 Channel Step Response . . . . . . . . . . . . . . . . . . . . . . . . 4-6 Update Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7 Update Time Calculation Example . . . . . . . . . . . . . . . . 4-8 Channel Turn-On, Turn-Off, and Reconfiguration Times . . . 4-9 Response to Slot Disabling . . . . . . . . . . . . . . . . . . . . . . . . 4-10 Input Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10 Output Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10

Chapter 5

Channel Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 Channel Configuration Procedure . . . . . . . . . . . . . . . . . . . 5-2 Select Input Type (Bits 0-3) . . . . . . . . . . . . . . . . . . . . . 5-5 Select Data Format (Bits 4 and 5) . . . . . . . . . . . . . . . . . 5-5 Using Scaled-for-PID and Proportional Counts . . . . . . . 5-6 Scaling Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7 Select Open Circuit State (Bits 6 and 7). . . . . . . . . . . . . 5-10 Select Temperature Units (Bit 8) . . . . . . . . . . . . . . . . . . 5-11 Select Channel Filter Frequency (Bits 9 and 10). . . . . . . 5-11 Select Channel Enable (Bit 11) . . . . . . . . . . . . . . . . . . . 5-12 Unused Bits (Bits 12-15). . . . . . . . . . . . . . . . . . . . . . . . 5-12 Channel Data Word. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12 Channel Status Checking . . . . . . . . . . . . . . . . . . . . . . . . . . 5-13 Status Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-15 Input Type Status (Bits 0-3) . . . . . . . . . . . . . . . . . . . . . 5-15 Data Format Type Status (Bits 4 and 5) . . . . . . . . . . . . . 5-15 Open Circuit Type Status (Bits 6 and 7) . . . . . . . . . . . . 5-15 Temperature Units Type Status (Bit 8). . . . . . . . . . . . . . 5-16 Channel Filter Frequency (Bits 9 and 10) . . . . . . . . . . . 5-16 Channel Status (Bit 11). . . . . . . . . . . . . . . . . . . . . . . . . 5-16 Open-Circuit Error (Bit 12) . . . . . . . . . . . . . . . . . . . . . . 5-16 Under-Range Error (Bit 13). . . . . . . . . . . . . . . . . . . . . . 5-16 Over-Range Error (Bit 14). . . . . . . . . . . . . . . . . . . . . . . 5-17 Configuration Error (Bit 15) . . . . . . . . . . . . . . . . . . . . . 5-17

Chapter 6

Initial Programming. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2 Dynamic Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3 Verifying Channel Configuration Changes . . . . . . . . . . . . . 6-4 Interfacing to the PID Instruction. . . . . . . . . . . . . . . . . . . . 6-5 Monitoring Channel Status Bits . . . . . . . . . . . . . . . . . . . . . 6-6 Invoking Autocalibration . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7

