Allen-Bradley SLC 500 1746-NR4 User Manual
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Allen-Bradley SLC 500 1746-NR4 User Manual

Rtd/resistance input module
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Allen-Bradley
SLC 500t
RTD/Resistance
Input Module
(Cat. No. 1746-NR4)
AB Spares
User
Manual

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Summary of Contents for Allen-Bradley SLC 500 1746-NR4

  • Page 1 Allen-Bradley User SLC 500t RTD/Resistance Manual Input Module (Cat. No. 1746-NR4) AB Spares...
  • Page 2 Reproduction of the contents of this copyrighted publication, in whole or in part, without written permission of Allen-Bradley Company, Inc., is prohibited. Throughout this manual we use notes to make you aware of safety...
  • Page 3 Summary of Changes Summary of Changes The information below summarizes the changes to this manual since the last printing as 1746-6.7–January 1997. To help you find new information and updated information in this release of the manual, we have included change bars as shown to the right of this paragraph.

  • Page 4: Table Of Contents

    Table of Contents RTD/Resistance Input Module User Manual Preface Who Should Use this Manual ........P–1 Purpose of this Manual .
  • Page 5 Table of Contents RTD/Resistance Input Module User Manual Wiring Resistance Devices (Potentiometers) to the NR4 Module ..3–9 Wiring Input Devices to the NR4 Module ......3–12 Calibration .
  • Page 6 Table of Contents RTD/Resistance Input Module User Manual User–set Scaling – ........5–15 Configuration Words For User–set Scaling (Words 4 to 7) .
  • Page 7 Table of Contents RTD/Resistance Input Module User Manual Channel Configuration ........8–1 Program Listing .

  • Page 8: Preface

    Preface Preface Read this preface to familiarize yourself with the rest of the manual. This preface covers the following topics: who should use this manual the purpose of this manual terms and abbreviations conventions used in this manual Allen–Bradley support Who Should Use this Use this manual if you are responsible for designing, installing, Manual...

  • Page 9: Contents Of This Manual

    Preface Contents of this Manual Chapter Title Contents Describes the purpose, background, and scope of this manual. Also specifies the audience for whom Preface this manual is intended and defines key terms and abbreviations used throughout this book. Provides a hardware and system overview. Overview Explains and illustrates the theory behind the RTD input module.

  • Page 10: Related Documentation

    9399-APSQS programming in the shortest time possible A procedural and reference manual for technical personnel who use an Allen-Bradley Hand-Held Terminal User’s Manual 1747–NP002 HHT to develop control applications An introduction to HHT for first–time users, containing basic concepts but...

  • Page 11: Terms And Abbreviations

    Preface Terms and Abbreviations The following terms and abbreviations are specific to this product. For a complete listing of Allen–Bradley terminology, refer to the Allen–Bradley Industrial Automation Glossary, Publication Number AG–7.1. A/D – Refers to the analog–to–digital converter inherent to the RTD/Resistance input module.
  • Page 12 Preface Preface effective resolution – The amount of jitter (data variation) that typically occurs in the data word due to the influence of the internal electrical noise in the module. filter frequency – The user–selectable first–notch frequency for the A/D converter’s digital filter.

  • Page 13: Common Techniques Used In This Manual

    Preface resistance of metals increases with temperature. When a small current is applied to the RTD, it creates a voltage that varies with temperature. This voltage is processed and converted by the RTD module into a temperature value. sampling time – The time required by the A/D converter to sample an input channel.

  • Page 14: Your Questions Or Comments On This Manual

    Preface Preface Your Questions or Comments on this Manual If you find a problem with this manual, please notify us of it on the enclosed Publication Problem Report. If you have any suggestions for how this manual could be made more useful to you, please contact us at the address below: Allen–Bradley Company, Inc.
  • Page 15 Preface Notes: AB Spares P–8...

  • Page 16: Overview

    Chapter Overview This chapter describes the 4–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: 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 will be referred to as simply the RTD module.
  • Page 17 Chapter 1 Overview Figure 1.1 Simplified RTD Module Circuit Constant Current Source C= 0.5 or 2 mA RTD Module Sense Return Sense µP Circuit Digital Data Digital Data Conversion Return Sense Return Sense Return AB Spares 1–2...

