Home

SC-207X Series User Manual

1. o Lo 28d O Fo o Lo o4 vad O J8 o Fo 98d O FO o FoG 00d J o eod o Fo FO FO J6 FO o vod O o 99d O Fo Fo FOG J5 o SIBNLIX3O0 o E4 C1 KT o Lo NNOI1X3 O Fo Fo J4 o 083109 O o NATIONAL ASSY180955 01 REU B S N NSTRUMENTS SC 2071 COPYRIGHT 1991 FO FO Fo o 183199 o eo OO 218 G18 O O o 0 O00 J3 eaino emo eo o oo ooo0ooo oojooooodo9 eo ojo eje ee ejo eje ee eje eje eee yN loo F1 JOO ox fal ENT o EH General Purpose Breadboard Area Fuse Shield Ground Selection 5 6 7 Daisy Chaining 50 pin I O Connector 50 pin I O Connector Temperature Sensor Selection Temperature Sensor 1 2 3 4 Figure 3 1 SC 2071 Board Parts Locator Diagram Analog Input Each differential analog input has four open positions for signal conditioning components AII signal conditioning components are designated as resistors but capacitors can be inserted for the construction of RC filters The board is shipped with wire jumpers in one position for each input The equivalent circuit of one input is shown in Figure 3 2 For specific application
2. anaonnags User Manual 4 4 National Instruments Corporation Chapter 4 SC 2072 Board Warning If the DAQ device does not use pins 33 34 or pins 49 50 for power connections or if the external power supply is used set switch S2 to position B Failure to set switch S2 to position B under these conditions could result in damage to your external power supply the SC 2072 and its breadboarded circuitry the expansion board connected to the SC 2072 and or your computer National Instruments is NOT liable for damage resulting from such connections The base model of the SC 2072 the SC 2072 comes with an additional three position screw terminal block that can be used to supply positive negative and common analog ground voltage signals to the board If you have this version of the board and want to install filter capacitors for the supplies you can install them in positions C1 and C2 next to J4 If you choose to install capacitors in these holes the capacitors should be high quality tantalum capacitors that are rated at least several volts over your power supply outputs For example if you connect 12 V to the board you need capacitors rated for 16 V the next rating above 12 V Install the positive terminal of the capacitor in the hole adjacent to the plus symbol The second model of the SC 2072 the SC 2072D comes with a DCto DC converter and accompanying filter capacitors On this version of the board no screw termi
3. zx m a a 000000000000000 V o 000000000000007 Z 00000000000000000000000 00000000000000000000000 00000000000000000000000 00000000000000000000000 00000000000000000000000 000000000000000000000000 o o o o o 000000000000 0000000000000 o oo oo oo oo oo oo oo oo oo oo o o o o o o o o o o o o o o o o 0000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 00000000000000000000000000000000 0000000000000000000000000000000 0000000000000000000000000 0000000000000000000000000 0000000000000000000000000 0000000000000000000000000 c POWER SELECTOR 000000000000000000 0000000000000000 00000000000000 0000000000000 o o o o o o o o o o o o o o o o o o o o o o 000 0000000000000 00000000000000 U 5U o 000000000000000 000000000000000 000000000000000 000000000000000 ED GND coN DGND o OOOOOOOOOOOH 000000000000 o 0000000 0000000 0000000 0000000 I EXTERNA POWER INPUTS 9 General Purpose Screw Block Terminals Connector J5 Switch S2 Screw Block Terminals for Analog Power Connector J4 External Power Screw Block Terminals Connector J3 Screw Block Terminals for 1 0 Connector Signals Connector J3 Switch S1 50 pin I O Connector General Purpose Brea
4. National Instruments Corporation 1 5 SC 207X Series User Manual Chapter 2 SC 2070 Board This chapter describes the SC 2070 board in detail including function compatibility connection mounting and applications This chapter also discusses working with thermocouples The SC 2070 is a general purpose termination breadboard that makes it easy to connect to all MIO 16 board I O signals add analog input signal conditioning such as filters dividers and thermocouple compensation and build external custom timing analog and digital circuits The SC 2070 board is used with National Instruments DAQ boards for the Macintosh NB Series IBM PS 2 Micro Channel MC Series and PC XT AT and compatible AT Series computers The SC 2070 board has screw terminals for all DAQ board signals With these terminals the board easily connects to the analog digital timing and trigger signals The SC 2070 has an onboard temperature sensor that can be optionally jumpered to differential channel 0 for thermocouple cold junction compensation With open component positions in the input paths you can insert resistors and capacitors for conditioning the 16 single ended or 8 differential analog input signals A 1 5 by 4 in general purpose breadboard area is also included The SC 207X Series boards can also be used in conjunction with the other signal conditioning accessories including the SC 206X Series boards and SSR Series boards To connect multiple
5. 3 5 Daisy chaining a Lab 1200 Device to a BNC 2081 sess 3 6 Connection between a Lab 1200 Device and the SC 2071 Board via the 56 2033 BOGEL uim iet edito e she AN endo esiste a ree Maec 3 6 Normalized Frequency Response of Lowpass Filter sess 3 9 Low pass Filter on Channel lis ee eese ie men 3 10 Normalized Frequency Response of Highpass Filter 3 11 Hishpass Filter on Channel aus iie tee oritur ER NEIN RO HOUR Car MR IURE 3 12 Attenuator for Use with SC 2071 Board Inputs eee 3 13 Thermocouple Circuit with Open Thermocouple Detect and Lowpass or gulis 3 16 SC 2072 Board Parts Locator Diagram 4 2 SC 2072D Board Parts Locator Diagram eese 4 3 Direct Connection between a TIO 10 Board and the SC 2072 Board 4 6 Connection between a DIO 24 Board and the SC 2072 Board via the SC 205 1 Bo atd oes ennan na p a EE XR ERA Deed oU QUU edes 4 6 Mounting Locations for SC 207X Series Boards sss 5 3 Attaching a Mountable Board to the Chassis 5 3 Double Height Mounting ni tertie eh ot tn tae stad cose ree te Ren kon Hiero nus 5 4 Connections Between DAQ Devices and SC 205X Series Boards and Between SC 205X Series Boards and SC 2070 and 86 207 T1 Boards eiecti eite et sci ie eet tecta v t nee are 5 7 National Instruments Corporation
6. National Instruments Corporation 2 23 SC 207X Series User Manual SC 2070 Board Chapter 2 Table 2 5 Thermocouple Measurement Accuracies Additional Signal Connection Information For more information about signal connections see Chapter 2 in your MIO 16 board user manual SC 207X Series User Manual 2 24 National Instruments Corporation Chapter 3 SC 2071 Board This chapter describes the SC 2071 board in detail including function compatibility connection mounting and applications This chapter also discusses working with thermocouples The SC 2071 is a general purpose termination breadboard that makes it easy to connect to all Lab 1200 device I O signals add analog input signal conditioning such as filters dividers and thermocouple compensation and build external custom timing analog and digital circuits The SC 2071 board is used with the National Instruments Lab 1200 devices for the Macintosh IBM PC XT AT and compatible computers The SC 2071 board has screw terminals for eight single ended input channels Open component positions at each analog input facilitate the addition of user selected signal conditioning The SC 2071 board has an onboard temperature sensor that can be optionally jumpered to channel 0 for thermocouple cold junction compensation With open component positions in the input paths you can insert user supplied resistors and capacitors for conditioning the eight single ended analog input sign
7. connector J2 is tied directly to the correspondingly numbered terminal on screw terminal block J3 External I O lines can be tied directly to the I O cable by connecting the lines to screw terminal block J3 In addition a 12 position screw terminal block J5 can be used to connect external signals to the breadboard area without connecting them to the I O cable simultaneously A line of solder holes adjacent to both J3 and J5 can be used to connect the screw terminals to the breadboard area If you rotate the SC 2072 board so that the label J3 is in the top left corner the connection holes are to the right of J3 The even numbers to the right of J3 correspond to the screw terminals themselves not to the connection holes However these numbers can be used to determine the line number The holes just slightly up from the numbers correspond to that numbered signal be careful here as the holes are numbered 2 1 4 3 6 5 50 49 If you rotate the SC 2072 board so that the label J5 is closest to the top left corner the connection holes are to the right of J5 In this case the hole directly to the right of a terminal is connected to that terminal For more information on the signals present on the I O cable connector consult your expansion or other signal conditioning board manual National Instruments Corporation 4 3 SC 207X Series User Manual SC 2072 Board Power Connections Chapter 4 Because the SC 2072 board is a general pur
8. inaccuracy of the temperature sensor and temperature differences between the sensor and the screw terminals The sensor used on the SC 2071 board is specified to be accurate to 1 C Minimize temperature differences between the sensor and the screw terminals by keeping the SC 2071 board away from drafts heaters and warm equipment Linearization error is a consequence of the fact that the polynomials are by their very nature approximations of the true thermocouple output The linearization error is dependent on the degree of polynomial used Table 3 4 lists the linearization errors for the NBS polynomials Measurement error is the result of inaccuracies in the Lab 1200 device These inaccuracies include gain and offset If the device is properly calibrated the offset error should be zeroed out The only remaining error is a gain error of 0 08 of full range see the Lab 1200 device specifications If the input range is 5 V and the gain is 100 then the gain error contributes 0 0008 x 100 mV or 80 LV of error If the Seebeck coefficient of a thermocouple is 32 uV C this measurement error adds 2 5 C of uncertainty to the measurement For best results use a well calibrated Lab 1200 device so that offsets can be neglected Offset error can be eliminated however by grounding one channel on the SC 2071 board and measuring it This value is the offset of the Lab 1200 device and it can then be subtracted in software from all other readings Fin
9. 15 Input Filtering and Broken Thermocouple Detection Optional 3 15 Selecting the Gain and Input Range sene tures ee eaten eee 3 16 Isnedrtzme the Datac ss Gode eei pe tpi e MR dal ME DS 3 17 Measurement ConmnectlOns 5eme initie 3 18 An Example of Using Thermocouples eene 3 19 SOURCES OL EM OL d tels 3 19 Thermocouple Measurement Accuracies 3 20 Additional Signal Connection Information ss 3 2 Chapter 4 5C 2072 Board iii or tiet RI PER but nq ee ane ae 4 1 Signal C Onfti ctlons or oinin a a ees tut E A E S 4 3 Power C nnectonS es Gesi rsa Si E aE EE E E E N 4 4 Fuses and Power LED ikiii i i i vg Bt a medi ae ad a es A ae 4 5 Board fo Board Cable Rss ss SR ausu i RENE eR 4 6 Montin onea an e a SE ARR ENS E A E RE 4 7 Soldering and Desoldering on the SC 2072 Board 4 7 SC 207X Series User Manual vi National Instruments Corporation Contents Chapter 5 Installation and Connections eerte 5 1 Hardware Installatiob 5 ciue martine ee A ne dent teu 5 1 Hardware Installation for the SC 2070 and the SC 2071 sess 5 1 Hardware Installation for the SC 2072 eee nnne 5 2 Installing the SC 205X Series Cable Adapter Boards sss 5 2 Installing the BNC 2081 Analog Breakout Board 5 3 hend dvi 5 3 Ex
10. 25 V the SC 2071 board is at 25 C 2 Read the voltage on analog input channel 1 using a gain of 100 If you are using an NI DAQ software package you can usethe AT Read and AI Scale functions to read the channel 3 Translate the voltage reading into an uncompensated temperature using either a look up Table or a polynomial such as that described in Formula 3 4 For example assume that the reading from the thermocouple is 9 39 mV By applying Formula 3 6 and the coefficients from Table 3 4 you can calculate that the uncompensated temperature is 175 C 4 Add the cold junction temperature from step 1 to the uncompensated temperature obtained in step 3 This result is the temperature at the measuring end of the thermocouple For the example given the temperature is 175 C 25 C 200 C The method of temperature calculation used in this example yields only an approximate value For a discussion on the preferred method of temperature calculation which uses voltage compensation calculations see National Instruments Application Note 043 Measuring Temperature with Thermocouples Sources of Error When making thermocouple measurements with the SC 2071 board and a Lab 1200 device the possible sources of error are compensation linearization measurement and thermocouple wire errors National Instruments Corporation 3 19 SC 207X Series User Manual SC 2071 Board Chapter 3 Compensation error can arise from two sources
11. 8 single ended inputs 2 9 nonreferenced or floating signal sources 2 7 to 2 8 differential inputs 2 7 to 2 8 single ended inputs 2 8 SC 207X Series User Manual signals digital and timing SC 2070 board 2 4 to 2 5 SC 2071 board 3 5 single ended inputs ground referenced signal sources 2 9 nonreferenced or floating signal sources 2 8 single ended thermocouple measurements SC 2070 board 2 23 example 2 23 to 2 24 soldering and desoldering SC 2070 board 2 7 SC 2071 board 3 7 SC 2072 board 4 7 specifications analog input A 1 breadboarding area A 1 environment A 2 physical A 2 power requirements from DAQ device A 1 switches See jumpers and switches T technical support B 1 temperature sensor cold junction temperature sensor specifications A 1 SC 2070 board 2 3 to 2 4 W1 jumper settings figure 2 4 SC 2071 board 3 4 W1 jumper settings figure 3 4 Thermocouple Law of Intermediate Metals 2 17 3 14 thermocouple measurements SC 2070 board See SC 2070 board SC 2071 board See SC 2071 board thermocouple output voltages linearizing SC 2070 board 2 20 to 2 21 SC 2071 board 3 17 to 3 18 National Bureau of Standards NBS polynomial coefficients table 2 21 3 18 thermocouples definition 2 17 3 14 National Instruments Corporation purpose and use 2 17 3 14 timing signals SC 2070 board 2 4 to 2 5 SC 2071 board 3 5 U unpacking SC 207X Series boards 1 5 V voltage dividers
12. 9 SC 2071 board 3 8 H hardware installation See installation highpass filters building SC 2070 board 2 13 to 2 14 highpass filter on differential channel 1 figure 2 14 normalized frequency response figure 2 13 poor common mode rejection characteristics note 2 14 SC 2071 board 3 10 to 3 12 highpass filter on channel 1 figure 3 12 normalized frequency response figure 3 11 I input ranges See gain and input ranges installation BNC 2081 Analog Breakout Board 5 3 external power connection 5 4 to 5 5 amount of power supplied by DAQ devices table 5 6 mounting rack mounting 5 3 to 5 4 attaching mountable board to chassis figure 5 3 double height mounting figure 5 4 locations for SC 207X boards figure 5 3 SC 2070 board 2 6 SC 2071 board 3 7 SC 2072 board 4 7 Index 2 National Instruments Corporation SC 205X Series cable adapter boards 5 2 SC 207X Series board connection 5 7 SC 2070 and SC 2071 boards 5 1 to 5 2 SC 2072 board 5 2 signal connections 5 8 to 5 9 rack mount chassis cover attachment 5 9 ribbon cable connectors 5 8 SC 205X Series board connectors compatible with SC 207X boards table 5 8 screw terminal connections SC 2070 and SC 2071 5 8 SC 2072 5 9 J jumpers and switches SC 2072 board setting switch S2 to position B warning 4 4 switch S2 settings for National Instruments DAQ devices table 4 4 W1 jumper SC 2070 temperature sen
