USB-TC User's Guide - from Measurement Computing
Contents
1. Bold text is used for the names of objects on a screen such as buttons text boxes and check boxes italic text Italic text is used for the names of manuals and help topic titles and to emphasize a word or phrase Where to find more information Additional information about USB TC hardware is available on our website at www mccdaq com You can also contact Measurement Computing Corporation by phone fax or email with specific questions Knowledgebase kb mccdaq com Phone 508 946 5100 and follow the instructions for reaching Tech Support Fax 508 946 9500 to the attention of Tech Support Email techsupportmccdag com Chapter 1 Introducing the USB TC Overview USB TC features The USB TC is a USB 2 0 full speed thermocouple input module that is supported under popular Microsoft Windows operating systems The USB TC is fully compatible with both USB 1 1 and USB 2 0 ports The USB TC provides eight differential thermocouple input channels Eight independent TTL compatible digital I O channels are provided to monitor TTL level inputs communicate with external devices and to generate alarms The digital I O channels are software programmable for input or output With the USB TC you can take measurements from type J K R S T N E and B thermocouples The USB TC provides two integrated cold junction compensation CJC sensors for thermocouple measurements An open thermocouple detection feature l2. Phone 508 946 5100 and follow the instructions for reaching Tech Support Fax 508 946 9500 to the attention of Tech Support Email techsupport mccdaq com For international customers contact your local distributor Refer to the International Distributors section on our website at www mccdaq com International Installing the software Refer to the Quick Start Guide for instructions on installing the software on the MCC DAQ CD This booklet is available in PDF at www mccdaq com PDFmanuals DAQ Software Quick Start pdf Installing the hardware To connect the USB TC to your system turn your computer on and connect the USB cable to a USB port on your computer or to an external USB hub that is connected to your computer The USB cable provides power and communication to the USB TC When you connect the USB TC to a computer for the first time a Found New Hardware dialog opens when the operating system detects the device When the dialog closes the installation is complete The USB LED should blink and then remain on This indicates that communication is established between the USB TC and your computer Caution Do not disconnect any device from the USB bus while the computer is communicating with the USB TC or you may lose data and or your ability to communicate with the USB TC USB TC User s Guide Installing the USB TC If the LED turns off If the LED is on but then turns off the computer has lost communication with
3. eet E S ODE UR UE ice e E ED EP Rt ee Rh Data line riz tioti rie tereti erp eee ret enn Open thermocouple detection OTD USB connectot nre TREE rere pee A E ap LED z iE a REHI HM POWet sass Sih epee SER pueden aUe ei BREVE 14 Chapter 5 olele itor Lio nI Senan E E id tin Delia 15 Analog Ipute eee et eee oie e eite ete eite o eed 15 Channel configurations vse cls ah lie BANA AB I He i TA sd eee REAR ee 15 ACCUTAC Vid E EE 16 Thermocouple measurement accuracy arrn rieri eene nennen nennen arer Eeoa thee ESAS E E REO IES 16 Thbroughput r te 2 nacen eene a es ek Se eee 16 Digital input outpUut reo Re FUSE RH EI EHE ORE FEE E PAPERI PERES rep ere RR deae Ere 17 USB TC User s Guide Mem 17 Microcontro lluita 17 USB WSV Voltage ens A R S E N 17 A O a NN RA 18 USB Specifications uri ad is 18 Environment 18 Mechanical ii AR 18 Signal CoBnector i oe ai 19 Declaration of CON OrM I V a cta Credis aida 20 Preface About this User s Guide This user s guide describes the Measurement Computing USB TC data acquisition device and lists device specifications Conventions in this user s guide For more information Text presented in a box signifies additional information related to the subject matter Caution Shaded caution statements present information to help you avoid injuring yourself and others damaging your hardware or losing your data bold text