  • Page 18: Rtd Compatibility

    Chapter 1 Overview RTD Compatibility Table 1.A lists the RTD types you can use with the RTD module and gives each type’s associated temperature range, resolution, and repeatability specifications. Table 1.B shows the accuracy and temperature drift specifications for the RTDs. Table 1.A RTD Temperature Ranges, Resolution, and Repeatability Temp.
  • Page 19 Chapter 1 Overview Table 1.B RTD Accuracy and Temperature Drift Specifications Accuracy Accuracy Temperature Drift Temperature Drift RTD Type (0.5 mA Excitation) (2.0 mA Excitation) (0.5 mA Excitation) (2.0 mA Excitation)  1.0 C  0.5 C  0.034 C/ C  0.014 C/ C 100W ( 2.0 F)

  • Page 20: Resistance Device Compatibility

    Chapter 1 Overview Resistance Device Compatibility Table 1.C lists the resistance input types you can use with the RTD module and gives each type’s associated specifications. Table 1.C Resistance Input Specifications Resistance Range Resistance Range Input Type Accuracy Temperature Drift Resolution Repeatability (0.5 mA Excitation)

  • Page 21: General Diagnostic Features

    Chapter 1 Overview Figure 1.2 RTD Module Hardware INPUT CHANNEL STATUS MODULE STATUS RTD/resistance SHIELD SHIELD CHL 0 CHL 1 CHL 0 SENSE CHL 1 SENSE CHL 0 RETRN CHL 1 RETRN SHIELD SHIELD CHL 2 CHL 3 CHL 2 SENSE CHL 3 SENSE...

  • Page 22: System Overview

    Chapter 1 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.

  • Page 23: System Operation

    Chapter 1 Overview System Operation The RTD module has 3 operational states: power–up module operation error (module error and channel error) Power–up At power–up, the RTD module checks its internal circuits, memory, and basic functions via hardware and software diagnostics. During this time the module status LED remains off.

  • Page 24: Led Status

    Chapter 1 Overview LED Status Figure 1.4 shows the RTD module LED panel consisting of 5 LEDs. The state of the LEDs (for example, off, on, or blinking) depends on the operational state of the module (see Table 1.E). Figure 1.4 LED Indicators INPUT CHANNEL...

  • Page 25: Module To Processor Communication

    Chapter 1 Overview Module to Processor Communication As shown in Figure 1.5, the RTD module communicates with the SLC processor through the backplane of the chassis. The RTD module transfers data to / receives data from the processor by means of an image table. The image table (Table 1.F) consists of 8 input words and 8 output words.

  • Page 26: Quick Start Guide

    Chapter 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 it is a start–up guide, this chapter does not contain detailed explanations about the procedures listed.

  • Page 27: Procedures

    Chapter 2 Quick Start Procedures Procedure: Unpacking Module Reference Unpack the module making sure that the contents include: RTD module (Catalog Number 1746–NR4) – Installation instructions (Publication Number 1746–5.17) If the contents are incomplete, call your local Allen–Bradley representative for assistance. Procedure: Determining Power Requirements Reference Chapter 3...
  • Page 28 Chapter 2 Quick Start Procedure: Wiring Module Reference Chapter 3 Connect RTD (Figure 2.2) or potentiometer (Figure 2.3 or Figure 2.4) wire leads to channel 0 of the (Installation and RTD module. Wiring) Figure 2.2 RTD Connections To Terminal Block For details on wiring an RTD to the module, see chapter 3.
  • Page 29 Chapter 2 Quick Start Figure 2.3 2–Wire Potentiometer Connections To Terminal Block For details on wiring a potentiometer to the module, see chapter 3. Cable Shield Add Jumper Potentiometer Shield Chl 0 RTD Chl 0 Sense Return Chl 0 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.
  • Page 30 Chapter 2 Quick Start Figure 2.4 3–Wire Potentiometer Connections To Terminal Block For details on wiring a potentiometer to the module, see chapter 3. Cable Shield Run RTD and sense wires from module to potentiometer terminal and tie them to one point. Shield Potentiometer Chl 0 RTD...
  • Page 31 Chapter 2 Quick Start Procedure: Configuring Your I/O Reference Chapter 4 Configure your system I/O configuration for the particular slot where the RTD module resides (slot 1 in (Preliminary this example). Using APS software, select the 1746–NR4 from the list of modules, or if it is not listed Operating in your software version, select Other and enter the RTD module ID code (3513) at the prompt on Considerations)
  • Page 32 Chapter 2 Quick Start Procedure: Configuring the Module Reference Chapter 4 Determine the operating parameters for channel 0. In this example, Figure 2.5 shows the channel 0 (Preliminary configuration word defined with all defaults (0) except for channel enable (bit 11). The addressing Operating reflects the location of the module as slot 1.
  • Page 33 Chapter 2 Quick Start Procedure: Programming the Configuration Reference Do the programming necessary to establish the new configuration word setting in the previous step. Chapter 6 (Ladder 1. Using the memory map function, create integer file N10. Integer file N10 should contain one element for each channel used.
  • Page 34 Chapter 2 Quick Start Procedure: Write Remaining Ladder Logic Reference Chapter 5 (Channel As shown in Figure 2.7, the Channel Data Word contains the information that represents the Configuration, temperature value or resistance value of the input channel. Write the remainder of the ladder logic Data, and Status) program that specifies how your RTD/resistance input data will be processed for your application.
  • Page 35 Chapter 2 Quick Start Procedure: Test Your RTD Program Reference Chapter 7 Apply power. Download your program to the SLC and put the controller into Run mode. In this exam- (Module ple during a normal start up, the module status LED (Figure 2.8) and channel 0 status LED turn on. Diagnostics and Troubleshooting) Figure 2.8...
  • Page 36 Chapter 2 Quick Start Procedure: Program Functional Check (Optional) Reference (Optional) Monitor the status of input channel 0 to determine its configuration setting and operational Chapter 5 status (Figure 2.9). This is useful for troubleshooting when the blinking channel LED indicates that an (Channel error has occurred.
  • Page 37 Chapter 2 Quick Start Notes: AB Spares 2–12...