13. ERREUR diei 5 mA typ with no user circuitry connected Note The power specifications pertain to the power supply of the host computer when using internal power or to the external supply connected at the 5 V screw terminal when using external power The maximum power consumption of the SC 2070 board is a function of the signal conditioning components installed and any circuits constructed on the general purpose breadboard area If the board is being powered from the host computer the maximum 5 V current draw is fuse limited to 800 mA National Instruments Corporation A 1 SC 207X Series User Manual Specifications Appendix A Physical Dimensions including standoffs sss 20 1 by 12 5 by 4 6 cm 7 9 by 4 9 by 1 8 in Signal connections essere 54 screw terminals VO connector eee rer entere One 50 pin male ribbon cable connector Environment Operating temperature 0 to 70 C Storage temperature esee rennen menn 55 to 110 C Relative humidity ss 5 to 90 noncondensing SC 207X Series User Manual A 2 National Instruments Corporation Appendix B Customer Communication For your convenience this appendix contains forms to help you gather the information necessary to help us solve technical problems you might have as well as a form you can use to comment on the product documentation Filling out a copy of the Technical Support Form before contacting National Instrum
14. Lowpass Filters Building Highpass Filters and Building Attenuators later in this chapter can be used Building Lowpass Filters You can easily install simple RC lowpass filters in the SC 2071 board on any input channel The filters are useful for accurate measurement and noise rejection By substituting resistance and capacitance values into the following formula you can calculate a simple one pole RC filter to have a 3 dB point cutoff frequency 1 f OxRC Formula 3 1 The frequency response rolls off at a rate of 20 dB per decade of increase thereafter A Bode plot of the amplitude versus normalized frequency is shown in Figure 3 8 SC 207X Series User Manual 3 8 National Instruments Corporation Chapter 3 SC 2071 Board Amplitude 1 0 1 0 01 100 1 000 10 000 Normalized Frequency Figure 3 8 Normalized Frequency Response of Lowpass Filter When measuring low frequency signals about 4 Hz if you have 400 Hz noise on your inputs you can add a lowpass filter with a cutoff frequency of 4 Hz The 400 Hz noise then attenuates by 40 dB Notice that your 4 Hz signal also attenuates but by only 3 dB Do not neglect any potential attenuation of signals of interest by this low order filter You must also choose the filter component values The resistance or the capacitance can be selected arbitrarily one value determines the other Picking the capacitor first and letting its value determine the resi
15. Resistor Input Schematic Re 10kQ Channel 7 O ANN O Channel 92 Figure 2 12 Attenuator for Use with Differential Inputs Example Using the values in Figure 2 12 10 KQ 1 ere 0kQ 10kQ 10kQ 3 Therefore 1 VMIO7 3 Vsc When the MIO 16 is configured for 10 V inputs the board can acquire 30 V signals with this attenuator circuit National Instruments Corporation 2 15 SC 207X Series User Manual SC 2070 Board Chapter 2 Working with Thermocouples One of the most frequently used temperature transducers is the thermocouple A thermocouple is created when two dissimilar metals are brought in contact and the contact produces a small voltage as a function of temperature In most measurement situations a thermocouple is placed where the temperature is to be measured then two wires consisting of the same type of metal as each side of the thermocouple are run back to a termination panel such as the SC 2070 Additional dissimilar junctions are formed where these wires contact the screw terminals and each of these junctions generates its own temperature dependent voltage Other temperature dependent voltages are generated at ribbon cable junctions and solder joints However effects of these junctions are negligible and tend to cancel in most cases The voltage measured by the DAQ board is the sum of the voltages of all dissimilar metal junctions in the circuit not just the thermocouple junction us
16. See attenuators building National Instruments Corporation Index 7 Index SC 207X Series User Manual
17. a high pressure boiler system using a PC AT computer an AT MIO 16L board in differential mode an SC 2070 board and a J type thermocouple The maximum temperature that can be reached in this example is 300 C Before taking readings you must configure the AT MIO 16L board for the maximum resolution possible A thermocouple table shows that the output voltage never exceeds 16 mV to 17 mV recall that the exact voltage measured is a function of the SC 2070 temperature as well as the temperature being measured Therefore either a 5 V input range with a gain of 100 50 mV maximum signal or a 10 V input range with a gain of 500 20 mV maximum signal can be selected In this case the 10 V input range with a gain of 500 gives the best resolution Set the jumpers on the AT MIO 16L for differential input 10 V input range Jumper W1 on the SC 2070 board is set to select the temperature sensor as shown in Figure 2 3 To connect the thermocouple to differential channel 1 connect one lead to the CHI terminal and the other to the CH9 terminal Notice that no thermocouples can be read on channel 0 A bias return resistor in the range of 10 kQ to 100 kQ is soldered to R10 for the bias current return path For this example you do not add any lowpass filters or broken thermocouple detection The procedure for this example is as follows 1 Read the voltage from the temperature sensor channel 0 If you are using an NI DAQ software package you can use th
18. acrylic plastic cover single or double height Rack mount chassis kit with metal wraparound cover single or double height SSR Series eight channel backplane with 0 4 m cable for SC 2050 Series SC 2060 and 26 conductor cable 0 2 or 0 4 m SC 2061 and 26 conductor cable 0 2 or 0 4 m SC 2062 and 26 conductor cable 0 2 or 0 4 m SC 2050 and 50 conductor cable 0 5 or 1 0 m SC 2051 and 50 conductor cable 0 5 or 1 0 m SC 2052 and 50 conductor cable 0 5 or 1 0 m SC 2053 and 50 conductor cable 0 5 or 1 0 m PR50 50F cable Software The SC 207X Series boards require no additional software support beyond what you are using for your DAQ device SC 207X Series User Manual 1 4 National Instruments Corporation Chapter 1 Introduction Unpacking Your SC 207X board is shipped in an antistatic package to prevent electrostatic damage to the board Electrostatic discharge can damage several components on the board To avoid such damage in handling the board take the following precautions Ground yourself via a grounding strap or by holding a grounded object Touch the antistatic package to a metal part of your computer chassis before removing the board from the package Remove the board from the package and inspect the board for loose components or any other sign of damage Notify National Instruments if the board appears damaged in any way Do not install a damaged board into your computer Never touch the exposed pins of connectors
19. and Timing Signals All of the signals from the MIO 16 board are made available at screw terminals on the SC 2070 board Because these signals are not conditioned or changed in any way by the SC 2070 board refer to your MIO 16 board user manual for information on using these signals If you want optical isolation of or relay control by the digital I O lines then you must use the SC 2050 cable adapter board and the appropriate SC 2060 digital signal conditioning board For more information on the SC 205X Series boards or the SC 206X Series boards refer either to your National Instruments catalog the SC 205X Series User Manual or the SC 206X Series User Manual SC 207X Series User Manual 2 4 National Instruments Corporation Chapter 2 SC 2070 Board Board to Board Cabling The SC 2070 board connects directly to any of the DAQ boards listed in Table 2 2 Table 2 2 DAQ Boards Used with the SC 2070 Board NB Series MC Series AT Series Macintosh IBM PS 2 PC AT SC 2070 NB MIO 16 MC MIO 16 AT MIO 16 NB MIO 16X AT MIO 16D AT MIO 16F 5 AT MIO 16X AT MIO 64F 5 Requires an NBS cable available separately The DAQ boards listed in Table 2 2 connect to the SC 2070 board as shown in Figure 2 5 If you are using the SC 2070 board with the AT MIO 16D or AFMIO 64E5 board the 50 conductor cable is replaced with a type NB5 100 conductor ribbon cable The NB5 cable terminates with two 50 pin connectors one of which may be connecte
20. any damages or injuries resulting from incorrect signal connections SC 207X Series User Manual 5 8 National Instruments Corporation Chapter 5 Installation and Connections Screw Terminal Connections for the SC 2072 The SC 2072 board connects all fifty I O signals from the DAQ device to screw terminals on board Additionally twelve undedicated screw terminals are located adjacent to the general purpose breadboarding area Warning Connections including power signals to ground and vice versa that exceed any of the maximum input or output voltage ratings on the SC 207X Series boards can result in damage to any or all of the boards connected to the SC 207X Series boards to the host computer and to the SC 207X Series boards Overvoltage conditions also can present a shock hazard to you National Instruments is NOT liable for any damages or injuries resulting from incorrect signal connections Rack Mount Chassis Cover Attachment The optional 19 in rack mount accessory includes a flat acrylic plastic cover that can be installed using the four screws included in the kit Covering the top and bottom is required for safety reasons if an SC 206X Series board in the same enclosure is to be used in high voltage situations see the following warning Remember that voltages above the 42 V peak cannot be applied to the SC 207X Series inputs Warning The SC 206X Series boards must be completely enclosed if any onboard voltages or any voltages
21. connect the positive thermocouple lead to channel 1 and the negative thermocouple lead to AIGND For this example you do not add any lowpass filters or broken thermocouple detection The procedure for this example is as follows 1 Read the voltage from the temperature sensor If you are using an NI DAQ software package you can use the AT Read and AI Scale functions to do the reading The temperature sensor voltage is the voltage on channel 0 This voltage is 10 mV C so the gain should be either 1 or 10 10 for the best resolution Multiply the voltage by 100 to get the SC 2070 temperature in degrees Celsius For example if the reading is 0 25 V then the SC 2070 is at 25 C 2 Read the voltage on analog input channel 1 using a gain of 500 If you are using an NI DAQ software package you can use the AT Read and AT Scale functions to read the channel 3 Translate the reading into an uncompensated temperature using either a look up table or a polynomial such as that described in Formula 2 4 For example assume that the reading from the thermocouple is 9 39 mV By applying Formula 2 6 and the coefficients from Table 2 4 you can calculate that the uncompensated temperature is 175 C 4 Add the cold junction temperature from step 1 to the uncompensated temperature obtained in step 3 This result is the temperature at the measuring end of the thermocouple For the example given the temperature of the boiler system is 175 C
22. connections between DAQ devices and SC 205X Series boards figure 5 7 power requirement specifications A 1 supported by SC 207X Series boards table 1 2 differential DIFF input mode 2 7 differential inputs ground referenced signal sources 2 9 SC 207X Series User Manual Index nonreferenced or floating signal sources 2 7 to 2 8 bias return resistor for DC coupled floating source on channel 1 figure 2 8 differential thermocouple measurements SC 2070 board 2 22 example 2 22 to 2 23 digital and timing signals SC 2070 board 2 4 to 2 5 SC 2071 board 3 5 documentation conventions used in manual xii organization of manual xi related documentation xii xiii E environment specifications A 2 equipment optional 1 4 error sources for thermocouple measurements SC 2070 board 2 24 SC 2071 board 3 19 to 3 20 F fax technical support B 1 floating signal sources See also nonreferenced or floating signal sources connecting SC 2071 board 3 8 fuses SC 2070 board 2 4 SC 2071 board 3 4 SC 2072 board 4 5 G gain and input ranges thermocouple measurement SC 2070 board 2 19 SC 2071 board 3 16 thermocouple voltage output extremes SC 2070 board table 2 20 SC 2071 board table 3 17 SC 207X Series User Manual getting started with SC 207X Series boards 1 4 ground referenced signal sources channel configuration 2 7 connecting SC 2070 board 2 9 differential inputs 2 9 single ended inputs 2
23. for a 20 kHz highpass filter placed on input channel 1 National Instruments Corporation 3 11 SC 207X Series User Manual SC 2071 Board Chapter 3 Component Positions R8 8 2kQ nono R7 h l1 Channe R6 a 0 001 uF cap R5 HE 8 2 kQ Resistor 0 001 uF Capacitor Input Schematic 0 001 uF Channel O O C gt AIGND Figure 3 11 Highpass Filter on Channel 1 Building Attenuators Voltage Dividers You can connect attenuators voltage dividers to the analog inputs of the SC 2071 board Attenuators can be used to reduce a signal that is outside the normal input range of the DAQ device 10 V maximum Warning The SC 2071 board is not designed for any input voltages greater than 42 V even if a user installed voltage divider reduces the voltage to within the input range of the DAQ device Input voltages greater than 42 V can result in damage to the SC 2071 board any and all devices connected to it and the host computer Overvoltage can also cause an electric shock hazard for the operator National Instruments is NOT liable for damage or injury resulting from such misuse SC 207X Series User Manual 3 12 National Instruments Corporation Chapter 3 SC 2071 Board A two resistor circuit for attenuating voltages at the single ended inputs of the SC 2071 board is shown in Figure 3 12 The Figure also shows the placement of the resistors on the open component posi
24. in this case Note Highpass filters generally exhibit poorer common mode rejection characteristics than lowpass filters because capacitors are in the series input paths Capacitors have poorer tolerances than resistors and matching of the input impedances is crucial for good common mode rejection The SC 2070 board open component locations do not facilitate RC highpass filters with the MIO 16 board configured for single ended inputs Therefore if the MIO 16 board is configured for single ended inputs highpass filters must be built on the custom breadboard area Component Positions R12 0 001 uF Channel 9 in Channel 1 4 in R8 RQ 0 001 uF R7 7 6 34 kO Resistor B 0 001 uF Capacitor Input Schematic 0 001 uF Channel VY O E To G Input 6 34 kQ Multiplexer O F Channel C2 C C 0 001 uF Figure 2 11 Highpass Filter on Differential Channel 1 National Instruments Corporation 2 13 SC 207X Series User Manual SC 2070 Board Chapter 2 Building Attenuators Voltage Dividers Attenuators voltage dividers can be connected to the analog inputs of the SC 2070 board when the inputs from its DAQ board are in differential mode The SC 2070 board open component positions do not facilitate voltage dividers with the MIO 16 board configured for single ended inputs Therefore if the MIO 16 board is configured for single ended inpu