4. input You can connect up to eight thermocouples to the differential sensor inputs COH COL to C7H C7L The device supports type J K R S T N E and B thermocouples CJC sensors The USB TC has two built in high resolution temperature sensors One sensor is located on the right side of the package and one sensor is located at the left side 10 USB TC User s Guide Sensor Connections Digital I O You can connect up to eight digital I O lines to the screw terminals labeled DIOO to DIO7 Each terminal is software configurable for input or output Power output The two 5V terminals are isolated 500 VDC from the USB 5V Caution Each 5V terminal is an output Do not connect to an external power supply or you may damage the USB TC and possibly the computer Ground The six analog ground terminals GND provide a common ground for the input channels and DIO bits and are isolated 500 VDC from the USB GND Thermocouple connections A thermocouple consists of two dissimilar metals that are joined together at one end When the junction of the metals is heated or cooled a voltage is produced that correlates to temperature The USB TC makes fully differential thermocouple measurements without the need of ground referencing resistors A 32 bit floating point value in either a voltage or temperature format is returned by software An open thermocouple detection feature is available for each analog input which automatically dete
5. of I O 8 DIOO through DIO Configuration Independently configured for input or output Power on reset is input mode Pull up pull down configuration All pins pulled up to 5 V via 47 K resistors default Pull down to ground GND also available Digital I O transfer rate software paced Digital input 50 port reads or single bit reads per second typ m Digital output 100 port writes or single bit writes per second typ Input high voltage 2 0 V min 5 5 V absolute max Input low voltage 0 8 V max 0 5 V absolute min Output low voltage 0 7 V max IOL z 2 5 mA Output high voltage 3 8 V min IOH 2 5 mA Note 7 All ground pins are isolated from earth ground If a connection is made to earth ground when using digital I O and conductive thermocouples the thermocouples are no longer isolated In this case thermocouples must not be connected to any conductive surfaces that may be referenced to earth ground Memory Table 6 Memory specifications Parameter Specification EEPROM 1 024 bytes isolated micro reserved for sensor configuration 256 bytes USB micro for external application use Microcontroller Table 7 Microcontroller specifications Parameter Specification Type Two high performance 8 bit RISC microcontrollers USB 5V voltage Table 8 USB 5V voltage specifications Parameter Specification USB 5V VBUS input voltage range 4 75
6. the USB TC To restore communication disconnect the USB cable from the computer and then reconnect it This should restore communication and the LED should turn back on Configuring the hardware All hardware configuration options on the USB TC are programmable with software Use InstaCal to set the thermocouple type for each channel pair Configuration options are stored on the USB TC s isolated microcontroller in EEPROM which is non volatile memory on the USB TC module Configuration options are loaded on power up The factory default configuration is Type J thermocouple Warm up Allow the USB TC to warm up for 30 minutes before taking measurements This warm up time minimizes thermal drift and achieves the specified rated accuracy of measurements Calibrating the hardware The USB TC is fully calibrated via InstaCal Allow a 30 minute warm up before calibrating Chapter 3 Sensor Connections The USB TC supports type J K R S T N E and B thermocouples Thermocouple selection The thermocouple type you select will depend on your application needs Review the temperature ranges and accuracies of each type to determine which is best suited for your application Screw terminal pinout The USB TC has four rows of screw terminals two rows on the top edge of the housing and two rows on the bottom edge Each row has 26 connections Between each bank of screw terminals are two integrated CJC sensors us