  • Page 38: Installation And Wiring

    Chapter Installation and Wiring 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 Compliance to European If this product has the CE mark it is approved for installation within the Union Directives...

  • Page 39: Electrostatic Damage

    Chapter 3 Installation and Wiring Electrostatic Damage 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.

  • Page 40: Module Location In Chassis

    Chapter 3 Installation and Wiring Module Location in Chassis Modular Chassis Considerations Fixed Controller Compatibility Table Place your RTD module in any slot of an SLC 500 modular chassis (except 5V dc 24V dc slot 0) or a modular expansion chassis. Slot 0 is reserved for the modular (Amps) (Amps) processor or adapter modules.

  • Page 41: Module Installation And Removal

    Chapter 3 Installation and Wiring Module Installation and When installing the module in a chassis, it is not necessary to remove the Removal 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, as shown below, to identify the module location and type.

  • Page 42: Installing The Module

    Chapter 3 Installation and Wiring Installing the Module 1. Align the circuit board of the RTD module with the card guides located at the top and bottom of the chassis as shown in the following figure. Figure 3.2 Module Insertion Into the Chassis Top and Bottom Module Release(s) Card...

  • Page 43: Terminal Wiring

    Chapter 3 Installation and Wiring Terminal Wiring The RTD module contains an 18–position, removable terminal block. The terminal pin–out is shown in Figure 3.3. 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.
  • Page 44 Chapter 3 Installation and Wiring As shown in Figure 3.4, three configurations of RTDs can be connected to the RTD module, namely: 2–wire RTD, which is composed of 2 RTD lead wires (RTD and Return) 3–wire RTD, which is composed of a Sense and 2 RTD lead wires (RTD and Return) 4–wire RTD, which is composed of 2 Sense and 2 RTD lead wires (RTD and Return).
  • Page 45 Chapter 3 Installation and Wiring Figure 3.4 RTD Connections To Terminal Block Cable Shield 2–Wire RTD Interconnection Shield Add Jumper Chl 0 RTD Chl 0 Sense Terminal Pin–outs Return Return Chl 0 Return Shield Belden #9501 Shielded Cable Shield Chl 0 Chl 1 3–Wire RTD Interconnection Chl 0...

  • Page 46: Wiring Resistance Devices (Potentiometers) To The Nr4 Module

    Chapter 3 Installation and Wiring When using a 3–wire configuration, the module compensates for resistance error due to lead wire length . For example, in a 3–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.
  • Page 47 Chapter 3 Installation and Wiring Figure 3.5 2–Wire Potentiometer Connections To Terminal Block 2–Wire Potentiometer Interconnection Cable Shield Add Jumper Potentiometer Shield Chl 0 RTD Chl 0 Sense Return Chl 0 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.
  • Page 48 Chapter 3 Installation and Wiring Figure 3.6 3–Wire Potentiometer Connections To Terminal Block Cable Shield Run RTD and sense wires from module to potentiometer terminal and tie them to one point. Shield Potentiometer Chl 0 RTD Sense Chl 0 Sense Return Chl 0 Return Belden #83503 or Belden #9533 Shielded Cable...

  • Page 49: Wiring Input Devices To The Nr4 Module

    Chapter 3 Installation and Wiring To wire your NR4 module, follow these steps as shown in Figure 3.7: 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–inch) lengths. Strip about 4.76 mm (3/16 inch) of insulation away to expose the end of the wire.

  • Page 50: Calibration

    Chapter 3 Installation and Wiring Calibration The accuracy of a system that uses the RTD module is determined by the following: 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.

  • Page 51: Single–Point Calibration

    Chapter 3 Installation and Wiring To maintain system accuracy we recommend that you periodically perform an autocalibration cycle, for example: 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 autocalibration programming example is provided in chapter 6.

