PSH32-TC6 SHIELDED CABLE WITH THERMOCOUPLE MINICONNECTORS INSTALLATION GUIDE This installation guide describes how to install and connect thermocouples and digital I/O signals to the PSH32-TC6 shielded cable with thermocouple miniconnectors for use with the NI PCMCIA-4350. Introduction The PSH32-TC6 shielded cable with thermocouple miniconnectors consists of a pod with six miniconnectors that connect the thermocouples to the NI PCMCIA-4350. This pod connects to the NI PCMCIA-4350 input/output (I/O) connector with a shielded cable. You also can access the four digital I/O (DIO) lines and digital ground of the NI PCMCIA-4350 using the detachable screw terminal connector located on the pod. This cable is designed specifically for ease of use with thermocouples. The cable features isothermal construction to minimize the temperature gradients across the thermocouple junctions and a high-accuracy thermistor cold-junction temperature sensor. The pod provides connections to all NI PCMCIA-4350 DIO lines and to all but two analog input channels (CH). CH0 is dedicated to the cold-junction sensor, and CH1 is dedicated to auto-zeroing circuitry. Refer to the NI 435X User Manual for further details about these two channels. National Instruments™, NI™, ni.com™, and NI-DAQ™ are trademarks of National Instruments Corporation. Product and company names mentioned herein are trademarks or trade names of their respective companies. For patents covering National Instruments products, refer to the appropriate location: Help»Patents in your software, the patents.txt file on your CD, or ni.com/patents. ni.com © 1997–2002 National Instruments Corp. All rights reserved. September 2002 321637C-01 Conventions The following conventions are used in this guide: » The » symbol leads you through nested menu items and dialog box options to a final action. The sequence File»Page Setup»Options directs you to pull down the File menu, select the Page Setup item, and select Options from the last dialog box. This icon denotes a note, which alerts you to important information. This icon denotes a caution, which advises you of precautions to take to avoid injury, data loss, or a system crash. When this symbol is marked on the product, refer to the Read Me First: Safety and Radio-Frequency Interference document, shipped with the product, for precautions to take. italic Italic text denotes variables, emphasis, a cross reference, or an introduction to a key concept. This font also denotes text that is a placeholder for a word or value that you must supply. monospace Text in this font denotes text or characters that you should enter from the keyboard, sections of code, programming examples, and syntax examples. This font is also used for the proper names of disk drives, paths, directories, programs, subprograms, subroutines, device names, functions, operations, variables, filenames and extensions, and code excerpts. NI 435X Refers to all devices in the National Instruments 4350 and 4351 families. What You Need to Get Started You need the following items to set up and use the PSH32-TC6: ❑ PSH32-TC6 shielded cable with thermocouple miniconnectors ❑ PSH32-TC6 Shielded Cable with Thermocouple Miniconnectors Installation Guide ❑ NI PCMCIA-4350 and documentation ❑ Read Me First: Safety and Radio-Frequency Interference ❑ Thermocouple with a miniconnector ❑ 1/8 in. flathead screwdriver ❑ Wire cutter PSH32-TC6 Shielded Cable Installation Guide 2 ni.com ❑ Wire insulation stripper ❑ Adhesive hook-and-loop fastener strip Connecting the Signals Refer to the NI 435X User Manual for signal connection examples. Connecting Thermocouples Refer to the Read Me First: Safety and Radio-Frequency Interference document before removing equipment covers or connecting/disconnecting any signal wires. Caution Insert the thermocouple miniconnector to the mating miniconnector on the thermocouple pod, as shown in Figure 1. Each miniconnector is keyed; that is, it has two spades of different widths so that you can insert the thermocouple in only one way. Do not force the miniconnector; if you encounter difficulty while inserting the miniconnector, check whether the polarity is correct. Connecting DIO Signals Refer to Figure 1 as you complete the following steps to connect the digital signals to the PSH32-TC6: 1. Use a wire cutter and wire insulation stripper to strip the wire ends as necessary to connect them to the screw terminals. 2. Loosen the screws in the screw terminals with the 1/8 in. flathead screwdriver. 