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Table of Contents iii

Chapter 7

Module Diagnostics and	Module Operation vs Channel Operation . . . . . . . . . . . . . .	7-1
Troubleshooting	Power-up Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . .	7-1
	Channel Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	7-2
	LED Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	7-3
	Channel Status LEDs (Green) . . . . . . . . . . . . . . . . . . . .	7-4
	Invalid Channel Configuration . . . . . . . . . . . . . . . . . . .	7-4
	Open Circuit Detection . . . . . . . . . . . . . . . . . . . . . . . .	7-4
	Out-Of-Range Detection. . . . . . . . . . . . . . . . . . . . . . . .	7-5
	Module Status LED (Green) . . . . . . . . . . . . . . . . . . . . .	7-5
	Troubleshooting Flowchart . . . . . . . . . . . . . . . . . . . . . . . .	7-6
	Replacement Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	7-7
	Contacting Rockwell Automation . . . . . . . . . . . . . . . . . . . .	7-7
	Chapter 8
Application Examples	Basic Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	8-1
	Application Setup (Display a Temperature) . . . . . . . . .	8-1
	Channel Configuration . . . . . . . . . . . . . . . . . . . . . . . . .	8-2
	Supplementary Example . . . . . . . . . . . . . . . . . . . . . . . . . .	8-4
	Application Setup (Four Channels °C - °F) . . . . . . . . . .	8-4
	Device Configuration . . . . . . . . . . . . . . . . . . . . . . . . . .	8-4
	Channel Configuration . . . . . . . . . . . . . . . . . . . . . . . . .	8-5
	Program Setup and Operation Summary . . . . . . . . . . . .	8-7
	Program Listing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	8-7
	Appendix A
Specifications	Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . .	A-1
	Physical Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . .	A-2
	Environmental Specifications . . . . . . . . . . . . . . . . . . . . . . .	A-2
	Input Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	A-3
	1746-NT4 Module Accuracy . . . . . . . . . . . . . . . . . . . . .	A-4
	Input Resolution per Thermocouple Type at Each Filter
	Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	A-4
	Appendix B
NT4 Configuration Worksheet	Channel Configuration Procedure . . . . . . . . . . . . . . . . . . .	B-1
	Channel Configuration Worksheet . . . . . . . . . . . . . . . . . . .	B-4
	Appendix C
Thermocouple Restrictions	J Type Thermocouple . . . . . . . . . . . . . . . . . . . . . . . . . . . .	C-1
	(Iron vs. Copper-Nickel <Constantan>) . . . . . . . . . . . . .	C-1
	K Type Thermocouple . . . . . . . . . . . . . . . . . . . . . . . . . . .	C-2
	(NIckel-Chromium vs. Nickel-Aluminum) . . . . . . . . . . .	C-2
	T Type Thermocouple. . . . . . . . . . . . . . . . . . . . . . . . . . . .	C-3

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Table of Contents	iv

(Copper vs. Copper-Nickel <Constantan>) . . . . . . . . . . C-3 E Type Thermocouple. . . . . . . . . . . . . . . . . . . . . . . . . . . . C-4 (Nickel-Chromium vs. Copper-Nickel <Constantan>) . . . C-4 S and R Type Thermocouples . . . . . . . . . . . . . . . . . . . . . . C-5

S (Platinum-10% Rhodium vs. Platinum)

R (Platinum-13% Rhodium vs. Platinum) . . . . . . . . . . . C-5

Appendix D

Thermocouple Types

Appendix E

Configuring the 1746-NT4 Module with RSLogix 500

Glossary

Index

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Preface

Who Should Use this Manual

Purpose of this Manual

Read this preface to familiarize yourself with the rest of the manual. The preface includes:

•Who Should Use this Manual

•Purpose of this Manual

•Common Techniques Used in this Manual

Use this manual if you are responsible for designing, installing, programming, or troubleshooting control systems that use SLC 500 4-Channel Thermocouple/mV Input Module.

You should have a basic understanding of electrical circuitry and familiarity with relay logic. If you do not, obtain the proper training before using this product.

This manual describes the procedures you use to install, wire, and troubleshoot your 4-channel thermocouple/mV module. This manual:

•explains how to install and wire your module

•gives you an overview of the SLC 500 programmable controller system

Refer to your programming software user documentation for more information on programming your SLC 500 programmable controller.

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2 Preface

Related Documentation

The following documents contain additional information concerning

Rockwell Automation products. To obtain a copy, contact your local

Rockwell Automation office or distributor.

		For	Read this Document	Document Number
		In-depth information on the SLC Instruction Set.	SLC 500 Instruction Set Reference Manual	1747-RM001
		A description on how to install and use your Modular SLC 500	SLC 500 Modular Hardware Style User	1747-UM011
		programmable controller.	Manual
		A description on how to install and use your Fixed SLC 500	Installation & Operation Manual for Fixed	1747-6.21
		programmable controller.	Hardware Style Programmable Controllers
		A description on how to install the SLC 500 4-Channel	SLC 500 4-Channel Thermocouple/mV	1746-IN010
		Thermocouple/mV input module	Module Installation Instructions
		Information on reducing electrical noise.	System Design for Control of Electrical	GMC-RM001
			Noise
		In-depth information on grounding and wiring Allen-Bradley®	Allen-Bradley Programmable Controller	1770-4.1
		programmable controllers.	Grounding and Wiring Guidelines
		A description of important differences between solid-state	Application Considerations for Solid-State	SGI-1.1
		programmable controller products and hard-wired electromechanical	Controls
		devices.
		An article on wire sizes and types for grounding electrical	National Electrical Code - Published by the National Fire Protection
		equipment.	Association of Boston, MA.
		A glossary of industrial automation terms and abbreviations.	Allen-Bradley Industrial Automation	AG-7.1
			Glossary