  • Page 52: Module Id Code

    Chapter 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...

  • Page 53: Module Addressing

    Chapter 4 Preliminary Operating Considerations Module Addressing The memory map shown in Figure 4.1 displays how the output and input image tables are defined for the RTD module. Figure 4.1 Memory Map Bit 15 Bit 0 Address O:e.0 Channel 0 Configuration Word Word 0 Channel 1 Configuration Word Word 1...

  • Page 54: Input Image - Data Words And Status Words

    Chapter 4 Preliminary Operating Considerations 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.

  • Page 55: Channel Step Response

    Chapter 4 Preliminary Operating Considerations 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.

  • Page 56: Effective Resolution

    Chapter 4 Preliminary Operating Considerations Effective Resolution The effective resolution for an input channel depends upon the filter frequency selected for that channel. The following table displays the effective resolution for the various input types and filter frequencies: Table 4.B Effective Resolution for RTD and Resistance Inputs Filter Frequency Input...

  • Page 57: Channel Cut-Off Frequency

    Chapter 4 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.
  • Page 58 Chapter 4 Preliminary Operating Considerations Figure 4.2 10 Hz Filter Notch Frequency –3 dB –20 –40 –60 –80 –100 Amplitude (in dB) –120 –140 –160 –180 –200 Frequency 2.62 Hz Frequency Response Figure 4.3 50 Hz Filter Notch Frequency –3 dB –20 –40 –60...
  • Page 59 Chapter 4 Preliminary Operating Considerations Figure 4.4 60 Hz Filter Notch Frequency –3 dB –20 –40 –60 –80 Amplitude (in dB) –100 –120 –140 –160 –180 –200 Frequency 15.72 Hz Frequency Response Figure 4.5 250 Hz Filter Notch Frequency –3 dB –20 –40 –60...

  • Page 60: Scanning Process And Channel Timing

    Chapter 4 Preliminary Operating Considerations Scanning Process and This section shows how to determine the channel update time and channel Channel Timing 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.
  • Page 61 Chapter 4 Preliminary Operating Considerations The fastest module update time occurs when only one channel with a 250 Hz filter frequency is enabled. Module Update Time = 17 ms NOTE: 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.

  • Page 62: Channel Turn-On, Turn-Off, And Reconfiguration Times

    Chapter 4 Preliminary Operating Considerations Channel Turn–On, Turn–Off, The table below gives you the turn–on, turn–off, and reconfiguration times and Reconfiguration Times for enabling or disabling a channel. Description Duration Requires up to one module update time plus one of the The time it takes to make converted data available in the data following: word and to set the status bit (transition from 0 to 1) in the...
  • Page 63 Chapter 4 Preliminary Operating Considerations Notes: AB Spares 4–12...

  • Page 64: Channel Configuration

    Chapter Channel Configuration, Data, and Status This chapter 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. It gives you information about how to: configure a channel examine channel input data check a channel’s status...

  • Page 65: Channel Configuration Procedure

    Chapter 5 Channel Configuration, Data, and Status Channel Configuration The channel configuration word consists of bit fields, the settings of which Procedure determine how the channel operates. This procedure looks at each bit field separately and helps you configure a channel for operation. Refer to Table 5.A and the bit field descriptions that follow for complete configuration information.

  • Page 66: Enter The Configuration Data

    Chapter 5 Channel Configuration, Data, and Status and upper limits in words 4 and 5 (defines range 0) or 6 and 7 (defines range 1). 9. Make sure a zero is in bit 15. This bit is not used. 10. Build the channel configuration word using the configuration worksheet on page iv for every channel on each RTD module repeating the procedures given in steps 1–9.
  • Page 67 Chapter 5 Channel Configuration, Data, and Status Table 5.A Channel Configuration Word (O:e.0 through O:e.3) – Bit Definitions Make these bit settings in the Channel Configuration Word Bit(s) it s Define efine To Select o elect É É É 100W Pt RTD (385) É...

  • Page 68: Input Type Selection (Bits 0-3)

    Chapter 5 Channel Configuration, Data, and Status 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 Table 5.A.
  • Page 69 Chapter 5 Channel Configuration, Data, and Status 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 and 16383. Zero (0) corresponds to the lowest temperature value of the RTD type or the lowest resistance value (ohms).
  • Page 70 Chapter 5 Channel Configuration, Data, and Status 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).