25. kQ 4 19 8 kQ Resistor 7 1 uF Capacitor Input Schematic 19 8 kQ Channel Y OA E To Input Multiplexer Channel 7 Figure 2 9 Lowpass Filter on Differential Channel 1 National Instruments Corporation 2 11 SC 207X Series User Manual SC 2070 Board Chapter 2 Building Highpass Filters Simple RC highpass filters are easily installed in the SC 2070 board on any differential input channel The filters are useful for accurate high frequency measurement and low frequency noise rejection By substituting resistance and capacitance values into the following formula you can calculate a simple one pole RC filter to have a 3 dB point cutoff frequency 1 c RO Formula 2 2 The frequency response rolls off at a rate of 20 dB per decade decrease thereafter A Bode plot of the amplitude versus normalized frequency is shown in Figure 2 10 Amplitude 1 0 1 0 01 0 0001 0 01 Normalized Frequency Figure 2 10 Normalized Frequency Response of Highpass Filter When measuring high frequency signals about 50 kHz if you have 50 Hz noise on your inputs you can add a highpass filter with a cutoff frequency of 50 kHz The 50 Hz noise then attenuates by 60 dB Notice that your 50 kHz signal also attenuates but by only 3 dB Do not neglect any potential attenuation of signals of interest if you add a low order filter You must also choose the filter component
26. memory usage The polynomials are in the form T ao tax aox 3x Formula 3 4 where x is the thermocouple voltage in volts T is the temperature difference between the measuring end and the SC 2071 board screw terminals in degrees Celsius and ag through a are coefficients that are specific to each thermocouple type To speed computation time a polynomial should be computed in nested form Consider the fourth order polynomial T ao ajx a2x2 ay a4x Formula 3 5 If this polynomial is evaluated as it is written then several unnecessary multiplications are performed to raise x to the various powers On the other hand if the polynomial is written and evaluated as follows no powers are computed and execution proceeds much faster T ao x a x a2 x a3 xa4 Formula 3 6 Table 3 4 lists the NBS polynomial coefficients for several popular thermocouples National Instruments Corporation 3 17 SC 207X Series User Manual SC 2071 Board Chapter 3 Table 3 4 NBS Polynomial Coefficients 100 to 1 000 C 0 to 760 C 0 to 1 370 C 0 to 1 000 C 0 to 1 7509 C 160 to 400 C 0 5 C 0 1 C 0 7 C 0 5 C 1 c 0 5 C 1 10866E 10 2018441314 4 83506E 10 7 62091E 14 1 88027E 14 6 97688E 11 1 The accuracies shown apply only to the polynomial and do not take into consideration errors introduced by the SC 2071 board the Lab 1200 device or the thermocouple itself These polynomi
27. selecting gain and input ranges 3 16 to 3 17 thermocouple voltage output extremes figure 3 17 sources of error 3 19 to 3 20 working with thermocouples 3 14 SC 2072 board board to board cabling 4 6 connecting to incompatible board warning 4 6 connection via SC 2072 board figure 4 6 direct connection to TIO 10 board figure 4 6 SC 207X Series User Manual Index DAQ devices supported table 1 2 features 4 1 fuses and power LED 4 5 installation 5 2 mounting 4 7 overview 4 1 parts locator diagram 4 2 power connections 4 4 to 4 5 accidental shorting of terminals at J4 warning 4 5 setting switch S2 to position B warning 4 4 switch S2 settings for National Instruments DAQ devices table 4 4 screw terminal connections 5 9 signal connections 4 3 soldering and desoldering on 4 7 SC 2072D board See also SC 2072 board parts locator diagram 4 3 screw terminal connections SC 2070 and SC 2071 5 8 SC 2072 5 9 Seebeck coefficient 2 20 3 17 shield ground SC 2070 board 2 4 SC 2071 board 3 4 signal connections 5 8 to 5 9 rack mount chassis cover attachment 5 9 ribbon cable connectors 5 8 SC 205X Series board connectors compatible with SC 207X boards table 5 8 SC 2072 board 4 3 screw terminal connections SC 2070 and SC 2071 5 8 SC 2072 5 9 signal source connections floating signal sources SC 2071 board ground referenced signal sources 2 9 differential inputs 2 9 SC 2071 board 3
28. then be approximated by a much lower order polynomial such as the polynomial in Formula 2 6 Further examples of polynomials including lower order polynomials for subdivided temperature ranges can be found in NIST Monograph 175 Temperature Electromotive Force Reference Functions and Tables for the Letter Designated Thermocouple Types Based on the ITS 90 National Institute of Standards Technology Gaithersburg MD 20899 SC 207X Series User Manual 2 20 National Instruments Corporation Chapter 2 SC 2070 Board Differential Measurements Connect the temperature sensor to channel 0 and channel 8 differential channel 0 by configuring jumper W1 as shown in Figure 2 3 Connect the thermocouples to the appropriate pairs of input channel screw terminals for example CH1 and CH9 CH2 and CH10 and so on Notice that some thermocouples such as those from Omega Engineering Stamford CT have red insulation on the negative terminal Check with the vendor to determine the output polarity of any particular thermocouple Because thermocouples are floating signal sources a bias return resistor in the range of 10 to 100 kQ must be attached between the channel and GND which is connected to the MIO 16 AIGND analog input ground For more information about signal sources and their connections see Chapter 2 in your MIO 16 board user manual An Example of Using Thermocouples in Differential Mode Assume that you are measuring the temperature of
29. to 30 W when soldering to the board To desolder on the SC 2070 vacuum type tools work best Use care when desoldering to avoid damaging component pads Only use rosin core electronic grade solder Acid core solder damages the printed circuit board and components SC 207X Series User Manual 2 6 National Instruments Corporation Chapter 2 SC 2070 Board Channel Configurations You can configure the analog input channels of an MIO 16 board for one of three input modes differential DIFF input referenced single ended input RSE or nonreferenced single ended NRSE input As described in Chapter 2 of the MIO 16 user manual the input configuration of the MIO 16 depends on the type of signal source There are two types of signal sources nonreferenced or floating signals and ground referenced signals To measure floating signal sources configure the MIO 16 for referenced single ended input or differential input with bias resistors To measure ground referenced signal sources configure the MIO 16 for nonreferenced single ended input or differential input Both types of signal sources and the recommended methods for MIO 16 board connection are discussed as follows Connecting Nonreferenced or Floating Signal Sources A floating signal source is a signal source that is not connected in any way to the building ground system but has an isolated ground reference point If an instrument or device has an isolated output that instrument or devi
30. values The resistance or the capacitance can be selected arbitrarily one value determines the other Picking the capacitor first and letting its value determine the resistance required is preferable because more standard resistor values are available The filter circuit has one series capacitor on each input of the differential channel Because the two capacitors are in series the capacitance value that must be substituted into Formula 2 2 is the series capacitance of the two capacitors in series For two capacitors in series the net capacitance is the reciprocal of the sum of the reciprocals of the two capacitances For example two 0 001 uF capacitors in series have a net capacitance of 0 0005 uF The two capacitors should be the same value or the common mode rejection is degraded If capacitors of 0 001 uF are available the resistance is by substitution into Formula 2 2 6 366 Q or about 6 4 kQ Therefore in this example the input channel has a 6 37 kQ resistor or closest standard value in its capacitor position G The closest standard 596 tolerance SC 207X Series User Manual 2 12 National Instruments Corporation Chapter 2 SC 2070 Board resistors are 6 2 KQ The closest standard 1 resistors are 6 34 KQ Figure 2 11 shows both the schematic and the component placement for a 50 kHz highpass filter placed on differential input channel 1 If the input signal source is floating a bias return resistor must be placed in the D position RIO
31. 0000 00000 0000000000 00000 000000000000000 000000000000000 000000000000000 2000000000 00000 O00000000000000 000000000000000 000000000000000 000000000000000 000000000 00000 9 EXTSTROBE o EXTGATE o O000000000000000000000P08 o o SRC1 o o o 5U o o BDIO2 o o o BDIOO o o DGND o ADGND o EXTREF O000000000000000000000P00 ol e DAC1OUT o O uO c No C oO Ee C OO000000000000000000000000000000000000000 OO000000000000000000000000000000000000000 O O O O O ADGND O O O ei p EXT REF DACO OUT GATE1 O EXT CONU EXT TRIG SCAN CLK 5U 0104 O ania O api01 O apro O 1 50 pin I O Connector 4 General Purpose Breadboard Area 2 Temperature Sensor Selection 5 Fuse 3 Temperature Sensor 6 Shield Ground Selection Figure 2 1 SC 2070 Board Parts Locator Diagram Analog Input Each differential analog input has seven open positions for signal conditioning components Six of these positions are designated as resistors and one is designated as a capacitor The board is shipped with jumpers in two positions for each input The equivalent circuit of one input is shown in Figure 2 2 The board can be used when the MIO 16 board is configured for both 16 sin
32. 100 kQ Resistor Input Schematic Channel A O To Input Multiplexer Channel 9 Figure 2 7 Bias Return Resistor for DC Coupled Floating Source on Channel 1 Single Ended Inputs When measuring floating signal sources configure the MIO 16 board to supply a ground reference Therefore configure the MIO 16 for referenced single ended input In this configuration the negative input of the MIO 16 instrumentation amplifier is tied to the analog ground Therefore use the SC 2070 board in its factory configuration In the factory configuration jumpers are in the two series positions E and F see Table 2 1 In this configuration all of the signal grounds should be tied to AIGND Signal conditioning circuitry such as filters and attenuators described in Building Lowpass Filters Building Highpass Filters and Building Attenuators later in this chapter can be built in the open component positions SC 207X Series User Manual 2 8 National Instruments Corporation Chapter 2 SC 2070 Board Connecting Ground Referenced Signal Sources A grounded signal source is connected in some way to the building system ground therefore the signal source is already connected to a common ground point with respect to the DAQ board assuming the host computer is plugged into the same power system Nonisolated outputs of instruments and devices that plug into the building power system fall i
33. 25 C z 200 C SC 207X Series User Manual 2 22 National Instruments Corporation Chapter 2 SC 2070 Board Sources of Error When making thermocouple measurements with the SC 2070 board and an MIO 16 board the possible sources of error are compensation linearization measurement and thermocouple wire errors Compensation error can arise from two sources inaccuracy of the temperature sensor and temperature differences between the sensor and the screw terminals The sensor used on the SC 2070 board is specified to be accurate to 1 C Minimize temperature differences between the sensor and the screw terminals by keeping the SC 2070 board away from drafts heaters and warm equipment Linearization error is a consequence of the polynomials being approximations of the true thermocouple output The linearization error is dependent on the degree of polynomial used Table 2 4 lists the linearization errors for the NBS polynomials Measurement error is the result of inaccuracies in the MIO 16 These inaccuracies include gain and offset If the board is properly calibrated the offset error should be zeroed out The only remaining error is a gain error of 0 08 of full range see the MIO 16 specifications If the input range 1s 10 V and the gain is 500 gain error contributes 0 0008 x 20 mV or 16 uV of error If the Seebeck coefficient of a thermocouple is 32 uV C this measurement error adds 0 5 C of uncertainty to the measurement For bes
34. 3 lists the voltage extremes from several popular thermocouple types Use this table as a guide for determining the best gain and input range settings to use SC 207X Series User Manual 2 16 National Instruments Corporation Chapter 2 SC 2070 Board Table 2 3 Thermocouple Voltage Output Extremes mV wemarerc mesarerc Tare 0 000 at 0 C 18 612 at 1760 C 0 000 at 0 C 21 006 at 1760 C 0 003 at 20 C 13 814 at 1820 C Source of information is Omega Temperature Measurement Handbook amp Encyclopedia Omega Engineering Stamford CT All temperatures are the difference between the measuring end and the cold junction or SC 2070 screw terminals in this case Linearizing the Data Thermocouple output voltages are highly nonlinear The Seebeck coefficient or voltage change per degree of temperature change can vary by a factor of three or more over the operating temperature range of some thermocouples For this reason the temperature from thermocouple voltages must either be approximated by polynomials or matched against a look up table The polynomial approach is easier to use but it trades measurement time for memory usage The polynomials are in the form T a0 ax aox gx Formula 2 4 where x is the thermocouple voltage in volts T is the temperature difference between the measuring end and the SC 2070 screw terminals in degrees Celsius and ao through a are coefficients specific to each thermocou
35. An Example of Using Thermocouples in Differential Mode 2 22 Single Ended Measuremk fits sius iia eve eate enne IIa a bacensneesdaatanestaatedancenventes 2 23 An Example of Using Thermocouples in Single Ended Mode 2 23 SOURCES OE EITOE ne uec dn ee ea e uu aed cn 2 24 Thermocouple Measurement ACCUracIes u 2 25 Additional Signal Connection Information ss 2 25 Chapter 3 5C 207 E BOAT oed etn iot Ota mea nds 3 1 Analog Inputs 2e rece etur quio pie aiv genti es EE Aedes diate a die dad 3 2 Temper ture Ses OF Se ne NT m uten Coen ipse eas 3 4 enidu guii M IL c 3 4 Fuse and Power LED eee nn es At re Ce Us ne 3 4 Digital and Timing Signals o ot pen ln taeda Pen a nas 3 5 Boardsto Board Cabins ni iro tiii tet ne aut aene iei tie at te 3 5 hires pM 3 7 Applications ne TR el eei tecta tse Co A en ie EEE 3 7 Soldering and Desoldering on the SC 2071 Board 3 7 Connecting Floating Signal Sources 3 8 Connecting Grounded Signal Sources ss 3 8 Building Lowpass Piltets 5o pe oe ee o qe eden E 3 8 Building Highpass PIlters en ie den neue ae eee 3 10 Building Attenuators Voltage Dividers 3 12 Working with THermocoupless s mor obese so e e t ho ers ipd ipe ha semis 3 14 Using the SC 2071 Board for Thermocouple Measurements eee 3
36. C 2050 cable adapter board the SC 2050 connects to the DAQ board with a 50 conductor ribbon cable The SC 2070 board then connects to the other 50 pin I O connector on the SC 2050 board For more information see Chapter 5 Installation and Connections Mounting The SC 2070 board is equipped with metal standoffs so the board can be placed on a workbench near the host computer You can use an optional rack mount chassis which can be fitted with a flat acrylic plastic cover When the SC 2070 board is mounted in the chassis the board can be grounded to its metal standoffs and therefore to the rack For more information see Chapter 5 Installation and Connections Applications The open component positions on the SC 2070 board make adding signal conditioning components to the analog input signals easier Several applications are covered in this section including thermocouple readings filtering and attenuation The figures in this section give examples on a specific input channel To install the circuit on a different channel see Table 2 1 to determine the equivalent component positions for the other channels Soldering and Desoldering on the SC 2070 Board The applications discussed here require modifications to the printed circuit board usually in the form of removing jumpers and adding components The SC 2070 board is shipped with wire jumpers in the E and F positions see Table 2 1 and Figure 2 2 Use a low wattage soldering iron 20