Publication 1746-UM007C-EN-P - July 2004

Preface 3

If you would like a manual, you can:

•download an electronic version from the internet at:

–www.theautomationbookstore.com

–http://www.ab.com/manuals

•order a printed manual by:

–contacting your local distributor or Rockwell Automation representative

–visiting www.theautomationbookstore.com

–calling 1.800.963.9548 (USA/Canada) or 001.330.725.1574 (Outside USA/Canada)

Common Techniques Used in this Manual

Your Questions or Comments on this Manual

If you find a problem with this manual, or you have any suggestions for how this manual could be made more useful to you, please contact us at the address below:

Rockwell Automation

Automation Control and Information Group

Technical Communication, Dept. A602V

P.O. Box 2086

Milwaukee, WI 53201-2086

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.

•Italic type is used for emphasis.

Publication 1746-UM007C-EN-P - July 2004

4 Preface

Publication 1746-UM007C-EN-P - July 2004

Chapter 1

Overview

General Description

This chapter describes the thermocouple/millivolt module and explains how the SLC controller gathers thermocouple or millivolt initiated analog input from the module. This chapter includes:

•General Description

•System Overview

The thermocouple/mV module receives and stores digitally converted thermocouple and/or millivolt (mV) analog data into its image table for retrieval by all fixed and modular SLC 500 processors. The module supports connections from any combination of up to four thermocouple or mV analog sensors.

The following tables define thermocouple types and their associated full scale temperature ranges and also list the millivolt analog input signal ranges that each 1746-NT4 channel will support. To determine the practical temperature range your thermocouple supports, refer to the specifications in Appendix A.

Type	°C Temperature Range		°F Temperature Range
J	-210° to 760°		-346° to 1400°
K	-270° to 1370°		-454° to 2498°
T	-270° to 400°		-454° to 752°
B	300° to 1820°		572° to 3308°
E	-270° to 1000°		-454° to 1832°
R	0° to 1768°		32° to 3214°
S	0° to 1768°		32° to 3214°
N	0° to 1300°		32° to 2372°
CJC Sensor	0° to 85°		32° to 185°
Millivolt Input Type		Range
±50 mV		-50 mV dc to +50 mV dc
±100 mV		-100 mV dc to +100 mV dc

Each input channel is individually configurable for a specific input device and provides open-circuit, over-range, and under-range detection and indication.

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1-2 Overview

Channel Status

LEDs (Green)

Module Status

LED (Green)

Removable

Terminal Block

CJC Sensors

Cable Tie Slots

Hardware Features

The thermocouple module fits into any single-slot, except the processor slot (0), in either an SLC 500 modular system or an SLC 500 fixed system expansion chassis (1746-A2). It is a Class 1 module (uses 8 input words and 8 output words). It interfaces to thermocouple types J, K, T, E, R, S, B, and N, and supports direct ±50 mV and ±100 mV analog input signals.

The module requires the use of Block Transfer in a remote configuration.

The module contains a removable terminal block providing connection for four thermocouple and/or analog input devices. There are also two, cold-junction compensation (CJC) sensors used to compensate for offset voltages introduced into the input signal as a result of the cold-junction, i.e., where the thermocouple wires connect to the module wiring terminal. There are no output channels on the module. Module configuration is done via the user program. There are no DIP switches.