  • Page 71: Scaling Examples

    Chapter 5 Channel Configuration, Data, and Status Scaling Examples The following examples are using the default scaling ranges: Scaled–for–PID to Engineering Units Equation: Engr Units Equivalent = S + [ (S – S ) x (Scaled–for–PID value displayed / 16383) ] HIGH Assume that the input type is an RTD, Platinum ( 0.00385 C...
  • Page 72 Chapter 5 Channel Configuration, Data, and Status Table 5.C 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 RTDs vary with excitation current, for example, 1000Ω...
  • Page 73 Chapter 5 Channel Configuration, Data, and Status Table 5.F Data Format for 10Ω Copper 426 RTD Data Format Engineering Units x 1 Engineering Units x 10 Excitation Current Excitation Current Proportional Counts Proportional Counts Scaled–for–PID cale –for–PI (Default) 0.1 C 0.1 F 1.0 C 1.0 F...
  • Page 74 Chapter 5 Channel Configuration, Data, and Status Table 5.J shows the data resolution provided by the 1746–NR4 for RTD input types using the various data formats. Table 5.J Channel Data Word Resolution for RTDs Data Format (Bits 4 and 5) Proportional Counts Engineering Units x 1 Engineering Units x 10...

  • Page 75: Broken Input Selection (Bits 6 And 7)

    Chapter 5 Channel Configuration, Data, and Status Table 5.L Channel Data Word Resolution for 500W, 1000W, and 3000W Resistance Inputs Data Format (Bits 4 and 5) Proportional Counts Engineering Units x 1 Engineering Units x 10 Scaled–for–PID Resistance Input Type (Default) Ohms Ohms...

  • Page 76: Filter Frequency Selection (Bits 9 And 10)

    Chapter 5 Channel Configuration, Data, and Status Table 5.N Bit Descriptions for Temperature Units Selection Binary Select If you want to Value degrees Celsius display the channel data word in degrees Celsius. degrees Fahrenheit display the channel data word in degrees Fahrenheit. Filter Frequency Selection (Bits 9 and 10) Table 5.O shows the descriptions for bits 9 and 10.

  • Page 77: Excitation Current Selection (Bit 12)

    Chapter 5 Channel Configuration, Data, and Status Table 5.P Bit Descriptions for Channel Enable Selection Binary Select If you want to Value disable a channel. Disabling a channel causes the channel data channel disable word and the channel status word to be cleared. channel enable enable a channel.

  • Page 78: Default Scaling

    Chapter 5 Channel Configuration, Data, and Status Table 5.R Bit Descriptions for Scaling Selection Binary Select If you want to Value configure the module to scale the data word using the default scale range (–32768 to 32767) for Use module defined scaling scaled–for–PID and proportional counts.

  • Page 79: Configuration Words For User-Set Scaling (Words 4 To 7)

    Chapter 5 Channel Configuration, Data, and Status 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 (see Figure 5.4). In this situation, the RTD module returns a number between 3 and 50 in its data word.

  • Page 80: Unused (Bit 15)

    Chapter 5 Channel Configuration, Data, and Status Figure 5.5 Limit Scale Words O:e.4 Defines lower scale limit for range 0 Range 0 O:e.5 Defines upper scale limit for range 0 O:e.6 Defines lower scale limit for range 1 Range 1 O:e.7 Defines upper scale limit for range 1 Unused (Bit 15)

  • Page 81: Channel Data Word

    Chapter 5 Channel Configuration, Data, and Status Channel Data Word 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.

  • Page 82: Channel Status Checking

    Chapter 5 Channel Configuration, Data, and Status Channel Status Checking The channel status word (Figure 5.7) 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.
  • Page 83 Chapter 5 Channel Configuration, Data, and Status Table 5.S Channel 0–3 Status Word (I:e.4 through I:e.7) – Bit Definitions These bit settings Bit(s) it s Define efine In icate t is Indicate this 100W Pt RTD (385) 200W Pt RTD (385) 500W Pt RTD (385) 1000W Pt RTD (385) 100W Pt RTD (3916)

  • Page 84: Input Type Status (Bits 0-3)

    Chapter 5 Channel Configuration, Data, and Status Explanations of the status conditions follow. 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.

  • Page 85: Channel Enable Status (Bit 11)

    Chapter 5 Channel Configuration, Data, and Status 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.

  • Page 86: Out-Of-Range Error (Bit 14)

    Chapter 5 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.
  • Page 87 Chapter 5 Channel Configuration, Data, and Status Notes: AB Spares 5–24...

  • Page 88: Ladder Programming Examples

    Chapter 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.

  • Page 89: Initial Programming

    Chapter 6 Ladder Programming Examples Initial Programming To enter data into the channel configuration word (O:e.0 through O:e.3) when the channel is disabled (bit 11 = 0), follow the example below. Refer to Table 5.A for specific configuration details. Example – As shown in Figure 6.2, configure four channels of a RTD module residing in slot 3 of a 1746 chassis.