37. If the temperature sensor is chosen any signal conditioning that has been installed on channel 0 is ignored and has no effect Figure 3 3 shows the positions for jumper W1 a Channel 0 Selected b Temperature Sensor Selected Figure 3 3 W1 Jumper Settings Shield Ground Jumper W2 is used to connect digital ground DGND to a grounded metal case This option is useful only if the SC 2071 board is on metal standoffs and mounted in a grounded metal case You can select shield grounding to reduce noise Figure 3 4 shows the jumper settings for W2 W2 a Shield Ground Selected b Shield Ground Not Selected Figure 3 4 W2 Jumper Settings Fuse and Power LED The 5 V line from the DAQ device is protected by an 800 mA fuse If the red power LED does not light when the DAQ device is powered on check both the 800 mA fuse on the SC 2071 board and the output fuse if any on the Lab 1200 device Information on power connection is given in Chapter 5 Installation and Connections SC 207X Series User Manual 3 4 National Instruments Corporation Chapter 3 SC 2071 Board Digital and Timing Signals All of the signals from the Lab 1200 device are made available at screw terminals on the SC 2071 board Because these signals are not conditioned or changed in any way by this board refer to your Lab 1200 device user manual for information on the use of these signals If you want optical isolation of or relay control
38. National Instruments is NOT liable for damages or injuries resulting from these connections Installing the SC 205X Series Cable Adapter Boards Consult the SC 205X Series User Manual for instructions on installing your SC 205X Series board if any of these boards are being used SC 207X Series User Manual 5 2 National Instruments Corporation Chapter 5 Installation and Connections Installing the BNC 2081 Analog Breakout Board Consult your BNC 208X Series User Manual for instructions on installing your BNC 2081 board if this board is being used Rack Mounting Your SC 207X Series board can be installed on two thirds of a 19 in rack chassis You can mount one SC 207X Series board alongside an SC 205X Series cable adapter board or an SC 206X Series digital signal conditioning board Mount your SC 207X Series board on the left or right side of the 19 in rack mount The SC 207X Series board occupies two of the three mounting positions shown in Figure 5 1 f Left Hand Middle Right Hand Mounting Position Mounting Position Mounting Position Figure 5 1 Mounting Locations for SC 207X Series Boards Mount the SC 207X Series board in the chassis by removing the screws on the bottoms of the four standoffs attached to the board and using the same screws to attach the board to the mounting rack see Figure 5 2 lt Top Washers and Screw NS lt t Metal Standof
39. SA A2000 and some DAQCards The board comes with an optional DC to DC converter that converts the 5 V input into 15 V and 15 V for use by analog circuitry Detailed specifications of the SC 207X boards are in Appendix A Specifications National Instruments Corporation 1 1 SC 207X Series User Manual Introduction Chapter 1 Table 1 1 lists the specific DAQ devices that can currently be used with the SC 207X Series boards Table 1 1 DAQ Devices for Use with SC 207X Series Boards NB Series MC Series PC and AT Lab 1200 Series Other Macintosh IBM PS 2 Series PC XT AT and Devices PC XT AT Macintosh SC 2070 NB MIO 16 MC MIO 16 AT MIO 16 NB MIO 16X AT MIO 16D AT MIO 16F 5 AT MIO 16X AT MIO 64F 5 SC 2071 Lab LC Lab NB Lab PC DAQCard 12003 DAQPad 1200 PCI 1200 SC 2072 NB DIO 24 MC DIO 24 AT DIO 32F Lab LC NB DIO 32F MC DIO 32F AT MIO 16 Lab NB NB MIO 16 MC MIO 16 AT MIO 16D Lab PC PC OPDIO 16 NB MIO 16X AT MIO 16F 5 DAQCard 1200 AT MIO 16X DAQPad 1200 PC DIO 24 PCI 1200 PC DIO 96 PC LPM 16 PC TIO 10 1 2 Requires an NB5 cable available separately 3 Requires a PR50 50F cable available separately Requires an NB10 cable available separately All the signals from the DAQ board both analog and digital are made available at screw terminals Each of the SC 207X Series boards is connected directly to the DAQ board by a 50 pin ribbon cable If any SC 206X Series digital sig
40. SC 207X Series User Manual General Purpose Termination Breadboards November 1995 Edition Part Number 371173A 01 Copyright 1991 1995 National Instruments Corporation All Rights Reserved National Instruments Corporate Headquarters 6504 Bridge Point Parkway Austin TX 78730 5039 512 794 0100 Technical support fax 800 328 2203 512 794 5678 Branch Offices Australia 03 9 879 9422 Austria 0662 45 79 90 0 Belgium 02 757 00 20 Canada Ontario 519 622 9310 Canada Qu bec 514 694 8521 Denmark 45 76 26 00 Finland 90 527 2321 France 1 48 14 24 24 Germany 089 741 31 30 Hong Kong 2645 3186 Italy 02 48301892 Japan 03 5472 2970 Korea 02 596 7456 Mexico 95 800 010 0793 Netherlands 0348 433466 Norway 32 84 84 00 Singapore 2265886 Spain 91 640 0085 Sweden 08 730 49 70 Switzerland 056 200 51 51 Taiwan 02 377 1200 U K 01635 523545 Limited Warranty The SC 207X Series boards are warranted against defects in materials and workmanship for a period of one year from the date of shipment as evidenced by receipts or other documentation National Instruments will at its option repair or replace equipment that proves to be defective during the warranty period This warranty includes parts and labor A Return Material Authorization RMA number must be obtained from the factory and clearly marked on the outside of the package before any equipment will be accepted for warranty work National Instruments will pay the shi
41. SE input 2 8 SC 207X Series User Manual Index O optional equipment 1 4 P parts locator diagram SC 2070 board 2 2 SC 2071 board 3 2 SC 2072 board 4 2 SC 2072D board 4 3 physical specifications A 2 polynomial coefficients of National Bureau of Standards table 2 21 3 18 power connections external 5 4 to 5 5 amount of power supplied by DAQ devices table 5 6 SC 2072 board 4 4 to 4 5 accidental shorting of terminals at J4 warning 4 5 setting switch S2 to position B warning 4 4 switch S2 settings for National Instruments DAQ devices table 4 4 power LED SC 2070 board 2 4 SC 2071 board 3 4 SC 2072 board 4 5 power requirements from DAQ device A 1 R rack mount chassis cover attachment 5 9 rack mounting 5 3 to 5 4 referenced single ended input RSE 2 7 ribbon cable connectors 5 8 S SC 205X Series boards connections with SC 2070 and SC 2071 boards figure 5 7 SC 207X Series User Manual Index 4 connectors compatible with SC 207X boards table 5 8 installing 5 2 SC 207X Series boards See also specific devices computers supported 1 1 connections for DAQ devices figure 5 7 DAQ devices supported table 1 2 features 1 1 getting started 1 4 optional equipment 1 4 software 1 4 specifications A 1 to A 2 unpacking 1 5 SC 2070 board analog input 2 2 to 2 3 component positions in each channel table 2 3 onboard equivalent circuit figure 2 3 application
42. Table Table Table Table Table Table Table Table Table Table Table Table Table Table Contents Tables DAQ Devices for Use with SC 207X Series Boards 1 2 Component Positions in Each Channel 2 3 DAQ Boards Used with the SC 2070 Board sese 2 5 Thermocouple Voltage Output Extremes mV 2 20 NBS Polynomial Coefficients 1 namero tee petet pesas e eere arae aa e Ie Heg ee de epa e ve sess 2 2 Thermocouple Measurement Accuracies ss 2 25 Component Positions in Each Channel 3 3 DAQ Devices Used with the SC 2071 Board 3 5 Thermocouple Voltage Output Extremes mV esee 3 17 NBS Polynomial Gef fele ils anne etae tese Ua p RBRUM Nds 3 18 Thermocouple Measurement AOCCUFACIES esca ire doen e ed as eu een eoe Tode ee 3 2 Switch S2 Settings for National Instruments DAQ Devices 4 4 Amount of Power Supplied by DAQ Devices ss 5 6 SC 205X Series Board Connectors Compatible with the SC 207X Misure 5 8 National Instruments Corporation ix SC 207X Series User Manual About This Manual This manual describes the mechanical and electrical aspects of the SC 2070 SC 2071 and SC 2072 boards and contains information about installing and making connections to the boards The SC 207X Series boards are general purpose termination breadboards These breadboards connect to the National Instruments multifunct
43. The SC 2070 and SC 2071 boards are two general purpose breadboards with signal labeled screw terminals and temperature sensor breadboard and analog signal conditioning areas The SC 2070 and SC 2071 boards can be used for analog signal conditioning on the Macintosh IBM PS 2 Micro Channel and IBM PC XT AT computers The SC 2070 and SC 2071 breadboards simplify the connection of analog and digital signals to the DAQ board in laboratory test and production environments Up to seven thermocouples can be connected to each SC 2070 or SC 2071 board while using one channel to monitor the onboard temperature sensor for cold junction compensation The temperature sensor can be disconnected to make all eight differential or 16 single ended analog input channels available on the board The boards have silkscreened component locations for resistors and capacitors for building single pole highpass and lowpass filters voltage dividers and broken thermocouple detectors The SC 2070 and SC 2071 boards also have a general purpose breadboard area for building custom analog digital and timing circuits The SC 2072 board is a general purpose breadboard with screw terminals and a breadboard area that can be used for building custom analog digital and timing circuits The SC 2072 can be used with all National Instruments NB Series MC Series PC Series AT Series Lab 1200 Series and the PC OPDIO 16 DAQ digital I O and timing boards except the NB A2000 and the EI
44. User Manual 2 16 National Instruments Corporation Chapter 2 SC 2070 Board Using the SC 2070 Board for Thermocouple Measurements The maximum voltage level generated by thermocouples is typically a few millivolts Therefore an MIO 16 with high gain MIO 16L should be used for best resolution Thermocouples can be measured in either differential or single ended configurations Differential configuration has better noise immunity but single ended configuration has twice as many inputs The MIO 16 board must have a ground reference because thermocouples are floating signal sources Therefore use bias resistors if the board is in differential mode For single ended configuration use the referenced single ended input configuration Cold junction compensation with the SC 2070 board is accurate only if the temperature sensor reading is close to the actual temperature of the screw terminals Therefore when thermocouples are being read keep the SC 2070 board away from drafts or other temperature gradients such as those caused by heaters radiators fans and very warm equipment Input Filtering and Broken Thermocouple Detection Optional To reduce noise a lowpass filter can be connected Refer to Building Lowpass Filters earlier in this chapter for an explanation of how to design these filters Broken thermocouple detection circuitry is built by connecting a high value resistor between the positive input and 5 V The value of this resistor i
45. X Series board the DAQ device or the host computer High voltage can also cause an electric shock hazard to you National Instruments is NOT liable for damages or injuries resulting from these connections Hardware Installation for the SC 2072 The following are general instructions for installing your SC 2072 board in your computer DAQ system Consult your computer s user manual or technical reference manual for specific instructions and warnings Caution Turn the host computer off before making any connections 1 Mount the SC 2072 board into a 19 in rack optional 2 Connect the SC 2072 board to the DAQ device using a 50 pin ribbon cable If an SC 205X Series board is used with the SC 2072 board install and mount the SC 205X Series board as instructed in the SC 205X Series User Manual then connect the SC 2072 board to the SC205X Series board using the 50 pin cable and connect the SC 205X Series board to the DAQ device Connect field signals to the SC 2072 board at the screw terminals Attach the appropriate cover to the rack mount optional Turn the computer on Mr MR A When finished turn off any powered external signals to the SC 2072 board before turning off the computer Warning The SC 207X Series boards have not been designed for use with high voltage Input voltages larger than 42 V can result in damage to the SC 2072 the DAQ device or the host computer High voltage can also cause an electric shock hazard to you
46. age numbers and describe the errors Thank you for your help Name Title Company Address Phone Mail to Technical Publications Fax to Technical Publications National Instruments Corporation National Instruments Corporation 6504 Bridge Point Parkway 512 794 5678 Austin TX 78730 5039 Glossary AIGND CJC dB DC DGND DIFF GND Hz in I O LED LSB MB NBS NRSE PS 2 RSE S N SSR VDC National Instruments Corporation degrees ohms percent pi amperes alternating current analog to digital converter analog input ground Celsius cold junction compensation decibels direct current digital ground differential input mode farads cutoff frequency ground hertz inches input output kilobytes light emitting diode least significant bit meters megabytes of memory National Bureau of Standards nonreferenced single ended input mode Personal System 2 referenced single ended input mode signal to noise solid state relay volts volts direct current watts Glossary 1 SC 207X Series User Manual Index A accuracy of thermocouple measurements SC 2070 board 2 25 SC 2071 board 3 20 to 3 21 analog input SC 2070 board 2 2 to 2 3 component positions in each channel table 2 3 onboard equivalent circuit figure 2 3 SC 2071 board 3 2 to 3 3 component positions in each channel table 3 3 onboard equivalent circuit figure 3 3 s
47. ally thermocouple wire error is the result of inconsistencies in the thermocouple manufacturing process These inconsistencies or nonhomogeneities are the result of defects or impurities in the thermocouple wire The errors vary widely depending on the thermocouple type and even the gauge of wire used but a value of 2 C is typical For best results use an average of about 100 readings When averages are used typical accuracies are about 2 C Thermocouple Measurement Accuracies Table 3 5 lists the expected thermocouple accuracies in degrees Celsius subject to the following conditions e The Lab 1200 device is correctly calibrated e The temperature of the screw terminals equals the temperature of the device no gradients on the device The uncertainties listed apply at either 0 C Type J K E T or 600 C Type S R The linearization errors of the NBS polynomials in Table 3 4 measurement error of a calibrated Lab 1200 device and the 1 C cold junction sensor error are all included Thermocouple wire error is neglected because of dependence on several factors as listed above Finally these uncertainties are for the gain listed with a 5 V input range SC 207X Series User Manual 3 20 National Instruments Corporation Chapter 3 SC 2071 Board Table 3 5 Thermocouple Measurement Accuracies Lm 3 5 5s Additional Signal Connection Information For more information about signal conne