7. the thermocouple length If you need to increase the length of your thermocouple use the same type of thermocouple wires to minimize the error introduced by thermal EMFs Data linearization After the CJC correction is performed on the measurement data an on board microcontroller automatically linearizes the thermocouple measurement data using National Institute of Standards and Technology NIST linearization coefficients for the selected thermocouple type The measurement data is then output as a 32 bit floating point value in the configured format voltage or temperature Open thermocouple detection OTD The USB TC is equipped with an open thermocouple detection for each analog input channel With OTD any open circuit or short circuit condition at the thermocouple sensor is detected by the software An open channel is detected by driving the input voltage to a negative value outside the range of any thermocouple output The software recognizes this as an invalid reading and flags the appropriate channel The software continues to sample all channels when OTD is detected Input leakage current With open thermocouple detection enabled 105 nA max of input leakage current is injected into the thermocouple This current can cause an error voltage to develop across the lead resistance of the thermocouple that is indistinguishable from the thermocouple voltage you are measuring You can estimate this error voltage with the following f
8. Group 1 Class A EN 55011 2007 CISPR 11 2003 Conducted emissions Group 1 Class A Immunity EN 61326 1 2006 Table 3 EC 61000 4 2 2001 Electrostatic Discharge immunity EC 61000 4 3 2002 Radiated Electromagnetic Field immunity To maintain compliance to the standards of this declaration the following conditions must be met The host computer peripheral equipment power sources and expansion hardware must be CE compliant All I O cables must be shielded with the shields connected to ground Ocables must be less than 3 meters 9 75 feet in length The host computer must be properly grounded The host computer must be USB 2 0 compliant Equipment must be operated in a controlled electromagnetic environment as defined by Standards EN 61326 1 2006 or IEC 61326 1 2005 Note Data acquisition equipment may exhibit noise or increased offsets when exposed to high RF fields gt 1V m or transients Declaration of Conformity based on tests conducted by Chomerics Test Services Woburn MA 01801 USA in April 2005 Test records are outlined in Chomerics Test Report EMI4193 05 Further testing was conducted by Chomerics Test Services Woburn MA 01801 USA in December 2008 Test records are outlined in Chomerics Test Report EMI5215B 08 We hereby declare that the equipment specified conforms to the above Directives and Standards lax hogg Carl Haapaoja Director of Quality Assurance Measu
9. O boards face some harsh environments some harsher than the boards are designed to withstand Contact MCC to determine your product s eligibility for this program 30 Day Money Back Guarantee Any Measurement Computing Corporation product may be returned within 30 days of purchase for a full refund of the price paid for the product being returned If you are not satisfied or chose the wrong product by mistake you do not have to keep it These warranties are in lieu of all other warranties expressed or implied including any implied warranty of merchantability or fitness for a particular application The remedies provided herein are the buyer s sole and exclusive remedies Neither Measurement Computing Corporation nor its employees shall be liable for any direct or indirect special incidental or consequential damage arising from the use of its products even if Measurement Computing Corporation has been notified in advance of the possibility of such damages Trademark and Copyright Information Measurement Computing Corporation InstaCal Universal Library and the Measurement Computing logo are either trademarks or registered trademarks of Measurement Computing Corporation Refer to the Copyrights amp Trademarks section on mccdaq conylegal for more information about Measurement Computing trademarks Other product and company names mentioned herein are trademarks or trade names of their respective companies O 2014 Measurement Computing Corp