  • Page 90: Procedure

    Chapter 6 Ladder Programming Examples Procedure 1. Using the memory map function to create a data file, create integer file N10. Integer file N10 should contain four elements (N10:0 through N10:3). 2. Using the APS data monitor function, enter the configuration parameters for all four RTD channels into a source integer data file N10.

  • Page 91: Dynamic Programming

    Chapter 6 Ladder Programming Examples Dynamic Programming Figure 6.5 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.

  • Page 92: Verifying Channel Configuration Changes

    Chapter 6 Ladder Programming Examples Verifying Channel When executing a dynamic channel configuration change, there will always Configuration Changes be 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.
  • Page 93 Chapter 6 Ladder Programming Examples Check that the configuration written to channel 2 is Rung 2:4 being echoed back in channel 2’s status word. Data valid EQUAL Source A N7:1 Source B Rung 2:5 Data Table address data address data N10:0 0000 1001 0001 0001 N10:3...

  • Page 94: Interfacing To The Pid Instruction

    Chapter 6 Ladder Programming Examples Interfacing to the PID The RTD module was designed to interface directly to the SLC 5/02, SLC Instruction 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.
  • Page 95 Chapter 6 Ladder Programming Examples The Rate and Offset parameters should be set per your application. The Dest is typically an analog output channel. Refer to the APS User Manual or Analog I/O Modules User Manual for specific examples of the SCL Rung 2:2 instruction.

  • Page 96: Using The Proportional Counts Data Format With The User-Set Scaling

    Chapter 6 Ladder Programming Examples Using the Proportional The RTD module can be set up to return data to the user program that is Counts Data Format with the specific to the application. Assume that the user controls the line speed of a conveyor using a 1000Ω...

  • Page 97: Monitoring Channel Status Bits

    Chapter 6 Ladder Programming Examples Monitoring Channel Status Figure 6.9 shows how you could monitor the open– and short–circuit error Bits 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.

  • Page 98: Invoking Autocalibration

    Chapter 6 Ladder Programming Examples Invoking 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 Referring to Figure 6.10, you can command your module to perform an autocalibration cycle by disabling a channel, waiting for the status bit to change state (1 to 0), and then re–enabling that channel.
  • Page 99 Chapter 6 Ladder Programming Examples Important: The RTD module responds to processor commands much more frequently than it updates its own LEDs. 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 ever changing state.

  • Page 100: Module Diagnostics And Troubleshooting

    Chapter Module Diagnostics and Troubleshooting This chapter describes troubleshooting using the channel status LEDs as well as the module status LED. A troubleshooting flowchart is shown in Figure 7.3. It explains the types of conditions that might cause an error to be reported and gives suggestions on how to resolve the problem.

  • Page 101: Led Indicators

    Chapter 7 Module Diagnostics and Troubleshooting A failure of any channel diagnostic test causes the faulted channel status LED 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 user makes the correct change to the channel configuration.

  • Page 102: Error Codes

    Chapter 7 Module Diagnostics and Troubleshooting Table 7.B explains the function of the module status LED. Table 7.B Module Status LED State Table If Module Status Indicated Condition: Corrective Action: LED is: Proper Operation No action required. Cycle power. If condition persists, replace the module or call Module Fault your local distributor or Allen–Bradley for assistance.

  • Page 103: Channel Status Leds (Green)

    Chapter 7 Module Diagnostics and Troubleshooting Channel Status LEDs (Green) The channel LED is used to indicate channel status and related error information contained in the channel status word. This includes conditions such as: normal operation channel–related configuration errors broken input circuit errors such as open– or short–circuit (RTDs only) out–of–range errors All channel errors are recoverable errors and after corrective action, normal operation resumes.

  • Page 104: Out-Of-Range Detection

    Chapter 7 Module Diagnostics and Troubleshooting Out–Of–Range Detection Whenever the data received at the channel data word is out of the defined operating range, an over range or under range error is indicated and bit 14 of the channel status word is set. Important: There is no under range error for a direct resistance input (default scaling).
  • Page 105 Chapter 7 Module Diagnostics and Troubleshooting Figure 7.3 Troubleshooting Flowchart Check LEDs on module. Channel Channel Channel Module Module Status LED is Status LED is Status LED(s) Status LED is off. Status LED is on. blinking off. Channel is Channel is enabled Module fault Normal module not enabled.

  • Page 106: Replacement Parts

    Chapter 7 Module Diagnostics and Troubleshooting Replacement Parts The RTD module has the following replaceable parts: Table 7.C Parts List Part Part Number Replacement Terminal Block 1746–RT25G Replacement Terminal Cover 1746–R13 Series C 1746–NR4 User Manual 1746–6.7 Contacting Allen–Bradley If you need to contact Allen–Bradley for assistance, please have the following information available when you call: a clear statement of the problem including a description of what the system is actually doing.
  • Page 107 Chapter 7 Module Diagnostics and Troubleshooting Notes: AB Spares 7–8...