48. als A 4 by 1 5 in general purpose breadboard area is also included The SC 2071 board also has screw terminals for all of the other signals from the DAQ device With these terminals the board easily connects to digital timing and trigger signals The SC 2071 has two 50 pin I O connectors J1 and J2 Connector J2 is designated for daisy chaining DAQ signals Figure 3 1 shows the parts locator diagram for the SC 2071 board National Instruments Corporation 3 1 SC 207X Series User Manual Chapter 3 SC 2071 Board wr ew ZI Te O OO OO OJO O O O O O O QOOOOO0OOOOOO00000000000000000000000000000 DO00000000000000000000000000000000000000 0000900000000000000000000000000000 000000000000000000000000000000000 000000000000000000000000000000000 000000000000000000000000000000000 000000000000000000000000000000000 000000000000000000000000000000000000 0000000000000000000000000000000000000 0000000000000000000000000000000000000 00000000000000000000000000000000000000 0000000000000000000000000000000000000000 9000000000000000000000000000000000000000 o o o o o o o o 0000000000 0000000000 0000000000 ON9Q DOO000000000000000000000000000000000000000 o QN906 O o u o Lo a 09d Qu amp o Lo ebd O Fo o Foo bud O e 0 M a 5 Jt o Lo 9Ud O Fo o Fo 08d J9
49. als are accurate only within the temperature ranges specified Also all terms must be included to achieve the specified accuracy To avoid the long computation time required for these high order polynomials you can subdivide the operating range of a thermocouple into several smaller ranges Each of the smaller ranges can then be approximated by a much lower order polynomial such as the polynomial in Formula 3 6 Further examples of polynomials including lower order polynomials for subdivided temperature ranges can be found in NIST Monograph 175 Temperature Electromotive Force Reference Functions and Tables for the Letter Designated Thermocouple Types Based on the ITS 90 National Institute of Standards and Technology Gaithersburg MD 20899 Measurement Connections Connect the temperature sensor to channel 0 by configuring jumper W1 as shown in Figure 3 3 Connect the positive leads of the thermocouples to any SC 2071 board input channels except CHO Connect the negative leads to AIGND Notice that some thermocouples such as those from Omega Engineering Stamford CT have red insulation on the negative terminal Check with the vendor to determine the output polarity of any particular thermocouple For more information about signal sources and their connections see Chapter 2 in your Lab 1200 device user manual SC 207X Series User Manual 3 16 National Instruments Corporation Chapter 3 SC 2071 Board An Example of Using Thermocou
50. apacitor first and letting its value determine the resistance required is preferable because more standard resistor values are available If a capacitance of 1 uF is available the resistance is by substitution into Formula 2 1 39 789 Q or about 39 8 KO Divide this resistance by two to get the resistor value on each input of a differential channel Therefore in this example each input has a 19 89 KQ resistor or closest standard value in its series positions E and F The closest standard 5 tolerance resistors are 20 kQ The closest standard 0 5 resistors are 19 8 kQ National Instruments recommends using 1 or better tolerance resistors in this application because differences between the resistor values degrade the common mode rejection ratio Figure 2 9 shows both the schematic and the component placement for a 4 Hz lowpass filter placed on differential input channel 1 If the input signal source is floating place a bias return resistor in the D position R O in this case SC 207X Series User Manual 2 10 National Instruments Corporation Chapter 2 SC 2070 Board The SC 2070 board open component locations do not facilitate RC lowpass filters with the MIO 16 board configured for single ended inputs Therefore if the MIO 16 board is configured for single ended inputs lowpass filters must be built on the custom breadboard area Component Positions R12 Channel 9 in Channel 1 in R9 19 8
51. ard National Instruments Corporation 3 5 SC 207X Series User Manual SC 2071 Board Chapter 3 BNC 2081 Lab 1200 Device SC 2071 Figure 3 6 Daisy chaining a Lab 1200 device to a BNC 2081 For digital signal conditioning with the National Instruments SC 206X Series boards the SC 2053 cable adapter board must be used with the Lab NB or Lab PC Figure 37 shows a connection using the SC 2053 cable adapter board SC 2071 50 Conductor Cable SC 206X Series eot Port B Lab 1200 Device SC 2053 SC 206X Series i c Digital I O SC 206X Series Figure 3 7 Connection between a Lab 1200 device and the SC 2071 Board via the SC 2053 Board SC 207X Series User Manual 3 6 National Instruments Corporation Chapter 3 SC 2071 Board Warning Do not connect the SC 2071 board to any device other than a National Instruments Lab 1200 device or the SC 2053 cable adapter board The SC 2071 board is not compatible with any other DAQ devices or cable adapter boards Attempts to use the SC 2071 board with products for which it was not intended can result in damage to the SC 2071 board the DAQ device or the host computer National Instruments is NOT liable for damages resulting from these connections The SC 2071 board uses a 50 pin ribbon cable connector to connect to the 50 pin I O connector on either a Lab 1200 device an SC 2053 cabl
52. by the digital I O lines you must use a National Instruments SC 2053 cable adapter board and the appropriate SC 206X Series digital signal conditioning board For more information on these products refer either to your National Instruments catalog the SC 205X Series User Manual or the SC 206X Series User Manual Board to Board Cabling The SC 2071 board connects directly to any of the DAQ devices listed in Table 3 2 Table 3 2 DAQ Devices Used with the SC 2071 Board Lab 1200 Device PC XT and Macintosh SC 2071 Board LabLC Lab NB Lab PC Lab PC DAQCard 1200 2 DAQPad 1200 PCI 1200 Requires an NB10 cable available separately Requires a PR50 50F cable available separately The SC 2071 board has two functionally equivalent 50 pin I O connectors Connect one connector directly to the Lab 1200 device or to the SC 2053 cable adapter board with the included 50 conductor NB1 cable A direct connection is shown in Figure 3 5 If you are using the SC 2071 board with the Lab LC board an NB10 cable connects the Lab LC board to the SC 2071 board If you are using the SC 2071 board with the DAQCard 1200 a PR50 50F cable connects the DAQCard 1200 to the SC 2071 board The second connector is used for daisy chaining to the BNC 2081 as shown in Figure 3 6 50 Pin I O Connectors 50 Conductor cable Lab 1200 Device i SC 2071 Figure 3 5 Direct Connection between a Lab 1200 device and the SC 2071 Bo
53. ce falls into the floating signal source category Some examples of floating signal sources are outputs for thermocouples transformers battery powered devices optical isolators and isolation amplifiers The ground reference of a floating source must be tied to the ground of the DAQ board to establish a local or onboard reference for the signal Differential Inputs To provide a return path for the instrumentation amplifier bias currents floating sources must have a 10 to 100 KQ resistor to AIGND on one input if DC coupled or both inputs if AC coupled For more detailed information on connections to floating signal sources and differential inputs refer to the configuration chapter in your MIO 16 board user manual These bias resistors can be installed in positions B and D Table 2 1 and Figure 2 2 of the SC 2070 board Figure 2 7 shows both the schematic and the component placement for a single 100 KQ bias return resistor on the negative input from a floating source connected to channel 1 the D position in Table 2 1 Additional signal conditioning circuitry such as filters and attenuators described in Building Lowpass Filters Building Highpass Filters and Building Attenuators later in this chapter can be built in the open component positions National Instruments Corporation 2 7 SC 207X Series User Manual SC 2070 Board Chapter 2 Component Position R10 Channel 9 in Q2 Channel 1 7 Jumpers in
54. connected to the relays can exceed 42 V National Instruments Corporation 5 9 SC 207X Series User Manual Appendix A Specifications This appendix contains specifications for the SC 207X boards These specifications are typical at 25 C unless otherwise noted Analog Input Number of channels ts Eight differential 16 single ended Field connections seen 36 labeled or numbered screw terminals with direct connection to all analog and digital signals on multifunction DAQ board Cold junction temperature sensor ACCURACY aite t lash Ghee 0 5 C from 0 to 110 C Output st tbe erm ER eed 10 mV C jumper selected on channel 0 Compensation siess esir nene rore nennen nennen Performed by software on host computer Conditioning capability eee Seven open component positions per channel that include connections from each input to ground 5 V each other and series connections to the inputs of the DAQ boards Breadboarding Area SC 2070 and SC 2071 1 ore REDDE 10 2 by 3 8 cm 4 0 by 1 5 in 8SC 2072 niae entere eterne rs 10 9 by 7 6 cm 4 3 by 3 0 in F edthrough 126 5 eot eee ee ei editori 0 09 cm 0 0351 in diameter on 0 25 cm 0 1 in center spacing hn nt mine nine Eight undedicated screw terminal connections 40 feedthroughs connected to 5 VDC 40 feedthroughs connected to ground Voltage available nn ananas 5 V and DGND on two bus strips Power Requirement from DAQ board 45 MDC itai
55. crylic plastic cover For more information see Chapter 5 Installation and Connections Soldering and Desoldering on the SC 2072 Board Use a low wattage soldering iron 20 to 30 W when soldering to the board To desolder on the SC 2072 vacuum type tools work best Use care when desoldering to avoid damaging component pads Only use rosin core electronic grade solder Acid core solder damages the printed circuit board and components National Instruments Corporation 4 7 SC 207X Series User Manual Chapter 5 Installation and Connections This chapter explains how to install and make connections to the SC 207X Series boards Hardware Installation Most of the sections that follow apply to all of the SC 207X Series boards However several topics are more board specific than others Unless a given topic is delineated by board the topic applies to all SC 207X Series boards Hardware Installation for the SC 2070 and the SC 2071 The following are general instructions for installing your SC 2070 or SC 2071 board in your computer DAQ system Consult the user manual or technical reference manual of your computer for specific instructions and warnings Caution Turn the host computer off before making any connections 1 Determine what signal conditioning is desired for the analog inputs and install the necessary components into the open component positions If no signal conditioning is needed on an input then the factory installed jump
56. ction refer to Chapter 2 in your Lab 1200 device user manual National Instruments Corporation 3 2 SC 207X Series User Manual Chapter 4 SC 2072 Board This chapter describes the SC 2072 board in detail including function connection mounting and soldering desoldering The SC 2072 board comes in two configurations the SC 2072 comes without a DC to DC converter whereas the SC 2072D comes with a DC to DC converter Unless the text denotes otherwise all references to the SC 2072 board apply to both configurations The SC 2072 is a general purpose termination breadboard that makes it easy to connect to all NB Series MC Series PC Series AT Series Lab 1200 Series and the PC OPDIO 16 DAQ digital I O and timing devices except for the NB A2000 and the EISA A2000 and some DAQCards add analog input signal conditioning such as filters and dividers and build external custom timing analog and digital circuits The SC 2072 board is used with the National Instruments DAQ devices for the Macintosh IBM PS 2 Micro Channel and PC XT AT and compatible computers The SC 2072 board has screw terminals for all 50 signals present on the I O cable These terminals can be used for easy connection to the analog digital timing and trigger signals from the expansion board In addition the SC 2072 board has one set of 12 terminals that can be used for connection of 12 external signals For digital power connections one set of three termi
57. ction can attach to the SC 2071 board 50 pin male connectors One of these must attach to the SC 205X Series boards host DAQ device The other connection can attach to the SC 2072 board Warning Do not attempt to connect an SC 207X Series board to any connector for which it is not designed Such connections can result in damage to any or all of the boards connected to the SC 207X Series board to the host computer and to the SC 207X Series boards themselves National Instruments is NOT liable for any damages resulting from such misuse Screw Terminal Connections for the SC 2070 and the SC 2071 The SC 2070 and SC 2071 boards supply analog input to the host computer via the DAQ device via the screw terminals along one edge of the board The remaining signals from the DAQ device are available at screw terminals on the other side of the board Additionally eight undedicated screw terminals are located adjacent to the general purpose breadboarding area Guidelines for connections to the analog input terminals are given in Chapters 2 and 3 Warning Connections including power signals to ground and vice versa that exceed any of the maximum input or output voltage ratings on the SC 207X Series boards can result in damage to any or all of the boards connected to the SC 207X Series boards to the host computer and to the SC 207X Series boards Overvoltage conditions also can present a shock hazard to you National Instruments is NOT liable for
58. d the ground lines of the supply to the screw terminals labeled 5 V and GND on the board To connect the external analog power supply the power supply must be turned off to the SC 2072 connect the wires from the positive ground and negative supply outputs to the screw terminals labeled V COM and V respectively National Instruments Corporation 5 5 SC 207X Series User Manual Installation and Connections Chapter 5 Table 5 1 shows the amount of power that each DAQ device can supply to external accessories Use this table to determine if any accessory boards need to be powered by an external supply Table 5 1 Amount of Power Supplied by DAQ Devices Board Allotted Power by Slot Power Used Power from Board Available for Accessories AT DIO 32F AT MIO 16 AT MIO 16D AT MIO 16F 5 AT MIO 16X AT MIO 64F 5 Lab PC Lab PC DAQCard 1200 DAQPad 1200 PCI 1200 Not Specified Not Specified Not Specified Not Specified Not Specified Not Specified Not Specified Not Specified 1 0A 1 5A PC DIO 24 Not Specified PC DIO 96 Not Specified PC LPM 16 Not Specified PC TIO 10 Not Specified MC DIO 24 MC DIO 32F MC MIO 16 Lab LC Lab NB NB DIO 24 NB DIO 32F NB MIO 16 NB MIO 16X DAQCard 700 1 0A 0 12A 0 88 A DAQCard DIO 24 1 0A 0 1A 0 9 A The allocated power by slot is not specified on the XT and AT bus and depends on the power supply capacity and the power used by other boards installed in your system These lim
59. d to the SC 2070 board 50 Pin I O Connectors SC 2070 50 Conductor cable Figure 2 5 Direct Connection between an MIO 16 Board and the SC 2070 Board If any signal conditioning of the digital I O ports with the National Instruments SC 206X Series boards is desired then the SC 2050 cable adapter board must be used with the DAQ boards listed in Table 2 2 Figure 2 6 shows a connection using the SC 2050 cable adapter board SC 2070 50 Conductor Cable Digital I O SC 2050 or SC 206X Series 26 Conductor Cable 8 Channel SSR Figure 2 6 Connection between an MIO 16 Board and the SC 2070 Board via the SC 2050 Board National Instruments Corporation 2 5 SC 207X Series User Manual SC 2070 Board Chapter 2 Warning Do not connect the SC 2070 board to any board other than a National Instruments MIO 16 board or the SC 2050 cable adapter board The SG2070 board is not compatible with any other DAQ boards or cable adapter boards Attempts to use the SC 2070 board with products for which it is not intended can result in damage to the SC 2070 board the DAQ board or the host computer National Instruments is NOT liable for damages resulting from these connections The SC 2070 board uses a 50 pin ribbon cable connector to connect to the 5Gpin I O connector on either a DAQ board or the SC 2050 cable adapter board If you are using the S