3. Insert the stripped wires into the screw terminals. Tighten the screws with the 1/8 in. flathead screwdriver. The wires should be firmly connected. © National Instruments Corporation 3 PSH32-TC6 Shielded Cable Installation Guide 2 3 1 4 5 6 1 0 2 1 3 -Z uto :A r 1 2 nso 4 Se n 7 tio 3 nc -Ju old 3 0 0: C 6 n I O I D alog An 2 5 2 5 - + ero 4 3 6 - + 7 7 - + - + + + 8 9 1 2 3 Ejector Ears NI PCMCIA-4350 Connector Screw Terminals for DIO 4 5 6 Screw Terminal Receptacle Thermocouple Pod Label 7 8 9 Miniconnector Receptacles Miniconnector Thermocouple Figure 1. PSH32-TC6 Parts Locator Diagram Connecting to the PSH32-TC6 to the NI PCMCIA-4350 Attach the connector end of the PSH32-TC6 cable to the NI PCMCIA-4350 I/O connector, as shown in Figure 2. The two connectors should snap together. To disconnect the cable from the NI PCMCIA-4350, press inward on the two ejector ears on the cable backshell and gently pull on the backshell. The cable should pop out. Do not pull the cable. You can use the adhesive hook-and-loop fastener to attach the thermocouple receptacle end of the cable to any flat surface. To minimize the temperature gradient inside the thermocouple pod and maintain its isothermal nature for accurate cold-junction compensation, place the PSH32-TC6 away from extreme temperature differentials. Note PSH32-TC6 Shielded Cable Installation Guide 4 ni.com The connectors of both the NI PCMCIA-4350 and the PSH32-TC6 are keyed. You can attach them in only one way. Do not force the cable when inserting it into or removing it from the NI PCMCIA-4350 connector. If you encounter difficulty, check whether the polarity is correct. Caution 1 2 3 4 5 1 0 2 1 ero 3 to-Z 3 1: Au 2 nsor 4 n Se 7 ctio un ld-J3 0 0: Co 6 DIO alog In An 2 5 2 5 1 2 Portable Computer PCMCIA Slot 3 4 NI PCMCIA-4350 PSH32-TC6 Shielded Cable 5 - + 4 3 6 - + 7 - + - + + + NI PCMCIA-4350 I/O Connector Figure 2. Connecting the Cable Assembly to the NI PCMCIA-4350 Cold-Junction Temperature Sensor The PSH32-TC6 cold-junction temperature sensor consists of a precision thermistor excited by the 25 µA current source on the NI PCMCIA-4350. At 25 °C, the resistance of the thermistor is 5,000 Ω. The thermistor resistance varies from 16,305 to 1,492 Ω over the 0 to 55 °C temperature range. The corresponding sensor output voltage varies from 408 to 37 mV over this temperature range. To select and measure the temperature sensor, refer to the data acquisition software documentation for programming information. © National Instruments Corporation 5 PSH32-TC6 Shielded Cable Installation Guide Alternatively, you can use the following formulas to convert the cold-junction sensor voltage to cold-junction temperature: T(°C) = TK – 273.15 where TK is the temperature in Kelvin. 1 T K = ---------------------------------------------------------------3a + b • ln R T + c • ( ln R T ) a = 1.295361 × 10 –3 b = 2.343159 × 10 –4 c = 1.018703 × 10 –7 RT = resistance of the thermistor in ohms T ( °C ) • 9 T ( °F ) = ------------------------ + 32 5 where T(°F) and T(°C) are the temperature readings in degrees Fahrenheit and degrees Celsius, respectively. When you have configured the NI 435X device with the correct accessory in Measurement & Automation Explorer (MAX), NI-DAQ can automatically perform cold-junction compensation on measurements taken on thermocouple channels. Note Specifications Cold-junction sensor accuracy1 ..............0.06 °C from 15 to 35 °C; 0.2 °C from 0 to 15 °C and 35 to 55 °C Maximum working voltage2 (signal plus common mode) ...................Each input should remain within ±42 V of ground 1 2 Includes only the thermistor accuracy. The combined effects of the temperature sensor accuracy, as well as the current source accuracy due to tolerances in all components in the NI PCMCIA-4350, the effects caused by temperature and loading, and self-heating and current leakage are discussed in the NI 435X User Manual. Refer to the NI PCMCIA-4350 maximum working voltage specification in Appendix A, Specifications, of the NI 435X User Manual; use the lower number of the two. PSH32-TC6 Shielded Cable Installation Guide 6 ni.com Technical Support Resources NI Web Support NI Web support is your first stop for help in solving installation, configuration, and application problems and questions. Online problem-solving and diagnostic resources include frequently asked questions, knowledge bases, product-specific troubleshooting wizards, manuals, drivers, software updates, and more. Web support is available through the Technical Support section of ni.com. Worldwide Support NI has offices located around the world to help address your support needs. You can access our branch office Web sites from the Worldwide Offices section of ni.com. Branch office Web sites provide up-to-date contact information, support phone numbers, email addresses, and current events. If you have searched the technical support resources on our Web site and still cannot find the answers you need, contact your local office or NI corporate. For telephone support in the United States, dial 512 795 8248. 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