  • Page 108: Application Examples

    Chapter Application Examples This chapter provides two application examples to help you use the RTD input module. They are defined as a: basic example supplementary example The basic example builds on the configuration word programming provided in chapter 6 to set up one channel for operation. This setup is then used in a typical application to display temperature.
  • Page 109 Chapter 8 Application Examples Figure 8.2 Channel Configuration Worksheet (With Settings Established for Channel 0) É É É É Bit Number É É Channel 0 Channel 1 Channel 2 Channel 3 Input Type Select Data Format select Broken Input Select Temperature Units Select Filter Frequency Select Channel Enable...

  • Page 110: Program Listing

    Chapter 8 Application Examples Program Listing Since a 7–segment LED display is used to display temperature (Figure 8.1), the temperature data must be converted to BCD. The 16–bit data word representing the temperature value is converted into BCD values by the program shown in Figure 8.3.

  • Page 111: Supplementary Example

    Chapter 8 Application Examples Supplementary Example Application Setup (Four Channels C Figure 8.4 shows how to display the temperature of several different RTDs at one annunciator panel. A selector switch (I:2/0) allows the operator to choose between displaying data in C and F. Each of the displays is a 4–digit, 7–segment LED display with the last digit representing tenths of a degree.

  • Page 112: Channel Configuration

    Chapter 8 Application Examples Channel Configuration (see completed worksheet in Figure 8.5) Configuration setup for ambient RTD: channel 0 604 Ω Nickel/Iron (518) display temperature to tenths of a degree Celsius zero data word in the event of an open or short circuit 60 Hz input filter to provide 60 Hz line noise rejection use 2.0 mA excitation current for RTD select module defined scaling...
  • Page 113 Chapter 8 Application Examples Figure 8.5 Channel Configuration Worksheet (With Settings Established) É É É É É É Bit Number É É É Channel 0 (Ambient) Channel 1 (Bath) Channel 2 (Steam) Channel 3 (Chilled H Input Type Select Data Format Select Broken Input Select Temperature Units Select Filter Frequency Select...

  • Page 114: Program Setup And Operation Summary

    Chapter 8 Application Examples Program Setup and Operation Summary 1. Set up two configuration words in memory for each channel, one for C and the other for F. Table 8.A shows the configuration word allocation summary. Table 8.A Configuration Word Allocation Configuration Word Allocation Channel annel...

  • Page 115: Program Listing

    Chapter 8 Application Examples Program Listing The first two rungs of this program (Figure 8.6) send the correct channel setup information to the RTD module based on the position of the degrees selector switch. Figure 8.6 Program to Display Data On LEDs Rung 2.0 If the degrees selector switch is turned to the Fahrenheit position, set up all four channels to read in degrees Fahrenheit.

  • Page 116: Data Table

    Chapter 8 Application Examples Rung 2.4 Write RTD Module Steam Temperature to Display TO BCD Source I:1.2 Dest O:5.0 Rung 2.5 Write RTD Module Chilled Temperature to Display TO BCD Source I:1.3 Dest O:6.0 Rung 2.6 Data Table address data address data N10:0...
  • Page 117 Chapter 8 Application Examples Notes: AB Spares 8–10...

  • Page 118: Electrical Specifications

    Appendix Specifications This appendix lists the specifications for the 1746–NR4 RTD Input Module. Electrical Specifications 50 mA at 5V dc Backplane Current Consumption 50 mA at 24V dc Backplane Power Consumption 1.5W maximum (0.3 W at 5V dc, 1.2 W at 24V dc) External Power Supply Requirements None Number of Channels...

  • Page 119: Module Environmental Specifications

    Appendix A Specifications Module Environmental Specifications Operating Temperature 0 C to +60 C (+32 F to +140 F) −40 C to Storage Temperature 85 C (−40 F to 185 F) Relative Humidity 5% to 95% (without condensation) Hazardous Environment Classification Class I, Division 2 Hazardous Environment Agency Certification UL and CSA Class I, Division 2 Groups A, B, C, D certified...