10. USB TC Thermocouple Measurement User s Guide Document Revision 9 January 2014 Vi N FA MEASUREMENT O Copyright 2014 4 N Va COMPUTING Your new Measurement Computing product comes with a fantastic extra Management committed to your satisfaction Thank you for choosing a Measurement Computing product and congratulations You own the finest and you can now enjoy the protection of the most comprehensive warranties and unmatched phone tech support It s the embodiment of our mission To provide data acquisition hardware and software that will save time and save money Simple installations minimize the time between setting up your system and actually making measurements We offer quick and simple access to outstanding live FREE technical support to help integrate MCC products into a DAQ system Limited Lifetime Warranty Most MCC products are covered by a limited lifetime warranty against defects in materials or workmanship for the life of the product to the original purchaser unless otherwise noted Any products found to be defective in material or workmanship will be repaired replaced with same or similar device or refunded at MCC s discretion For specific information please refer to the terms and conditions of sale Harsh Environment Program Any Measurement Computing product that is damaged due to misuse or any reason may be eligible for replacement with the same or similar device for 50 of the current list price I
11. V min to 5 25 V max 17 USB TC User s Guide Specifications Power Table 9 Power specifications Parameter Condition Specification Supply current USB enumeration lt 100 mA Supply current Continuous mode 140 mA typ Note 8 User 5V output voltage range Connected to self powered hub Note 9 4 75 V min to pins 21 and 47 5 25 V max User 5V output current Bus powered and connected to a self powered hub Note 9 10 mA max pins 21 and 47 Isolation Measurement system to PC 500 VDC min Note 8 This is the total current requirement for the device which includes up to 10 mA for the status LED Note 9 Self Powered Hub refers to a USB hub with an external power supply Self powered hubs allow a connected USB device to draw up to 500 mA Root Port Hubs reside in the PC USB Host Controller The USB port s on your PC are root port hubs All externally powered root port hubs desktop PC s provide up to 500 mA of current for a USB device Battery powered root port hubs provide 100 mA or 500 mA depending upon the manufacturer A laptop PC that is not connected to an external power adapter is an example of a battery powered root port hub USB specifications Table 10 USB specifications Parameter Specification USB device type USB 2 0 full speed Device compatibility USB 1 1 USB 2 0 Device power capability Self powered 100 mA consumption max USB cab
12. cts an open or broken thermocouple Use InstaCal to select the thermocouple type J K R S T N E and B and one or more sensor input channels to connect the thermocouple Wiring configuration Connect the thermocouple to the USB TC using a differential configuration as shown in Figure 3 Q Q eO gt o qu cm a QOS3E3SOCQO3E3E ZO ASA AO oooooooooo Figure 3 Typical thermocouple connection Connect thermocouples to the USB TC such that they are floating with respect to GND pins 9 19 28 38 The USB TC GND pins are isolated from earth ground so connecting thermocouple sensors to voltages referenced to earth ground is permissible as long as the isolation between the GND pins 9 19 28 38 and earth ground is maintained When thermocouples are attached to conductive surfaces the voltage differential between multiple thermocouples must remain within 1 4 V For best results we recommend the use of insulated or ungrounded thermocouples when possible Maximum input voltage between analog input and ground The absolute maximum input voltage between an analog input and the isolated GND pins is 25 VDC when the device is powered on and 40 VDC when the device is powered off If you need to increase the length of your thermocouple use the same type of thermocouple wires to minimize the error introduced by thermal EMFs 11 USB TC User s Guide Sensor Connections Digital I O connections You can connect u