INPUT							Door Label
CHANNEL		0			2
STATUS		1			3

MODULE STATUS

THERMOCOUPLE/mV
CJC A+
Do Not
Remove	CHL0+
CJC A_
Do Not	CHL0 _
Remove
SHIELD
	CHL1+
SHIELD
	CHL1_
SHIELD
	CHL2+
SHIELD
	CHL2_
SHIELD
CJC B_	CHL3+
Do Not	CHL3 _
Remove
CJC B+
Do Not
Remove	ANLG
	COM

Side Label

	x xxx-NT4	SERIAL	1746	CAT	MODULE INPUT THERMOCOUPLE/mV	500 SLC
		.NO	NT4
		FRN	®	SER
		2.DIV D, AND C B, A, GROUPS I, CLASS		U
			SA .EQ CONT. .IND LISTED L A196 .LOC .HAZ FOR
			OPERATING TEMPERATURE ® T3C CODE
	USA IN MADE 1M FAC	_ _
		+100mVDC to 100mVDC	TAGE:VOL +50mVDC to 50mVDC	N B, S, R, E, T, K, J,	TYPES:THERMOCOUPLE	RANGES SIGNAL INPUT

Self-Locking Tabs

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Overview 1-3

System Overview

Hardware	Function
Channel Status LED	Display operating and fault status of
Indicators	channels 0, 1, 2, and 3
Module Status LED	Displays module operating and fault status
Side Label (Nameplate)	Provides module information
Removable Terminal Block	Provides physical connection to input devices.
	It is color coded green.
Door Label	Permits easy terminal identification
Cable Tie Slots	Secure and route wiring from module
Self-Locking Tabs	Secure module in chassis slot

General Diagnostic Features

The thermocouple/mV module contains diagnostic features that can help you identify the source of problems that may occur during power-up or during normal channel operation. These power-up and channel diagnostics are explained in chapter 7, Module Diagnostics and Troubleshooting.

The thermocouple 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 thermocouple modules in your system as the power supply can support.

SLC Processor

Thermocouple Modules

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1-4 Overview

Each individual channel on the thermocouple module can receive input signals from thermocouple sensors or mV analog input devices. You configure each channel to accept either input. When configured for thermocouple input types, the thermocouple module converts the analog input voltages into cold-junction compensated and linearized, digital temperature readings. The 1746-NT4 uses the National Bureau of Standards (NBS) Monograph 125 and 161 based on IPTS-68 for thermocouple linearization.

When configured for millivolt analog inputs, the module converts the analog values directly into digital values. The module assumes that the mV input signal is already linear.

System Operation

At power-up, the thermocouple module performs a check of its internal circuits, memory, and basic functions. During this time the module status LED remains off. If no faults are found during the power-up diagnostics, the module status LED is turned on.

			Channel Data Word
		Thermocouple	ChannelStatus Word
			SLC 500
	Thermocouple or mV	Input
			Processor
	Analog Signals	Module
			Channel Configuration Word

After power-up checks are complete, the thermocouple module waits for valid channel configuration data from your SLC ladder logic program (channel status LEDs off). After configuration data is written to one or more channel configuration words and their channel enable status bits are set, the channel status LEDs go on and the thermocouple module continuously converts the thermocouple or millivolt input to a value within the range you selected for the enabled channels.

Each time a channel is read by the module, that data value is tested by the module for a fault condition, i.e. open 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 blinks.

The SLC processor reads the converted thermocouple or millivolt data from the module at the end of the program scan, or when commanded by the ladder program. The processor and thermocouple module determine that the backplane data transfer was made without error, and the data is used in your ladder program.

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ANALOG COM

Overview 1-5

Module Operation

The thermocouple module input circuitry consists of four differential analog inputs multiplexed into a single analog-to-digital (A/D) convertor. The mux circuitry also continuously samples the CJC A and CJC B sensors and compensates for temperature changes at the cold junction (terminal block). The figure on the following page shows a block diagram for the analog input circuitry.

The A/D convertor reads the selected input signal and converts it to a digital value. The multiplexer sequentially switches each input channel to the module’s A/D convertor. Multiplexing provides an economical means for a single A/D convertor to convert multiple analog signals. However, it does affect the speed at which an input signal can change and still be detected by the convertor.

Thermocouple Compatibility

The thermocouple module is fully compatible with all SLC 500 fixed and modular controllers. It is compatible with all NBS MN-125 standard types J, K, T, E, R, S, and B thermocouple sensors and extension wire; and with NBS MN-161, 14AWG, standard type N thermocouple and extension wire. Refer to Appendix C for more details.