60. dboard Area Fuses Figure 4 1 SC 2072 Board Parts Locator Diagram SC 207X Series User Manual 4 2 National Instruments Corporation Chapter 4 SC 2072 Board o o cA o d loca SC 207e 000000000000000 ASSY181310 0 REV A 0000000000000000000 000000000000 299999900090090 000 000000000000 INTERNAL POWER SELECTIONS 00000000 000 o 00000000000 52 POSITIONS 0000000000 A 50 J2 PIN 49 J8 PIN 50 N C N C V J2 PIN 34 J2 PIN 33 PHR aga POWER SELECTOR OOOOOOOOOOOH 000000000000 U 000000000000000 000000000000000 000000000000000 000000999000000 COM General Purpose Screw Block Terminals Connector J5 Switch S2 DC to DC Converter External Power Screw Block Terminals Connector J3 Screw Block Terminals for I O Connector Signals Connector J3 Switch S1 50 pin I O Connector General Purpose Breadboard Area Fuses Figure 4 2 SC 2072D Board Parts Locator Diagram Signal Connections The SC 2072 board is equipped with one 50 pin cable connector one 50 position screw terminal block and one 12 position screw terminal block Each of the 50 signals located on the cable
61. e AT Read and AI Scale functions to do the reading The temperature sensor voltage is 10 mV C so the gain should be either 1 or 10 10 for the best resolution Multiply the voltage by 100 to get the SC 2070 temperature in degrees Celsius For example if the reading is 0 25 V the SC 2070 board is at 25 C 2 Read the voltage on analog input channel 1 using a gain of 500 If you are using an NI DAQ software package you can use the AT Read and AT Scale functions to read the channel 3 Translate the reading into an uncompensated temperature using either a look up table or a polynomial such as that described in Formula 2 4 For example assume that the reading from the thermocouple is 9 39 mV By applying Formula 2 6 and the coefficients from Table 2 4 you can calculate that the uncompensated temperature is 175 C 4 Add the cold junction temperature from step 1 to the uncompensated temperature obtained in step 3 This result is the temperature at the measuring end of the thermocouple For the example given the temperature of the boiler system is 175 C 25 C 200 C National Instruments Corporation 2 21 SC 207X Series User Manual SC 2070 Board Chapter 2 Single Ended Measurements Connect the temperature sensor to channel 0 by configuring jumper W1 as shown in Figure 2 3 Connect the positive leads of the thermocouples to any SC 2070 input channels except CHO Connect the negative leads to AIGND Notice that some th
62. e adapter board or the BNC 2081 analog breakout board If the SC 2053 cable adapter board is being used the SC 2053 connects to the DAQ device with a 50 conductor ribbon cable The SC 2071 board then connects to the other 50 pin I O connector on the SC 2053 If you are using the BNC 2081 analog breakout board connect the BNC 2081 to the SC 2071 board with a 50 conductor ribbon cable Make sure you do not connect voltage signals to the same analog input or analog output channels on both the SC 2071 and the BNC 2081 For more information see Chapter 5 Installation and Connections Mounting The SC 2071 board is equipped with metal standoffs so the board can be placed on a workbench near the host computer You can use an optional rack mount chassis which can be fitted with a flat acrylic plastic cover When the SC 2071 board is mounted in the chassis the board can be grounded to its metal standoffs and therefore to the rack For more information see Chapter 5 Installation and Connections Applications The open component positions on the SC 2071 board make adding signal conditioning components to the analog input signals easier Several applications are covered in this section including thermocouple readings filtering and attenuation The figures in this section give examples on a specific input channel To install the circuit on a different channel consult Table 3 1 to determine the equivalent component positions for the other channel
63. e and Power LBD a ns sn ose a p nei alti dees 2 4 Disitaland Timing SIgnalsc su ns tt Sn an en a etes ttes in nie tre gnus 2 4 Board to Board Cabling ceser riei a e huit 2 5 Mo ntin gsi na a T E A E E A A E e ede Mu etude 2 6 PSP CALLOUS Sen Gu oO E E A A A bou eu o rut e ron 2 6 Soldering and Desoldering on the SC 2070 Board 2 7 Channel Configurations aoc eh RSS Re ee aS 2 7 Connecting Nonreferenced or Floating Signal Sources 2 7 Differential Inpulsc Sn RS nn nn M tas M sus 2 7 single Ended Inpuls tee ee nas 2 8 Connecting Ground Referenced Signal Sources 2 9 Differential Inp ts i jicsissaccesisccsetssacsvaceite deacon thacssvaseesndeesnncceds sbovesvadeasacdededs 2 9 SueglesBnded Ipso oasis ee OR E RU Da oua adeo a MES IRE P Uc OL eine 2 9 Building Lowpass Filters unanimement 2 10 Building Hiehpass PUGES ese intere ona eo teo nt tn titane 2 13 Building Attenuators Voltage Dividers 2 15 Working with Thermocouples 0053 sn dius Etpa ord demde o datu m t MON eei 2 17 Using the SC 2070 Board for Thermocouple Measurements eese 2 17 Input Filtering and Broken Thermocouple Detection Optional 2 18 Selecting the Gain and Input Ranges ue ede ardent 2 19 Ia3neatizimg the Data su ocio eoo ge aceto pd Se Te nn quisi 2 20 National Instruments Corporation v SC 207X Series User Manual Contents Differential Measurements iiia d opea tup tee reine 2 22
64. e using the digital supply and the red power LED does not light when the expansion board or external power supply is powered on check both the SC 2072 fuses and the output fuse if any on the expansion board or the power supply More information on connecting power is given in Chapter 5 Installation and Connections National Instruments Corporation 4 5 SC 207X Series User Manual SC 2072 Board Chapter 4 Board to Board Cabling The SC 2072 board connects directly to all NB Series MC Series PC Series AT Series Lab 1200 Series and the PC OPDIO 96 DAQ digital I O and timing devices except for the NB A2000 and the EISA A2000 and some DAQCards The various expansion devices connect to the SC 2072 board as shown in Figure 4 3 50 Pin I O Connectors SC 2072 50 Conductor cable Figure 4 3 Direct Connection between a TIO 10 Board and the SC 2072 Board If you want any signal conditioning of the digital I O ports with the National Instruments SC 206X Series boards you can use an SC 205X Series cable adapter board The SC 2050 can be used with any MIO 16 The SC 2051 can be used with any DIO24 or with a PC DIO 96 that is equipped with a PC DIO 96 to DIO 24 converter The SC 2052 can be used with any DIO 32F The SC 2053 can be used with either the Lab NB the Lab LC the Lab PC or the Lab PC Figure 4 4 shows a connection using the SC 2051 cable adapter board SC 2072 50 C
65. ed to an MIO T6 Bof toii PN aire MR eau ru OS 1 3 SC 2070 Board Parts Locator Diagram 2 2 Onboard Equivalent Circ lt s isse peter cadet dede edu opu be bec depen ce 2 3 MNT Jumper SERRES o ade Lese qim oed bat esame pL make tm bs ie 2 4 W2 Jumper Stt DS oree sd re dato see tha Sa ugly dette ude ou cot oue ate 2 4 Direct Connection between an MIO 16 Board and the SC 2070 Board 2 5 Connection between an MIO 16 Board and the SC 2070 Board via the 5C 2030 BOARD re ee dium ne boite ed mL LM De 2 6 Bias Return Resistor for DC Coupled Floating Source on Channel 1 2 8 Normalized Frequency Response of Lowpass Filter 2 10 Lowpass Filter on Differential Channel 1 2 12 Normalized Frequency Response of Highpass Filter 2 13 Highpass Filter on Differential Channel 1 2 14 Attenuator for Use with Differential Inputs eene 2 16 Thermocouple Circuit with Open Thermocouple Detect and Lowpass INOISC PSE o ass dette coget balada qus ES DOR eN OAM cem veneto da cA edm MELDE 2 19 SC 2071 Board Parts Locator Diagram 3 2 Onboard Equivalent Circuit esee niet eh roe eaa PUE endet na IY eS 3 3 ANT Jumper Setting S sh ins en sd ace Du Sees UE qe PEN MONI DU suisse 3 4 WY CPUS Settings coca ood Hiat etu Me EN UAE ME eS LP IDE 3 4 Direct Connection between a Lab 1200 Device and the SC 2071 Board
66. ed to measure temperature You only need to know the temperature of the screw terminal junctions to compensate for all dissimilar metal junctions in a system with constant temperature Thermocouple Law of Intermediate Metals Therefore if you know the temperature at the screw terminals you can easily calculate the temperature at the point of interest from the voltage measured A National Semiconductor LM 35CZ is used on the SC 2070 board to determine the temperature of the screw terminals The dissimilar metal junctions at the screw terminals are also referred to as the cold junction The process of using the known temperature at that point to find the temperature at the unknown point is called cold junction compensation CJC Thermocouples are usually more desirable than direct reading sensors for several reasons Thermocouples are more rugged than most other sensors and can tolerate several hundred degree temperatures without degradation Semiconductor sensors the easiest to use usually cannot be used above 70 C Thermocouples are inexpensive and physically small so they can track temperature changes rapidly Thermocouple output voltages are very low on the order of 50 uV C The temperature coefficient changes with temperature resulting in a nonlinear curve The temperature can be determined from tables available from thermocouple vendors or calculated from polynomial equations such as those given in the next section SC 207X Series
67. el 0 The MIO 16 board can be configured for either differential or single ended inputs if this temperature sensor is used Jumper W1 is used to select either the temperature sensor or the external screw terminals as the input source for differential channel O If the temperature sensor is chosen any signal conditioning that has been installed on channel 0 is ignored and has no effect Figure 2 3 shows the positions for jumper W1 National Instruments Corporation 2 3 SC 207X Series User Manual SC 2070 Board Chapter 2 a Channel 0 and b Temperature Sensor c Temperature Sensor Channel 8 Selected Selected Selected Differential Inputs Single Ended Inputs Figure 2 3 W1 Jumper Settings Shield Ground Jumper W2 is used to connect digital ground DGND to a grounded metal case This option is useful only if the SC 2070 board is on metal standoffs and is mounted in a grounded metal case Select shield grounding to reduce noise Figure 2 4 details the jumper settings for W2 W2 a Shield Ground Selected b Shield Ground Not Selected Figure 2 4 W2 Jumper Settings Fuse and Power LED The 5 V line from the DAQ board is protected by an 800 mA fuse If the red power LED does not light when the DAQ board is powered on check both the 800 mA fuse on the SC 2070 board and the output fuse if any on the MIO 16 board See Chapter 5 Installation and Connections for information on connecting power Digital
68. ember to turn the host computer off before making any connections One end of the ribbon cable connects to the SC 207X Series board at connector J1 SC 2070 and SC 2071 or J2 SC 2072 The other end connects either to the DAQ device or to one of the two 50 pin headers on the SC 205X Series board you installed for use with the DAQ device National Instruments Corporation 5 7 SC 207X Series User Manual Installation and Connections Chapter 5 Signal Connections Ribbon Cable Connectors The pinout for the 50 pin ribbon cable connector on the SC 2070 board is exactly the same as the 50 pin connector on the MIO 16 board The pinout for the 50 pin ribbon cable connector on the SC 2071 board is exactly the same as the 50 pin connector on the Lab 1200 device The pinout for the 50 pin ribbon cable connector on the SC 2072 board is exactly the same as the 50 pin connector on the host DAQ device For more information on these connectors refer to your DAQ device s user manual Table 5 2 lists SC 207X Series compatibility with the SC 205X Series boards Table 5 2 SC 205X Series Board Connectors Compatible with the SC 207X Series Boards Connectors Connections Description 50 pin male connectors One of these must attach to the SC 2050 for MIO 16 boards host MIO 16 board The other connection can attach to the SC 2070 board 50 pin male connectors One of these must attach to the SC 2053 for Lab 1200 boards host Lab 1200 board The other conne
69. ents helps us help you better and faster National Instruments provides comprehensive technical assistance around the world In the U S and Canada applications engineers are available Monday through Friday from 8 00 a m to 6 00 p m central time In other countries contact the nearest branch office You may fax questions to us at any time Corporate Headquarters 512 795 8248 Technical support fax 800 328 2203 Branch Offices Australia Austria Belgium Canada Ontario Canada Quebec Denmark Finland France Germany Hong Kong Italy Japan Korea Mexico Netherlands Norway Singapore Spain Sweden Switzerland Taiwan U K 512 794 5678 Phone Number 03 9 879 9422 0662 45 79 900 02 757 00 20 519 622 9310 514 694 8521 45 76 26 00 90 527 2321 1 48 14 24 24 089 741 31 30 2645 3186 02 48301892 03 5472 2970 02 596 7456 95 800 010 0793 0348 433466 32 84 84 00 2265886 91 640 0085 08 730 49 70 056 200 51 51 02 377 1200 01635 523545 National Instruments Corporation Fax Number 03 9 879 9179 0662 45 79 90 19 02 757 03 11 519 622 9311 514 694 4399 45 76 71 11 90 502 2930 1 48 14 24 14 089 714 60 35 2686 8505 02 48301915 03 5472 2977 02 596 7455 5 520 3282 0348 430673 32 84 86 00 2265887 91 640 0533 08 730 43 70 056 200 51 55 02 737 4644 01635 523154 B 1 SC 207X Series User Manual Technical Support Form Photocopy this form and update it each time you make changes
70. ermocouples such as those from Omega Engineering Stamford CT have red insulation on the negative terminal Check with the vendor to determine the output polarity of any particular thermocouple The MIO 16 board should be configured for ground referenced single ended inputs For more information about signal sources and their connections see Chapter 2 in your MIO 16 board user manual An Example of Using Thermocouples in Single Ended Mode Assume that you are measuring the temperature of a high pressure boiler system with a PC AT computer an AT MIO 16L in single ended mode an SC 2070 board and a J type thermocouple The maximum temperature that can be reached in this example is 300 C Before taking readings you must configure the AT MIO 16L board for the maximum resolution possible A thermocouple table shows that the output voltage never exceeds 16 to 17 mV recall that the exact voltage measured is a function of the SC 2070 temperature as well as the temperature being measured Therefore either a 5 V input range with a gain of 100 50 mV maximum signal or a 10 V input range with a gain of 500 20 mV maximum signal can be selected In this case the 10 V input range with a gain of 500 gives the best resolution Set the jumpers on the AT MIO 16L for single ended input 10 V input range Jumper W1 on the SC 2070 board is set to select the temperature sensor as shown in Figure 2 3 To connect the thermocouple to single ended channel 1