13. e configuration is made non volatile through the use of the EEPROM Note 2 The factory default configuration is Type J 15 USB TC User s Guide Specifications Accuracy Thermocouple measurement accuracy Table 3 Thermocouple accuracy specifications including CJC measurement error Sensor Type Maximum error C Typical error C Temperature range C J 1 499 30 507 210 to 0 0 643 0 312 0 to 1200 K 1 761 0 538 210 to 0 0 691 0 345 0 to 1372 S 2 491 0 648 50 to 250 1 841 0 399 250 to 1768 1 R 2 653 0 650 50 to 250 1 070 20 358 250 to 1768 1 B 1 779 20 581 250 to 700 0 912 0 369 700 to 1820 E 1 471 0 462 200 to 0 0 639 0 245 0 to 1000 T 1 717 0 514 200 to 0 0 713 20 256 0 to 600 N 1 969 30 502 200 to 0 0 769 0 272 0 to 1300 Note 3 Thermocouple specifications include linearization cold junction compensation and system noise These specs are for one year or 3000 operating hours whichever comes first and for operation of the device between 15 C and 35 C For measurements outside this range add 0 5 degree to the maximum error shown There are CJC sensors on each side of the module The accuracy listed above assumes the screw terminals are at the same temperature as the CJC sensor Errors shown do not include inherent thermocouple error Please contact your thermocouple supplier for de
14. ed for thermocouple measurements Signals are identified in Figure 2 Reserved RSVD 1 4G S Reserved No connection NC 2 8 GS Ground CHO sensor input coH 3599 8 CH7 sensor input CHO sensor input co 4 MO S CH7 sensor input No connection Nc 5 WO S Reserved Reserved Rsvd 6 9 S No connection CH1 sensor input cH 7 MO 8 CH6 sensor input CH1 sensor input cui 8 NS S CH6 sensor input Ground GND 9 MOS 8 No connection Reserved rsvp 10 HO 8 Reserved CJC sensor W p Reserved RSVD 11 8 S Reserved No connection NC 12 S S Ground CH2 sensor input C2H 13 S S CH5 sensor input CH2 sensor input C2L 14 S S CH5 sensor input No connection NC 15 8 S Reserved Reserved RSVD 16 19 S No connection CH3 sensor input C3H 17 MO S CH4 sensor input CH3 sensor input C3L 18 98 GS CH4 sensor input Ground GND 19 O S No connection Reserved RSVD 20 9 S Reserved Power output 5V 21 8 8 Power output Ground GND 22 S GS Ground DIO channel 0 pio 23 O S DIO channel 7 DIO channel 1 Do 24 HO S DIO channel 6 DIO channel 2 DIO2 25 8 S DIO channel 5 DIO channel 3 DIO3 26 e 8 DIO channel 4 Figure 2 Screw terminal pinout Use 16 AWG to 30 AWG wire for your signal connections Tighten screw terminal connections When making connections to the screw terminals be sure to tighten the screw until tight Simply touching the top of the screw terminal is not sufficient to make a proper connection Thermocouple
15. el shifts the thermocouple s output voltage into the A D s common mode input range by applying 2 5 V to the thermocouple s low side at the C L input Always connect thermocouple sensors to the USB TC in a floating fashion Do not attempt to connect the thermocouple low side C L to GND or to a ground referencing resistor Cold junction compensation CJC When you connect the thermocouple sensor leads to the sensor input channel the dissimilar metals at the USB TC terminal blocks produce an additional thermocouple junction This junction creates a small voltage error term which must be removed from the overall sensor measurement using a cold junction compensation technique The measured voltage includes both the thermocouple voltage and the cold junction voltage To compensate for the additional cold junction voltage the USB TC subtracts the cold junction voltage from the thermocouple voltage The USB TC has two high resolution temperature sensors that are integrated into the design of the USB TC One sensor is located on the right side of the package and one sensor is located at the left side The CJC sensors measure the average temperature at the terminal blocks so that the cold junction voltage can be calculated A software algorithm automatically corrects for the additional thermocouples created at the terminal blocks by subtracting the calculated cold junction voltage from the analog input s thermocouple voltage measurement Increasing