  • Page 120: Module Accuracy

    Appendix A Specifications Module Accuracy RTD Temperature Ranges, Resolution, and Repeatability Temp. Range Temp. Range RTD Type Resolution Repeatability (0.5 mA Excitation) (2.0 mA Excitation)  0.2 C –200 C to +850 C –200 C to +850 C 0.1 C 100W (–328 F to +1562 F) (–328 F to +1562 F)
  • Page 121 Appendix A Specifications RTD Accuracy and Temperature Drift Specifications Accuracy Accuracy Temperature Drift Temperature Drift RTD Type (0.5 mA Excitation) (2.0 mA Excitation) (0.5 mA Excitation) (2.0 mA Excitation)  1.0 C  0.5 C  0.034 C/ C  0.014 C/ C 100W ( 2.0 F) ( 0.9 F)

  • Page 122: Resistance Device Compatibility

    Appendix A Specifications Resistance Device Compatibility Resistance Input Specifications Resistance Range Resistance Range Input Type Accuracy Temperature Drift Resolution Repeatability (0.5 mA Excitation) (2.0 mA Excitation) 0 W to 150 W 0 W to 150 W  0.04W 150W 0.01W  0.014 W/ C 0 W to 500 W 0 W to 500 W...
  • Page 123 Appendix A Specifications Notes: AB Spares A–6...
  • Page 124 Appendix RTD Standards The following table shows various international and local RTD standards that apply to the 1746–NR4: α RTD Type D100 SAMA JIS (old) JIS (new) Minco 100 W Platinum 0.00385 200 W Platinum 0.00385 500 W Platinum 0.00385 1000 W Platinum 0.00385 100 W Platinum...
  • Page 125 Appendix B RTD Standards Notes: AB Spares B–2...
  • Page 126 Appendix Configuration Worksheet for RTD/Resistance Module The following configuration procedure and worksheet are provided to help you configure each of the channels on your RTD module. The channel configuration word consists of bit fields, the settings of which determine how the channel will operate.
  • Page 127 Appendix C NR4 Configuration Worksheet 3. Determine the desired state for the channel data word if an open or short circuit (RTD only) condition is detected for that channel. Enter the 2–digit binary code in bit field 6–7 of the channel configuration word. Select Broken Input Bits 6 and 7...
  • Page 128 Appendix C NR4 Configuration Worksheet 8. If you have selected scaled–for–PID or proportional counts data formats, you can choose module defined scaling (this applies the scale associated with your data format selection in step 2). In addition, use bits 13 and 14 if you want to define the scaling range yourself for proportional counts data format (user–set scaling).
  • Page 129 Appendix C NR4 Configuration Worksheet Channel Configuration Worksheet É É É Bit Number É É É É É É Channel 0 Channel 1 Channel 2 Channel 3 Input Type Select Data Format Select Broken Input Select Temperature Units Select Filter Frequency Select Channel Enable Excitation Current Select Scaling Select...
  • Page 130 Index RTD/resistance Input Module User Manual filter frequency, 4–3 effects on noise filtering, 4–3 A/D, P–4 effects on update time, 4–3 abbreviations, P–4 channel status bit, 5–22 addressing, 4–2 bit description in status word, 5–22 configuration word, 4–2 channel timing addressing example, 4–2 channel scan time, 4–9 data word, 4–3...
  • Page 131 Index RTD/resistance Input Module User Manual dynamic channel configuration, 6–4 full scale range, P–5 effective resolution gain drift, P–5 as a function of filter frequency, 4–5 gain error, P–5 definition, P–5 See also full scale error electrical noise, 3–2 getting started. See quick start guide electrical specifications, A–1 grounding Electrostatic damage, 3–2...
  • Page 132 Index RTD/resistance Input Module User Manual LSB, P–5 accuracy, 1–5, A–5 ohmic values, 1–5, A–5 repeatability, 1–5, A–5 resolution, 1–5, A–5 wiring diagram, 3–10, 3–11 manuals, related, P–3 wiring inputs, 3–9, 3–12 module accuracy, A–3 power requirements, 3–2 module ID code, 4–1 power–up sequence, 1–8 how to enter, 4–1 programming, 6–1...
  • Page 133 Index RTD/resistance Input Module User Manual temperature drift, 1–4 bit description in status word, 5–21 temperature ranges, 1–3, A–3 terminal pinout diagram, 3–6 terminal wiring terminal wiring, 3–6 2–wire RTD interconnection, 3–8 terms, P–4 3–wire RTD interconnection, 3–8 4–wire RTD interconnection, 3–8 tools required for installation, 2–1 theory, 1–1 torque, 3–7...
  • Page 134 Rico Qatar Romania Russia–CIS Saudi Arabia Singapore Slovakia Slovenia South Africa, Republic Spain Sweden Switzerland Taiwan Thailand Turkey United Arab Emirates United Kingdom United States Uruguay Venezuela Yugoslavia Allen-Bradley Headquarters, 1201 South Second Street, Milwaukee, WI 53204 USA, Tel: (1) 414 382-2000 Fax: (1) 414 382-4444 Publication 1746-6.7 – June 1998 40072-007-01(C) I–1...

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