The Series B (or higher) 1746-NT4 differential design allows for a maximum channel-to-channel common-mode voltage difference/separation of 2 volts. This means that if you are using an NT4 with multiple grounded thermocouples with metallic sheaths or exposed thermocouples with measuring junctions that make contact with electrically conductive material, their ground potentials must be within 2 volts. If this is not done, your temperature readings will be inaccurate or the module could be damaged. If your grounded thermocouple protective sheath is made of an electrically non-conductive material such as ceramic, then the voltage separation specification is not as important. Refer to Appendix D for an explanation of grounded, ungrounded, and exposed thermocouples.

Use the analog common (ANALOG COM) terminal for applications that have multiple grounded thermocouples. This analog common terminal must be jumpered to either the (+) or (-) terminal of any active channel which is connected to a grounded thermocouple. See Wiring Considerations on page 3-8 for complete information on the use of the terminal.

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1-6 Overview

Input Circuit Block Diagram

		Input Circuit Block Diagram
	Terminal Block		Module Circuitry
		+
	CJCA Sensor	-
			Open Circuit
			Detection
	Channel 0	+
		-
	ungrounded	Shield
	thermocouple				User-Selected
	Channel 1	+		Filter Frequency
		-
		Shield
within	grounded			Analog to	Digital	Digital
2V*	thermocouple		Multiplexer	Digital
					Filter	Value
	Channel 2	+		Convertor
		-
		Shield
within	grounded
	thermocouple
2V*
	Channel 3	+

- *See Important note below.

Shield

grounded thermocouple

	user supplied	Analog
	jumper
		Common
		+
	CJCB Sensor	-

Chassis Ground (internally connected)

	IMPORTANT	When using multiple grounded and/or exposed
		thermocouples that are touching on electrically
		conductive material with Series B or higher
		1746-NT4, the ground potential between any two
		channels cannot exceed 2 volts.

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Overview 1-7

	ATTENTION			The possibility exists that grounded or exposed
				thermocouples can become shorted to a potential
				greater than that of the thermocouple itself. Due to
				possible shock hazard, care should be taken when
				wiring these types of thermocouples. Refer to
				Appendix D for more details.

Linear Millivolt Device Compatibility

A large number of millivolt devices may be used with the 1746-NT4 module. For this reason we do not specify compatibility with any particular device.

However, millivolt applications often use bridges of strain gages. To allow the NT4 Series B (or higher) to operate correctly, the analog common (ANALOG COM) terminal of the module needs to be biased to a level within 2V of the signal of interest. A resistive voltage divider using 10k Ω resistors is recommended to accomplish this. The circuit diagram below shows how this connection is made.

	Strain
	Gage	Vcc +
	Bridge
NT4	fixed	variable	10k Ω
INPUT	+
(CHL0, CHL1,	-
CHL2, CHL3)			10k Ω
	fixed	fixed
ANALOG COM

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1-8 Overview

Publication 1746-UM007C-EN-P - July 2004

Chapter 2

Required Tools and

Equipment

Quick Start for Experienced Users

This chapter can help you to get started using the NT4 4-channel thermocouple/mV module. The procedures are based on the assumption that you have an understanding of SLC 500 products. You should understand electronic process control and be able to interpret the ladder logic instructions required to generate the electronic signals that control your application.

Because it is a start-up guide for experienced users, 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 information about applying the procedures described in each step. It also references other documentation that may be helpful if you are unfamiliar with programming techniques or system installation requirements.

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 includes:

•Required Tools and Equipment

•Installation Procedures

Have the following tools and equipment ready:

•medium blade screwdriver

•medium cross-head screwdriver

•thermocouple or millivolt sensor

•appropriate thermocouple extension wire (if needed)

•4-channel thermocouple/mV input module (1746-NT4)

•programming equipment

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2-2 Quick Start for Experienced Users

Installation Procedures

1.	Check the contents of shipping box.	Reference

Unpack the shipping box making sure that the contents include:

• thermocouple input module (Catalog Number 1746-NT4)

• removeable terminal block (factory installed on module) with CJC sensors attached.

• installation instructions (publication 1746-IN010)

If the contents are incomplete, call your local Allen-Bradley representative for assistance.