16. ets you detect a broken thermocouple An on board microprocessor automatically linearizes the measurement data The USB TC is a standalone plug and play module which draws power from the USB cable No external power supply is required All configurable options are software programmable The USB TC is fully software calibrated Functional block diagram USB TC functions are illustrated in the block diagram shown here USB 2 0 Microcontroller Isolated Med 5V DC DC 500 V Isolation Barrier Figure 1 Functional block diagram Screw Terminal Screw Terminal USB TC User s Guide Introducing the USB TC Connecting a USB TC to your computer is easy Installing a data acquisition device has never been easier The USB TC relies upon the Microsoft Human Interface Device HID class drivers The HID class drivers ship with every copy of Windows that is designed to work with USB ports We use the Microsoft HID because it is a standard and its performance delivers full control and maximizes data transfer rates for your USB TC No third party device driver is required The USB TC is plug and play There are no jumpers to position DIP switches to set or interrupts to configure You can connect the USB TC before or after you install the software and without powering down your computer first When you connect an HID to your system your computer automatically detects it and configures the necessary software You ca
17. ification A D converters Four dual 24 bit Sigma Delta type Number of channels 8 differential Input isolation 500 VDC minimum between field wiring and USB interface Channel configuration Thermocouple sensor type Differential input voltage Thermocouple 0 080 V Absolute maximum input COx through C7x relative to 24 V power on voltage GND pins 9 19 28 38 24 V power off Input impedance 5 GQ min Input leakage current Open thermocouple detect enabled 105 nA max Normal mode rejection ratio Jin 60 Hz 90 dB min Common mode rejection ratio fin 50 Hz 60 Hz 100 dB min Resolution 24 bits No missing codes 24 bits Input coupling DC Warm up time 30 minutes min Open thermocouple detect Automatically enabled when the channel pair is configured for thermocouple sensors The maximum open detection time is 3 seconds CJC sensor accuracy 15 C to 35 C 0 25 C typ 0 5 C max 0 C to 70 C 1 0 to 0 5 C max Channel configurations Table 2 Channel configuration specifications Sensor Category Condition Specification Thermocouple J K S R B E T or N 8 differential channels Note 1 Channel configuration information is stored in the EEPROM of the isolated microcontroller by the firmware whenever any item is modified Modification is performed by commands issued over USB from an external application and th
18. le type A B cable UL type AWM 2723 or equivalent min 24 AWG VBUS GND min 28 AWG D D USB cable length 3 m 9 84 ft max Environmental Table 11 Environmental specifications Parameter Specification Operating temperature range 0 C to 70 C Storage temperature range 40 C to 85 C Humidity 0 to 90 non condensing Mechanical Table 12 Mechanical specifications Parameter Specification Dimensions L x W x H 128 52 x 88 39 x 35 56 mm 5 06 x 3 48 x 1 43 ft User connection length 3 m 9 84 ft max 18 USB TC User s Guide Specifications Signal connector Table 13 Signal connector specifications Parameter Specification Connector type Screw terminal Wire gauge range 16 AWG to 30 AWG Table 14 Screw terminal pinout Pin Signal Name Pin Description Pin Signal Name Pin Description 1 RSVD Reserved Do Not Use 27 RSVD Reserved Do Not Use 2 NC No connection 28 GND Ground 3 COH CHO sensor input 29 C7L CH7 sensor input 4 COL CHO sensor input 30 C7H CH7 sensor input 5 NC No connection 31 RSVD Reserved Do Not Use 6 RSVD Reserved Do Not Use 32 NC No connection 7 C1H CH1 sensor input 33 C6L CH6 sensor input 8 CiL CH1 sensor input 34 C6H CH6 sensor input 9 GND Ground 35 NC No con
19. n connect and power multiple HID peripherals to your system using a USB hub You can connect your system to various devices using a standard four wire cable The USB connector replaces the serial and parallel port connectors with one standardized plug and port combination You do not need a separate power supply module The USB automatically delivers the electrical power required by each peripheral connected to your system Data can flow two ways between a computer and peripheral over USB connections Chapter 2 Installing the USB TC What comes with your shipment The following items are shipped with the USB TC Hardware USB TC USB cable Software MCC DAQ CD Documentation In addition to this hardware user s guide you should also receive the Quick Start Guide This booklet provides an overview of the MCC DAQ software you received with the device and includes information about installing the software Please read this booklet completely before installing any software or hardware Unpacking As with any electronic device you should take care while handling to avoid damage from static electricity Before removing the USB TC from its packaging ground yourself using a wrist strap or by simply touching the computer chassis or other grounded object to eliminate any stored static charge If any components are missing or damaged contact us immediately using one of the following methods Knowledgebase kb mccdaq com