71. ers on the SC 2070 or jumper on the SC 2071 must be in place 2 Check that jumpers W1 and W2 are set correctly for the current application 3 Mount the SC 207X Series board into a 19 in rack optional 4 Connect the SC 207X Series board to the DAQ device using a 50 pin ribbon cable If an SC 205X Series board is used with the SC 207X Series boards install and mount the SC 205X Series board as instructed in the SC 205X Series User Manual then connect the SC 207X Series board to the SC 205X Series board using the 50 pin cable and connect the SC 205X Series board to the DAQ device 5 Connect field signals to the SC 207X Series board at the screw terminals 6 Attach the appropriate cover to the rack mount optional 7 Turn the computer on 8 When finished turn off any powered external signals to the SC 207X Series board before turning off the computer National Instruments Corporation 5 1 SC 207X Series User Manual Installation and Connections Chapter 5 Warning The SC 207X Series boards have not been designed for use with high voltage Although the open component positions are configured so that voltage dividers can be installed to reduce a high input voltage to within the DAQ device s 10 V input range the maximum safe input voltage at any point on the SC 207X Series boards is 42 V peak Input voltages larger than 42 V even if attenuated by a voltage divider on the SC 207X Series board can result in damage to the SC 207
72. f Circuit Board x Rack Mount 4 Washer amp Lock Washer lt t Screw Figure 5 2 Attaching a Mountable Board to the Chassis National Instruments Corporation 5 3 SC 207X Series User Manual Installation and Connections Chapter 5 Be sure to include the washers around the screws when attaching your board to the rack mount see Figure 5 2 Notice that jumper W2 can connect the digital ground for the SC 2070 and SC 2071 boards to the metal standoffs attached to the board Rack mounting does not automatically ground the board to the metal chassis unless jumper W2 is set If two SC 207X Series boards connected to different DAQ devices need to be stacked double height mounting within one rack mount chassis is possible Because only one SC 207X Series board can be used with each DAQ device this situation occurs only if two or more DAQ devices are being used You need a hardware kit for double height mounting see Optional Equipment in Chapter 1 consisting of two brackets that are installed in the rack mount A second row of boards can be mounted on these brackets in the same way the first row is mounted Figure 5 3 illustrates double height mounting Install racks for double height mounting First row of boards mount in bottom of rack mount chassis Second row of boards mounts on racks Figure 5 3 Double Height Mounting SC 207X Series User Manual 5 4 National Instruments Cor
73. ferencing the signal to AIGND can cause inaccurate measurements resulting from an incorrect ground reference National Instruments Corporation 2 9 SC 207X Series User Manual SC 2070 Board Chapter 2 Building Lowpass Filters Simple RC lowpass filters are easily installed in the SC 2070 board on any differential input channel The filters are useful for accurate measurement and noise rejection By substituting resistance and capacitance values into the following Formula hereafter referred to as Formula 2 1 you can calculate a simple one pole RC filter to have a 3 dB point cutoff frequency 1 f RO Formula 2 1 The frequency response rolls off at a rate of 20 dB per decade of increase thereafter A Bode plot of the amplitude versus normalized frequency is shown in Figure 2 8 Amplitude 1 0 1 0 01 100 1 000 10 000 Normalized Frequency Figure 2 8 Normalized Frequency Response of Lowpass Filter When measuring low frequency signals about 4 Hz if you have 400 Hz noise on your inputs you can add a lowpass filter with a cutoff frequency of 4 Hz The 400 Hz noise then attenuates by 40 dB Notice that your 4 Hz signal also attenuates but by only 3 dB Do not neglect any potential attenuation of signals of interest by this low order filter You must also choose the filter component values The resistance or the capacitance can be selected arbitrarily one value determines the other Picking the c
74. gle ended inputs and eight differential inputs For thermocouple and other low level applications best results are obtained when differential inputs are used For specific applications illustrating signal conditioning with both single ended and differential inputs refer to Applications later in this chapter SC 207X Series User Manual 2 2 National Instruments Corporation Chapter 2 SC 2070 Board Channel To Input Multiplexer Factory Installed Jumpers Channel Figure 2 2 Onboard Equivalent Circuit The components are numbered differently for each channel Table 2 1 lists the components in each channel and their correspondence to the circuit shown in Figure 2 2 Table 2 1 Component Positions in Each Channel Channel Position in Figure 2 2 Differential Single Channel A B C D F When the board is shipped jumpers are inserted in the E and F positions of the input network see Figure 2 2 These jumpers can be easily removed to build analog input signal conditioning circuits Several applications showing the use of these open component positions are discussed in Applications later in this chapter Temperature Sensor The SC 2070 board is equipped with an onboard temperature sensor for use with thermocouple cold junction compensation This sensor a National Semiconductor LM 35CZ generates a voltage output of 10 mV C with an accuracy of X1 C The sensor is jumper selected on differential input chann
75. ing abbreviations acronyms metric prefixes and symbols The ndex alphabetically list the topics in the manual including the page where you can find each one National Instruments Corporation xi SC 207X Series User Manual About This Manual Conventions Used in This Manual The following conventions are used in this manual bold bold italic italic monospace SC 206X Series DIO board DIO 24 DIO 32F Lab 1200 Series MIO 16 NI DAQ TIO 10 Bold text denotes menus menu items or dialog box buttons or options Bold italic text denotes a note caution or warning Italic text denotes emphasis a cross reference or an introduction to a key concept Text in this font is used for function names SC 206X Series refers to SC 2060 SC 2061 or SC 2062 boards DIO board refers to the NB DIO 24 NB DIO 32F NB DIO 96 MC DIO 24 MC DIO 32F PC DIO 24 ATDIO 32F and PC DIO 96 boards DIO 24 refers to the NB DIO 24 MC DIO 24 and PC DIO 24 boards DIO 32F refers to the NB DIO 32F MC DIO 32F and ATDIO 32F boards Lab 1200 Series refers to the Lab LC Lab NB Lab PC and Lab PC boards and the DAQCard 1200 DAQPad 1200 and PCIE 1200 devices MIO 16 refers to the NB MIO 16 NB MIO 16X MC MIO 16 AT MIO 16 ATMIO 16D AT MIO 16E5 and AT MIO 16X boards NI DAQ refers to the NI DAQ software for PC compatibles or Macintosh unless otherwise stated TIO 10 refers to the PC TIO 10 board Abbreviatio
76. ion data acquisition DAQ boards for the IBM PC XT AT Personal System 2 and compatible computers and Macintosh II computers Each of the SC 207X Series boards is described in detail in this manual Organization of This Manual The SC 207X Series User Manual is organized as follows e Chapter 1 Introduction describes the SC 207X Series boards lists what you need to get started describes the optional equipment and software and explains how to unpack your SC 207X Series board e Chapter 2 SC 2070 Board describes the SC 2070 board in detail including function compatibility connection mounting and applications This chapter also discusses working with thermocouples e Chapter 3 SC 2071 Board describes the SC 2071 board in detail including function compatibility connection mounting and applications This chapter also discusses working with thermocouples e Chapter 4 SC 2072 Board describes the SC 2072 board in detail including function connection mounting and soldering desoldering e Chapter 5 Installation and Connections explains how to install and make connections to the SC 207X Series boards e Appendix A Specifications contains specifications for the SC 207X Series boards e Appendix B Customer Communication contains forms you can use to request help from National Instruments or to comment on our products The Glossary contains an alphabetical list and description of terms used in this manual includ
77. ional Instruments products for or involving medical or clinical treatment must be performed by properly trained and qualified medical personnel and all traditional medical safeguards equipment and procedures that are appropriate in the particular situation to prevent serious injury or death should always continue to be used when National Instruments products are being used National Instruments products are NOT intended to be a substitute for any form of established process procedure or equipment used to monitor or safeguard human health and safety in medical or clinical treatment Contents About This MANQUE 8655 op deem MED LUE xi Orsanizationab This Manila zo dee i bees epis ted auod run a dedos deeds xi Conventions Used m This Manual eerie ta ra iae od ee ed adora de xii Related Documentation en costars e SR Re qehti qa es ts xii Customer COMMON su ocius ei se eut dein ee oo ne ses xiii Chapter 1 InfrodUCctoB os a es esl mE RD 1 1 Aboutthe SC 207 X Series BOSS nd D e MO ERG ede Pa PONE eS 1 1 What Y Gu Need to Get 5tabted aoa moe nd anne mie sb teet tie wh an geste 1 4 Opt onal Equipments iu cien tier v Ee ae Dae Oe nt RE Ve se but bes 1 4 SOO LL AL MR ER 1 4 Bir Spp MP E 1 5 Chapter 2 SC 2070 Board ES en outa 2 1 Analogs UP UC seio ou trio esed ucts eiie qud eie viva EP agen sutor goad eee ae tele 2 2 Temperature AI d 2 3 Shield Ground es Tex et nets ets or see pe rt nn 2 4 Fus
78. itations are caused by a series fuse on the 5 V out on these boards rather than the remaining power per slot The DIO 32F does not have a 5 V digital supply output All SSR Series modules require an external power supply when used with the DIO 32F SC 207X Series User Manual 5 6 National Instruments Corporation Chapter 5 Installation and Connections SC 207X Series Board Connection Figure 5 4 illustrates the connections from the SC 2070 or SG2071 boards directly to DAQ devices via a 50 conductor cable and to DAQ devices via the SC 205X Series boards Because the SC 2072 board is somewhat more flexible no connection scheme is outlined However the SC 2072 connection parallels that of the SC 2070 and SC 2071 SC 2070 50 Conductor Cable SC 2070 50 Conductor Cable Digital 1 O SC 2050 SC 206X Series BNC 2081 Lab 1200 Device SC 2071 50 Conductor Cable SC 2071 50 Conductor Cable SC 206X Series eot Port B Lab 1200 Device SC 2053 SC 206X Series SR Digital I O SC 206X Series Figure 5 4 Connections Between DAQ Devices and SC 205X Series Boards and Between SC 205X Series Boards and SC 2070 and SC 2071 Boards A 50 pin ribbon cable connects your SC 207X Series board to either an SC 205X Series board or directly to the DAQ device Rem
79. le for any delay in performance due to causes beyond its reasonable control The warranty provided herein does not cover damages defects malfunctions or service failures caused by owner s failure to follow the National Instruments installation operation or maintenance instructions owner s modification of the product owner s abuse misuse or negligent acts and power failure or surges fire flood accident actions of third parties or other events outside reasonable control Copyright Under the copyright laws this publication may not be reproduced or transmitted in any form electronic or mechanical including photocopying recording storing in an information retrieval system or translating in whole or in part without the prior written consent of National Instruments Corporation Trademarks NI DAQ is a trademark of National Instruments Corporation Product and company names listed are trademarks or trade names of their respective companies WARNING REGARDING MEDICAL AND CLINICAL USE OF NATIONAL INSTRUMENTS PRODUCTS National Instruments products are not designed with components and testing intended to ensure a level of reliability suitable for use in treatment and diagnosis of humans Applications of National Instruments products involving medical or clinical treatment can create a potential for accidental injury caused by product failure or by errors on the part of the user or application designer Any use or application of Nat
80. nal block is installed in position J4 Instead of using an external power source to supply power for your analog circuitry the DC to DC converter converts the 5 V digital power supply into 15 V and 15 V therefore supplying a convenient power source for your analog circuitry Warning If you accidentally short the terminals at J4 or otherwise connect the outputs from the DC to DC converter together damage to the converter and your breadboarded circuitry can occur Because of the power supply fuses F2 and F3 damage to your external digital power supply your expansion board or your computer is unlikely Regardless of how such connections might be incurred National Instruments is NOT liable for damage resulting from such connections Fuses and Power LED The 5 V line is protected by a 1 A fuse regardless of the S1 switch setting If you are using an external digital supply the digital ground line is also protected by a 1 A fuse In addition a diode is reverse biased across the external 5 V and digital ground inputs of J1 Warning If you connect your external digital power supply backwards the diode D1 conducts therefore limiting the voltage applied to the inputs to about 0 7 V In this case your power supply can go into thermal shutdown or blow a fuse but your breadboarded circuitry your expansion board and your computer should not be harmed National Instruments is NOT liable for damage resulting from such connections If you ar
81. nal conditioning boards are also being used with the same DAQ board for conditioning of the digital I O signals then an SC 205X Series cable adapter board is required Figure 1 1 shows the SC 2070 board mounted in a 19 in rack mount directly connected to the MIO 16 board SC 207X Series User Manual 1 2 National Instruments Corporation Chapter 1 Introduction Figure 1 1 SC 2070 Board Connected Directly to an MIO 16 Board The SC 207X Series boards can be mounted beside an SC 205X Series cable adapter board or an SC 206X Series signal conditioning board in a 19 in rack mount chassis You can mount your SC 207X Series board on the left or right side of the rack mount Figure 1 2 shows the SC 207X SC 206X and SC 205X Series boards connected to an MIO 16 board Figure 1 2 SC 207X Series Board SC 206X Series Board and SC 205X Series Board Connected to an MIO 16 Board National Instruments Corporation 1 3 SC 207X Series User Manual Introduction Chapter 1 What You Need to Get Started To set up and use your SC 207X board you will need the following m CI I Ld SC 2070 SC 2071 SC 2072 or SC 2072D board SC 207X Series User Manual 50 conductor NB1 0 5 or 1 0 m cable some kits do not contain either cable Your computer Optional Equipment You can use the following National Instruments products with your SC 207X Series board Type NBS ribbon cable 0 5 or 1 0 m Type NB10 cable Rack mount chassis kit with
82. nals can be used to connect digital power and ground inputs to an external power supply On the base model of the board the SC 2072 a second set of three terminals connects positive negative and common power inputs for powering onboard analog circuitry The second model of the board the SC 2072D comes equipped with a DC to DC converter that can be used to power analog circuitry see Power Connections later in this chapter A breadboard area of 2 4 by 4 6 in is also included The SC 2072 can be used in conjunction with the other signal conditioning accessories including the SC 206X Series boards and SSR Series boards An SC 205X Series cable adapter board must be used for connection of multiple signal conditioning accessories Figure 4 1 shows the parts locator diagram for the SC 2072 board Figure 4 2 shows the parts locator diagram for the SC 2072D board National Instruments Corporation 4 1 SC 207X Series User Manual SC 2072 Board Chapter 4 ojo O 2089 o o 0900 o o o o o o o o o o o o o o o o o o o o o o o o 820 O m mo SC 207e S N ASSY181310 0 REU R 9888888888988 INTERNAL PONER SELECTIONS 000000000000 S POSITIONS 00000000000 A 5V J2 PIN 49 GND J2 PIN 50 0000000000 F Ab Nie 000000000 000000000 P039 J2 PIN 00000000 GND J2 PIN 00000000