		2.	Ensure your chassis supports placement of the 1746-NT4 module	Reference
			Review the power requirements of your system to see that your chassis supports placement of the	Chapter 3
			thermocouple input module.	(Installion and
			• For modular style systems, calculate the total load on the system power supply using the	Wiring
				Appendix A
			procedure described in the SLC 500 Modular Hardware Style User Manual (Publication
			Number 1747-UM011) or the SLC 500 Modular Chassis and Power Supplies Technical Data	(Specifications)
			(Publication Number 1746-TD003).

•The fixed, 2-slot chassis supports 2 thermocouple input modules. If combining a thermocouple module with a different module, refer to the module compatibility table found in chapter 3.

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Quick Start for Experienced Users	2-3

3.	Insert the 1746-NT4 module into the chassis	Reference
	Make sure system power is off; then insert the thermocouple input module into your 1746	Chapter 3
	chassis. In this example procedure, local slot 1 is selected.	(Installation and
		Wiring)

	ATTENTION			Never install, remove, or wire modules with power
				applied to the chassis or devices wired to the
				module.

Top and Bottom

Module Release(s)

Card

Guide

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2-4 Quick Start for Experienced Users

4.

Connect the thermocouple wires

Reference

Connect thermocouple wires to channel 0 on the module’s terminal block. Make sure both cold

Chapter 3

junction compensation (CJC) assemblies are securely attached.

(Installion and

Wiring

Ground the shield drain wire at one end only. The preferred location is to the same point as the

Appendix D

sensor ground reference. For grounded thermocouples or mV sensors, this is at the sensor. For

(Thermocouple

insulated/ungrounded thermocouples, this is at the NT4 module.

Types

Terminal Block

CJC A

CHL 0+

Assembly

CHL 0

_

SHIELD

CHL 1+

SHIELD

CHL 1

_

Thermocouple

Wire

Refer to the paragraph above

5.	Configure the system.	Reference
	Configure your system I/O configuration for the particular slot the NT4 is in (slot 1 in this	Chapter 4
	example). Select the module from the drop-down list or enter the thermocouple input module ID	(Preliminary
	code (3510).	Operating
		Considerations)

When using RSLogix 500 version 6.10 or higher, you may select Advanced Configuration, then Configure, to use the software’s I/O wizard to configure the NT4 (see appendix E for details). If you use this option, proceed to step 8.

Your programming software online help screens

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Quick Start for Experienced Users	2-5

6.	Determine the operating parameters.	Reference
	Determine the operating parameters for channel 0. This example shows the channel 0	Chapter 4
	configuration word defined with all defaults (0) except for channel enable (bit 11). The	(Preliminary
	addressing reflects the location of the module as slot 1.	Operating
		Considerations)

Chapter 5

(Channel

Configuration, Data, and Status)

Appendix B

(NT4 Configuration Worksheet)

SLC 500 Controller

Data Files

Input Image		Output Image
		(8 words)

Address

O:1.0 Word 0 Channel 0 Configuration Word 0

O:1.1	Word 1	Channel 1 Configuration Word
O:1.2	Word 2	Channel 2 Configuration Word
O:1.3	Word 3	Channel 3 Configuration Word
•	•	Words 4 _7
•	•
•	•	(not defined)
O:1.7	Word 7

Bit 15

Unused					Channel Enable	Filter Frequency			Temperature Units	Open Circuit			Data Format					InputType
0		0		0	0	0		0	0	0		0	0		0	0		0		0		0

Default Setting

•Type J Thermocouple

•Engineering Units x 1

•Data Word = 0 If Open Circuit

•Degrees Celsius

•10 Hz. Filter Frequency

•Channel Disabled

Bit 0

0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0

New Setting

Set this bit (11) to enable channel. Address = O:1.0/11.

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2-6 Quick Start for Experienced Users

7.	Program the configuration.	Reference
	Do the programming necessary to establish the new configuration word setting in the previous	Chapter 6
	step.	(Ladder
		Programming
	1. Create integer file N10. Integer file N10 should contain one element for each channel used.
		Examples)

	(For this example we only need one, N10:0.)	Chapter 8
	2. Enter the configuration parameters from step 6 for channel 0 into integer N10:0.
		(Application
	In this example all the bits of N10:0 will be zero except for the channel enable (N10:0/11).
		Examples)
	3. Program an instruction in your ladder logic to copy the contents of N10:0 to output word O:1.0.

