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SLC 500 Thermocouple/mV Analog
Input Module
(Catalog Number 1746-NT8)
Installation Instructions
Inside...
Important User Information . . . . . . . . . . . . . . . . . . . . . . . . . 2
For More Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Module Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Input Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Hardware Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Installing And Wiring Your Module . . . . . . . . . . . . . . . . . . . 8
Electrostatic Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Required Tools and Equipment. . . . . . . . . . . . . . . . . . . . . . 9
Power Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Considerations for a Modular System . . . . . . . . . . . . . . . . . 10
Considerations for a Fixed Controller . . . . . . . . . . . . . . . . . 10
Selecting A Rack Slot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Module Installation and Removal . . . . . . . . . . . . . . . . . . . . 11
Terminal Block Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Cold Junction Compensation (CJC) . . . . . . . . . . . . . . . . . . 13
Wiring Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Thermocouple Junctions . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Preparing and Wiring the Cables . . . . . . . . . . . . . . . . . . . . 18
Module Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Publication 1746-5.23
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Related Manuals for Allen-Bradley SLC 500 1746-NT8
Summary of Contents for Allen-Bradley SLC 500 1746-NT8
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Page 1: Table Of Contents
SLC 500 Thermocouple/mV Analog Input Module (Catalog Number 1746-NT8) Installation Instructions Inside... Important User Information ......2 For More Information. -
Page 2: Important User Information
Since there are many variables and requirements associated with any particular installation, Allen-Bradley does not assume responsibility or liability (to include intellectual property liability) for actual use based upon the examples shown in this publication. -
Page 3: For More Information
SLC 500 Thermocouple/mV Analog Input Module For More Information As part of our effort to preserve, protect, and improve our environment, Allen- Bradley is reducing the amount of paper we use. Less paper means more options for you. In addition to traditional printed publications and CD-ROM versions, we now offer on-line manuals with the most up-to-date information you can get. -
Page 4: Module Overview
SLC 500 Thermocouple/mV Analog Input Module Module Overview The module communicates with the SLC 500 processor and receives +5V dc and +24V dc power from the system power supply through the parallel backplane interface. No external power supply is required. You may install as many thermocouple modules in the system as the power supply can support. -
Page 5: Input Ranges
SLC 500 Thermocouple/mV Analog Input Module Input Ranges The following tables define thermocouple types and associated temperature ranges and the millivolt analog input signal ranges that each of the module’s input channels will support. To determine the practical temperature range of your thermocouple, refer to the specifications in Appendix A of the SLC 500 Thermocouple/mV Analog Input Module User Manual, publication 1746-6.22. -
Page 6: Hardware Features
SLC 500 Thermocouple/mV Analog Input Module Hardware Features The module fits into any single slot (other than slot 0) for I/O modules 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). - Page 7 SLC 500 Thermocouple/mV Analog Input Module 1746-NT8 Features Channel Status INPUT LEDs (Green) CHANNEL Door Label STATUS Module Status MODULE THERMOCOUPLE/mV LED (Green) 1746-NT8 CJC A+ CJC A- Removable CHL 0+ CHL 0- Terminal Block SHIELD CHL 1+ CHL 1- CHL 2+ CHL 2- SHIELD...
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Page 8: Installing And Wiring Your Module
SLC 500 Thermocouple/mV Analog Input Module Installing And Wiring Your Module Read this section to install and wire your module. This section covers: • avoiding electrostatic damage • determining power requirements • installing the module • wiring signal cables to the module’s terminal block Electrostatic Damage Electrostatic discharge can damage semiconductor devices inside this module if you touch backplane connector pins. -
Page 9: Required Tools And Equipment
SLC 500 Thermocouple/mV Analog Input Module Required Tools and Equipment Have the following tools and equipment ready: • 2.5 mm (0.1 in.) slot-head screwdriver • thermocouple or millivolt sensor • appropriate thermocouple extension wire (if needed) • thermocouple/mV input module (1746-NT8) •... -
Page 10: Considerations For A Modular System
SLC 500 Thermocouple/mV Analog Input Module Considerations for a Modular System Place your module in any slot of an SLC 500 modular, or modular expansion chassis, except for the left-most slot (slot 0) reserved for the SLC processor or adapter modules. Considerations for a Fixed Controller The power supply in the 2-slot SLC 500 fixed I/O chassis (1746-A2) can support only specific combinations of modules. -
Page 11: Module Installation And Removal
3. Slide your module into the chassis until both top and bottom retaining clips are secure. Apply firm even pressure on your module to attach it to its backplane connector. Never force your module into the slot. 4. Cover all unused slots with the Card Slot Filler, Allen-Bradley part number 1746-N2. Publication 1746-5.23... -
Page 12: Terminal Block Removal
SLC 500 Thermocouple/mV Analog Input Module Terminal Block Removal To remove the terminal block: 1. Loosen the two terminal block release screws. To avoid cracking the terminal block, alternate between screws as you remove them. 2. Using a screwdriver or needle-nose pliers, carefully pry the terminal block loose. -
Page 13: Cold Junction Compensation (Cjc)
SLC 500 Thermocouple/mV Analog Input Module Cold Junction Compensation (CJC) To obtain accurate readings from each of the channels, the cold-junction temperature (temperature at the module’s terminal junction between the thermocouple wire and the input channel) must be compensated for. Two cold junction compensating sensors are integrated in the removable terminal block. -
Page 14: Wiring Guidelines
SLC 500 Thermocouple/mV Analog Input Module Wiring Guidelines Isolation 7KH 17 PRGXOH SURYLGHV WKH IROORZLQJ HOHFWULFDO LVRODWLRQ • 12.5V dc electrical isolation channel to channel • 500V dc electrical isolation channel to chassis ground • 500V dc electrical isolation channel to backplane Care must be taken when choosing a thermocouple type and connecting it to the 1746-NT8 module from the environment being measured. - Page 15 SLC 500 Thermocouple/mV Analog Input Module Grounded Junction Thermocouples As shown in the following illustration, the shield input terminals are internally connected together, which are then connected to chassis ground. Using grounded junction thermocouples with electrically conductive sheaths removes the thermocouple signal to chassis ground isolation of the module.