20. nection 10 RSVD Reserved Do Not Use 36 RSVD Reserved Do Not Use CJC sensor CJC sensor 11 RSVD Reserved Do Not Use 37 RSVD Reserved Do Not Use 12 NC No connection 38 GND Ground 13 C2H CH2 sensor input 39 C5L CH5 sensor input 14 C2L CH2 sensor input 40 C5H CH5 sensor input 15 NC No connection 41 RSVD Reserved Do Not Use 16 RSVD Reserved Do Not Use 42 NC No connection 17 C3H CH3 sensor input 43 C4L CHA sensor input 18 C3L CH3 sensor input 44 C4H CH4 sensor input 19 GND Ground 45 NC No connection 20 RSVD Reserved Do Not Use 46 RSVD Reserved Do Not Use 21 5V 5V output 47 5V 5V output 22 GND Ground 48 GND Ground 23 DIOO DIO channel 0 49 DIO7 DIO channel 7 24 DIO1 DIO channel 1 50 DIO6 DIO channel 6 25 DIO2 DIO channel 2 51 DIO5 DIO channel 5 26 DIO3 DIO channel 3 52 DIO4 DIO channel 4 19 Ce Declaration of Conformity Manufacturer Measurement Computing Corporation Address 10 Commerce Way Suite 1008 Norton MA 02766 USA Category Electrical equipment for measurement control and laboratory use Measurement Computing Corporation declares under sole responsibility that the product USB TC to which this declaration relates is in conformity with the relevant provisions of the following standards or other documents EC EMC Directive 2004 108 EC General Requirements EN 61326 1 2006 IEC 61326 1 2005 Emissions EN 55011 2007 CISPR 11 2003 Radiated emissions
21. ock diagram neon bte ie ueteri tette iet ege rete e ite oT reca deberes 6 Connecting a USB TC to your computer is easy oooocoocconnconcnononancnnnconoconoconocn nono no nn nono n entente trennen trennen rennen 7 Chapter 2 Installing the USB T G nirera so 8 What comes with your shipment sesessesssseeeseeeeeee nennen nennen een rennen enne tere tere trente entren trennen rennes 8 Hard WS RR EUG UI o REI URGERE IURI OUI WE ees Software Documentation Unpacking o onte o Deep Eb a EE ODER ees 8 Installing the A tp Ee ERE DH i E EH PER REED te hr e ete e 8 Instalhing the hardwate uote n oit ii 8 Configuring the hardware e Uere m ici RUMP ERES EUR 9 Calibrating the hardware ettet eei tete e eite in ree e Pete Pe eee eb diaria 9 Chapter 3 SENSO COMERCIOS tias 10 Screw terminal pimOut encia 10 Thermocouple input CIC sensors Digital I O Power output es Cround 5 iu en bu mene mme tide Th rtiocouple COrnhnectlons ac eerte test eerte Lee ee eO Eee E e ERR Re dean 11 Witing COMUN TIT 11 Digital O connections i uo E oett ii dec de OH EUREN 12 Chapter 4 Functional Details s Thermocouple measurements ci ois eerie de repeteret coe Pte pd e ee e e eene eye eee sedere deeem Cold junction compensation CIC terr
22. oration All rights reserved No part of this publication may be reproduced stored in a retrieval system or transmitted in any form by any means electronic mechanical by photocopying recording or otherwise without the prior written permission of Measurement Computing Corporation Notice Measurement Computing Corporation does not authorize any Measurement Computing Corporation product for use in life support systems and or devices without prior written consent from Measurement Computing Corporation Life support devices systems are devices or systems that a are intended for surgical implantation into the body or b support or sustain life and whose failure to perform can be reasonably expected to result in injury Measurement Computing Corporation products are not designed with the components required and are not subject to the testing required to ensure a level of reliability suitable for the treatment and diagnosis of people HM USB TC docx 2 Table of Contents Preface About this User s Guide oonnnnnicnnnnininccnnanacnna rincon 5 Conventions in this user s guide eerie sca itte e rH eee bed coiere Peli ete din rerba steuern 5 Where to find mote information cian aiii ee EEEE E EE KE aE S ea 3 Chapter 1 Introducing the US ETC eene cgacesceaetechtnevsstsentteesbenenenceenteesbanevenccesstscehtuedenuaressteesanedsuncees 6 Overview US B TC features ee ertet einen dut e 6 Functional bl