Example of Data Table for Integer File N10:

	address	15			data		0
	N10:0	0000 1000 0000					0000
	First Pass Bit
	S:1				COP
	] [				COPY FILE
	15				Source # N10:0
				Dest # O:1.0
				Length 1

address

15

data

0

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 the channel. .

8.

Write the ladder program.

Reference

Write the remainder of the ladder logic program that specifies how your thermocouple input data

Chapter 5

will be processed for your application. In this procedure the addressing reflects the location of

(Channel

the module as slot 1.

Configuration,

Data, and

Status)

SLC 500 Controller

Chapter 6

Data Files

(Ladder

Input Image

Output Image

Programming

Examples)

(8 words)

Address

Chapter 8

Address

I:1.0

(Application

I:1.0

Word 0

Channel 0 DataWord

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Examples)

I:1.1

Word 1

Channel 1 Data Word

Bit 15

(Variable Thermocouple Input Data) Bit 0

Your

I:1.2

Word 2

Channel 2 Data Word

I:1.3

Word 3

Channel 3 Data Word

programming

device user

•

•

Channel 0 Status Word

manual.

•

•

Channel 1 Status Word

•

•

Channel 2 Status Word

I:1.7

Word 7

Channel 3 Status Word

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Quick Start for Experienced Users	2-7

9.	Go through the system start-up proceedure.	Reference
	Apply power. Download your program to the SLC and put the controller into Run mode. In this	Chapter 7
	example during a normal start up, the module status LED and channel status 0 LED turn on.	(Module
		Diagnostics and
		Troubleshooting)

INPUT

CHANNEL

0

2

Channel LEDs

STATUS

1

3

Module Status LED

MODULE STATUS

THERMOCOUPLE/mV

10.

Check module operation.

Reference

(Optional) Monitor the status of input channel 0 to determine its configuration setting and

Chapter 5

operational status. This is useful for troubleshooting when the blinking channel LED indicates

(Channel

that an error has occurred. If the Module Status LED is off, or if the Channel 0 LED is off or

Configuration,

	blinking, refer to chapter 7.	Data, and
		Status)
		Chapter 6
		(Ladder
		Programming
		Examples)
		Chapter 8
		(Application
		Examples)

SLC 500 Controller

Data Files

	Input Image		Output Image
	(8 words)

Word 0	Channel 0 Data Word
Word 1	Channel 1 Data Word
Word 2	Channel 2 Data Word
Word 3	Channel 3 Data Word

Channel 0 Status Word

•Channel 1 Status Word

•Channel 2 Status Word Word 7 Channel 3 Status Word

		Configuration Error	Over Range Error	Under Range Error	Open Circuit Error	Channel Status	Filter Frequency			Temperature Units	Open CircuitType			Data Format				Input Type
		0	0	0	0	1	0		0	0	0		0	0		0	0	0		0	0
Bit 15									Address												Bit 0

I:1.4

For this example, during normal operation only bit 11 is set.

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2-8 Quick Start for Experienced Users

Publication 1746-UM007C-EN-P - July 2004

Chapter 3

Installation and Wiring

Compliance to European Union Directives

This chapter provides:

•Compliance to European Union Directives

•Electrostatic Discharge

•NT4 Power Requirements

•Module Location in Chassis

•Module Installation and Removal

•Terminal Wiring

•Thermocouple Calibration

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

The Series B (or higher) 1746-NT4 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.

Publication 1746-UM007C-EN-P - July 2004

3-2 Installation and Wiring

Electrostatic Discharge

Electrostatic discharge can damage semiconductor devices inside this module if you touch backplane connector pins. 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.

•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.

NT4 Power Requirements	The thermocouple module receives its power through the SLC500
	chassis backplane from the fixed or modular +5 VDC/+24 VDC chassis
	power supply. The maximum current drawn by the module is shown
	in the table below.

5V dc Amps	24V dc Amps
0.06	0.04

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 2-slot expansion chassis on page 3-3.

Publication 1746-UM007C-EN-P - July 2004