- Page 16 SLC 500 Thermocouple/mV Analog Input Module Exposed Junction Thermocouples 5HFRPPHQGHG ZLULQJ IRU H[SRVHG MXQFWLRQ WKHUPRFRXSOHV LV VKRZQ LQ WKH IROORZLQJ LOOXVWUDWLRQ 8VLQJ H[SRVHG MXQFWLRQ WKHUPRFRXSOHV PD\ UHVXOW LQ UHPRYDO RI FKDQQHOWRFKDQQHO LVRODWLRQ 7KLV PD\ RFFXU LI PXOWLSOH H[SRVHG WKHUPRFRXSOHV DUH LQ GLUHFW FRQWDFW ZLWK HOHFWULFDOO\ FRQGXFWLYH SURFHVV PDWHULDOV 7R SUHYHQW YLRODWLRQ RI FKDQQHOWRFKDQQHO LVRODWLRQ ‡...
- Page 17 SLC 500 Thermocouple/mV Analog Input Module Cable Wiring Considerations Follow these guidelines to wire your input signal cables: • Power, input, and output (I/O) wiring must be in accordance with Class 1, Division 2 wiring methods [Article 501-4(b) of the National Electrical Code, NFPA 70] and in accordance with the authority having jurisdiction.
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Page 18: Preparing And Wiring The Cables
SLC 500 Thermocouple/mV Analog Input Module Preparing and Wiring the Cables To prepare and connect cable leads and drain wires, follow these steps: Cable (Remove foil shield Signal Wires and drain wire from sensor-end of the cable.) Drain Wire Signal Wires 1. - Page 19 SLC 500 Thermocouple/mV Analog Input Module 6. Connect the signal wires of each channel to the terminal block. Important: Only after verifying that your connections are correct for each channel, trim the lengths to keep them short. Avoid cutting leads too short. 7.
- Page 20 SLC 500 Thermocouple/mV Analog Input Module Terminal Block Diagram with Input Cable CJC A+ CJC A- Channel 0+ Thermocouple or mV Cable Channel 0- Shield for CH0 and CH1 Channel 1+ Channel 1- Channel 2+ Channel 2- Shield for CH2 and CH3 Channel 3+ Channel 3- Channel 4+...
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Page 21: Module Specifications
SLC 500 Thermocouple/mV Analog Input Module Module Specifications Electrical Specifications Backplane Current Consumption 120 mA at 5V dc, 70 mA at 24V dc Backplane Power Consumption 2.28W maximum (0.5W at 5V dc, 1.68W at 24V dc) Number of Channels 8 (backplane and channel-to-channel isolated) I/O Chassis Location Any I/O module slot except 0 A/D Conversion Method... - Page 22 SLC 500 Thermocouple/mV Analog Input Module Physical Specifications 9 green status indicators, one for each of 8 LED Indicators channels and one for module status Module ID Code 3533 One 14 AWG wire or two 22 AWG wires per Maximum Wire Size terminal Environmental Specifications Operating Temperature...
- Page 23 SLC 500 Thermocouple/mV Analog Input Module Input Specifications Thermocouple Type J -210°C to +760 C (-346°F to +1400°F) Thermocouple Type K -270°C to +1370°C (-454°F to +2498°F) Thermocouple Type T -270°C to +400°C (-454°F to +752°F) Thermocouple Type E -270°C to +1000°C (-454°F to +1832°F) Thermocouple Type R 0°C to +1768°C...
- Page 24 Publication 1746-5.23 - June 1999 40071-064-01(A) © 1999 Rockwell International. All Rights Reserved. Printed in USA...
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