23. ormula error voltage resistance of the thermocouple x 105 nA To reduce the error reduce the length of the thermocouple to lower its resistance or lower the AWG of the wire by using a wire with a larger diameter With open thermocouple detection disabled 30 nA max of input leakage current is injected into the thermocouple 13 USB TC User s Guide Functional Details USB connector The USB connector provides 5V power and communication No external power supply is required LED The LED indicates the communication status of the USB TC It uses up to 5 mA of current The table below defines the function of the USB TC LED Illumination LED Indication Illumination Steady green The USB TC is connected to a computer or external USB hub Blinking green Data is being transferred Upon connection the LED blinks three times and then remains on this indicates a successful installation Power The two 5V terminals are isolated 500 VDC from the USB 5V Caution Each 5V terminal is an output Do not connect to an external power supply or you may damage the USB TC and possibly the computer 14 Chapter 5 Specifications All specifications are subject to change without notice Typical for 25 C unless otherwise specified Specifications in italic text are guaranteed by design Analog input Table 1 Generic analog input specifications range Parameter Condition Spec
24. p to eight digital I O lines to the screw terminals labeled DIOO to DIO7 You can configure each digital bit for either input or output All digital I O lines are pulled up to 5V with a 47 kQ resistor default You can request the factory to configure the resistor for pull down to ground if desired When you configure the digital bits for input you can use the USB TC digital I O terminals to detect the state of any TTL level input Refer to the schematic shown in Figure 4 If you set the switch to the 5V input DIOO reads TRUE 1 If you move the switch to GND DIOO reads FALSE 0 AT GND 5V Figure 4 Schematic showing switch detection by digital channel DIOO All ground pins are isolated from earth ground If a connection is made to earth ground when using digital I O and conductive thermocouples the thermocouples are no longer isolated In this case thermocouples must not be connected to any conductive surfaces that may be referenced to earth ground For general information regarding digital signal connections and digital I O techniques refer to the Guide to DAQ Signal Connections available on our web site at www mccdaq com signals signals pdf 12 Chapter 4 Functional Details Thermocouple measurements A thermocouple consists of two dissimilar metals that are joined together at one end When the junction of the metals is heated or cooled a voltage is produced that correlates to temperature The USB TC hardware lev
25. rement Computing Corporation 10 Commerce Way Suite 1008 Norton Massachusetts 02766 508 946 5100 Fax 508 946 9500 E mail info mccdag com www mccdag com
26. tails on the actual thermocouple error Note 4 Thermocouples must be connected to the device such that they are floating with respect to GND The GND pins are isolated from earth ground so connecting thermocouple sensors to voltages referenced to earth ground is permissible as long as the isolation between the GND pins and earth ground is maintained Note 5 When thermocouples are attached to conductive surfaces the voltage differential between multiple thermocouples must remain within 1 4V For best results we recommend the use of ungrounded or insulated thermocouples when possible Throughput rate Table 4 Throughput rate specifications Number of input channels Maximum throughput 2 S s 2 S s on each channel 4 S s total 2 S s on each channel 6 S s total 2 S s on each channel 8 S s total 2 S s on each channel 10 S s total 2 S s on each channel 12 S s total 2 S s on each channel 14 S s total CLAD NPR WL N Re 2 S s on each channel 16 S s total 16 USB TC User s Guide Specifications Note 6 The analog inputs are configured to run continuously Each channel is sampled twice per second The maximum latency between when a sample is acquired and the temperature data is provided by the USB unit is approximately 0 5 seconds Digital input output Table 5 Digital input output specifications Parameter Specification Digital type CMOS Number
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