83. nded measurements 2 23 example 2 23 to 2 24 sources of error 2 24 working with thermocouples 2 17 SC 2071 board analog input 3 2 to 3 3 component positions in each channel table 3 3 onboard equivalent circuit figure 3 3 applications 3 7 to 3 14 attenuators voltage dividers building 3 12 to 3 14 connecting floating signal sources 3 8 connecting ground referenced signal sources 3 8 highpass filters building 3 10 to 3 12 lowpass filters building 3 8 to 3 10 soldering and desoldering 3 7 National Instruments Corporation Index board to board cabling 35 to 3 7 connecting to incompatible boards warning 3 7 connection using SC 2053 cable adapter board figure 3 6 daisy chaining Lab 1200 devices to BNC 2080 figure 3 6 DAQ devices used with SC 2071 table 3 5 direct connection to Lab 1200 devices figure 3 5 DAQ devices supported table 1 2 digital and timing signals 3 5 features 3 1 fuse and power LED 3 4 installation 5 1 to 5 2 mounting 3 7 overview 3 1 parts locator diagram 3 2 screw terminal connections 5 8 shield ground 3 4 temperature sensor 3 4 W1 jumper settings figure 3 4 thermocouple measurements 3 15 to 3 21 expected accuracies 3 20 to 3 21 input filtering and broken thermocouple detection 3 15 to 3 16 illustration 3 16 linearizing the data 3 17 to 3 18 National Bureau of Standards NBS polynomial coefficients table 3 18 measurement connections 3 18
84. ns acronyms metric prefixes and symbols are listed in the Glossary Related Documentation The following National Instruments documents contain information that you may find helpful as you read this manual Your DAQ hardware manuals e BNC 206X Series User Manual e SC 205X User Manual SC 207X Series User Manual x National Instruments Corporation About This Manual e SC 206X User Manual e National Instruments Application Note 043 Measuring Temperature with Thermocouples NIST Monograph 175 Temperature Electromotive Force Reference Functions and Tables for the Letter Designated Thermocouple Types Based on the ITS 90 National Institute of Standards and Technology Gaithersburg MD 20899 Customer Communication National Instruments wants to receive your comments on our products and manuals We are interested in the applications you develop with our products and we want to help if you have problems with them To make it easy for you to contact us this manual contains comment and configuration forms for you to complete These forms are in Appendix B Customer Communication at the end of this manual National Instruments Corporation xiii SC 207X Series User Manual Chapter 1 Introduction About the SC 207X Series Boards This chapter describes the SC 207X Series boards lists what you need to get started describes the optional equipment and software and explains how to unpack your SC 207X Series board
85. nto this category Differential Inputs If the MIO 16 board is configured for differential inputs ground referenced signal sources connected to the SC 2070 board need no special components added to the SC 2070 board The SC 2070 board inputs can be left in the factory original condition only with jumpers in the two series positions E and F see Table 2 1 Signal conditioning circuitry such as filters and attenuators described in Building Lowpass Filters Building Highpass Filters and Building Attenuators later in this chapter can be built in the open component positions Single Ended Inputs When measuring ground referenced signals the external signal supplies its own reference ground point and the MIO 16 should not supply one Therefore configure the MIO 16 board for nonreferenced single ended input mode In this configuration all of the signal grounds should be tied to AISENSE which connects to the negative input of the instrumentation amplifier on the MIO 16 board The SC 2070 board inputs can be left in the factory original condition with jumpers in the series position E or F depending on the channel Do not use the open positions that connect the input to AIGND B and D see Table 2 1 and Figure 2 2 in this configuration Therefore signal conditioning circuitry requiring a ground reference should not be built in the open component positions but must be built in the custom breadboard area using AISENSE as the ground reference Re
86. onductor Cable Digital I O SC 2051 or SC 206X Series 26 Conductor Cable 8 channel SSR Figure 4 4 Connection between a DIO 24 Board and the SC 2072 Board via the SC 2051 Board Warning Do not connect the SC 2072 board to any board other than a National Instruments DAQ device or a National Instruments SC 205X Series cable adapter board The SC 2072 board is not compatible with any other DAQ devices or cable adapter boards Attempts to use the SC 2072 board with products for which it is not intended can result in damage to the SC 2072 board the DAQ device or the host computer National Instruments is NOT liable for damages resulting from these connections The SC 2072 board uses a 50 pin ribbon cable connector to connect to the 50 pin I O connector on either a DAQ device or an SC 205X Series cable adapter board If the SC 205X Series cable adapter board is being used the SC 2050 connects to the DAQ device with a 50 conductor ribbon cable The SC 2072 board then connects to the other 50 pin I O connector on the SC 205X Series board For more information see Chapter 5 nstallation and Connections SC 207X Series User Manual 4 6 National Instruments Corporation Chapter 4 SC 2072 Board Mounting The SC 2072 board is equipped with metal standoffs so the board can be placed on a workbench near the host computer You can use an optional rack mount chassis which can be fitted with a flat a
87. out degradation Semiconductor sensors the easiest to use usually cannot be used above 70 C Thermocouples are inexpensive and physically small a feature that enables them to track temperature changes rapidly Thermocouple output voltages are very low on the order of 50 uV C The temperature coefficient changes with temperature resulting in a nonlinear curve The temperature can be determined from tables available from thermocouple vendors or calculated from polynomial equations such as those given in the next section SC 207X Series User Manual 3 14 National Instruments Corporation Chapter 3 SC 2071 Board Using the SC 2071 Board for Thermocouple Measurements The maximum voltage level generated by thermocouples is typically a few millivolts Therefore a Lab NB or Lab PC with a gain of 100 the highest possible should be used for best resolution Cold junction compensation with the SC 2071 board is accurate only if the temperature sensor reading is close to the actual temperature of the screw terminals Therefore when thermocouples are being read keep the SC 2071 board away from drafts or other temperature gradients such as those caused by heaters radiators fans and warm equipment Input Filtering and Broken Thermocouple Detection Optional To reduce noise you can connect a lowpass filter Refer to Building Lowpass Filters earlier in this chapter for an explanation of how to design these filters Broken thermocouple detec
88. panel such as the SC 2071 board Additional dissimilar junctions are formed where these wires contact the screw terminals Each of these junctions generates its own temperature dependent voltage Other temperature dependent voltages are generated at ribbon cable junctions and solder joints However the effects of these junctions are negligible and tend to cancel in most cases The voltage measured by the DAQ device is the sum of the voltages of all dissimilar metal junctions in the circuit not just the thermocouple junction used to measure temperature Only the temperature of the screw terminal junctions must be known to compensate for all dissimilar metal junctions in a system with constant temperature Thermocouple Law of Intermediate Metals Therefore if you know the temperature at the screw terminals you can easily calculate the temperature at the point of interest from the voltage measured A National Semiconductor LM 35CZ is used on the SC 2071 board to determine the temperature of the screw terminals The dissimilar metal junctions at the screw terminals are also referred to as the cold junction and the process of using the known temperature at that point to find the temperature at the unknown point is called cold junction compensation CJC Thermocouples are usually more desirable than direct reading sensors for several reasons Thermocouples are more rugged than most other sensors and can tolerate several hundred degree temperatures with
89. pecifications A 1 analog input channel configurations SC 2070 board 2 7 See alsosignal source connections applications See specific SC 207X board attenuators building SC 2070 board 2 15 to 2 16 example 2 16 illustration 2 16 input voltages greater than 42 V warning 2 15 three resistor circuit formula 2 15 SC 2071 board 3 12 to 3 14 example 3 14 illustration 3 13 input voltages greater than 42 V warning 3 12 two resistor circuit formula 3 13 B BNC 2081 Analog Breakout Board installing 5 3 board to board cabling SC 2070 board 2 5 to 2 6 SC 2071 board 3 5 to 3 7 SC 2072 board 4 6 National Instruments Corporation breadboarding area specifications A 1 broken thermocouple detection SC 2070 board 2 18 to 2 19 thermocouple circuit with open themocouple detect figure 2 19 SC 2071 board 3 15 to 3 16 thermocouple circuit with open themocouple detect figure 3 16 C cabling See board to board cabling channel configurations SC 2070 board 2 7 See also signal source connections differential DIFF input 2 7 nonreferenced single ended NRSE input 2 7 referenced single ended input RSE 2 7 cold junction 2 17 3 14 cold junction compensation CJC definition 2 17 3 14 SC 2070 board 2 17 SC 2071 board 3 15 cold junction temperature sensor specifications A 1 customer communication xiii B 1 D DAQ devices connection to SC 207X Series boards 1 2 illustrations 1 3 5 7
90. ple type To speed computation time a polynomial should be computed in nested form Consider the fourth order polynomial T ao ayx aox ay a4x Formula 2 5 If this polynomial is evaluated as it is written several unnecessary multiplications are performed to raise x to the various powers On the other hand if the polynomial is written and evaluated as follows then no powers are computed and execution proceeds much faster T ag x a x a2 x a3 xa4 Formula 2 6 Table 2 4 lists the National Bureau of Standards NBS polynomial coefficients for several popular thermocouples National Instruments Corporation 2 19 SC 207X Series User Manual SC 2070 Board Chapter 2 Table 2 4 NBS Polynomial Coefficients Temp 100 to 1 000 C 0 to760 C 0 t01 370 C 0 to1 000 C 0 to1 750 C 160 to 400 C Range 0 5 C 0 1 C 0 7 C 0 5 C 1 C 0 5 C ES EE M Dep EEE D EEE D NN RN The accuracies shown apply only to the polynomial and do not take into consideration errors introduced by the SC 2070 board the MIO 16 board or the thermocouple itself These polynomials are accurate only within the temperature ranges specified Also all terms must be included to achieve the specified accuracy To avoid the long computation time required for these high order polynomials the operating range of a thermocouple can be subdivided into several smaller ranges Each of the smaller ranges can
91. ples Assume that you are measuring the temperature of a high pressure boiler system using a PC XT computer a Lab PC an SC 2071 board and a J type thermocouple The maximum temperature that can be reached in this example is 300 C Before taking readings you must conFigure the Lab PC board for the maximum resolution possible A thermocouple Table shows that the output voltage never exceeds 16 to 17 mV recall that the exact voltage measured is a function of the SC 2071 board temperature as well as the temperature being measured Therefore you should select a 5 V input range with a gain of 100 450 mV maximum signal Set the jumpers on the Lab PC board for 5 V input range Set Jumper W1 on the SC 2071 board to select the temperature sensor as shown in Figure 3 4 To connect the thermocouple to channel 1 connect one lead to the CH1 terminal and the other to the AIGND terminal For this example do not add any lowpass filters or broken thermocouple detection The procedure for this example is as follows 1 Read the voltage from the temperature sensor If you are using an NI DAQ software package you can use the AT Read and AI Scale functions to do the reading The temperature sensor voltage is the voltage on channel 0 This voltage is 10 mV C so the gain should be either 1 or 10 for this reading 10 for the best resolution Multiply the voltage by 100 to get the SC 2071 board temperature in degrees Celsius For example if the reading is 0
92. poration Chapter 5 Installation and Connections External Power Connection If Necessary Because your SC 207X Series board draws very little current from the computer power supply an external 5 VDC supply is unnecessary in most cases If several high current SC 206X Series digital signal conditioning boards such as the SC 2062 board are being used on the same DAQ device as the SC 207X Series board some of these boards need to be powered by an external 5 VDC supply Because the SC 206X Series boards draw much more current than the SC 207X Series the SC 206X Series boards should be powered from the external supply and the SC 207X Series board should be run from the host computer power supply However your SC 207X Series board can be powered from an external 5 VDC power supply An external supply can be necessary in the following situations A particularly high current circuit has been constructed on the general purpose breadboarding area The power requirements for equipment connected to the computer s power supply exceed the rating for that supply To connect the external power supply the power supply must be turned off to the SC 2070 or the SC 2071 first remove fuse F1 Then connect the wires from the 5 VDC and the supply ground lines to the screw terminals labeled 5 V and DGND on the board To connect the external digital power supply the power supply must be turned off to the SC 2072 connect the wires from the 5 VDC an
93. pose board it has a more flexible power connection scheme than the SC 2070 and SC 2071 boards In addition the SC 2072 board comes in two different configurations based on your external power supply needs Both configurations of the SC 2072 come with two power selection switches and a three position screw terminal block all of which are dedicated to selecting the digital power supply and its ground Switch S1 selects either the internal or the external digital power supply If you set the switch to the external supply labeled EXT the terminal block is connected to the local power and ground lines If you set the switch to the internal supply labeled INT the switch S2 is responsible for selecting the power inputs from the I O cable Switch S2 is a three position switch that configures the SC 2072 to connect to pins 49 5 V and 50 DGND in position A to no I O pins in position B and to pins 33 DGND and 34 5 V in position C Table 4 1 shows the setting to be used with each of the National Instruments DAQ devices SC 207X Series Table 4 1 Switch S2 Settings for National Instruments DAQ Devices AT DIO 32F AT MIO 16 AT MIO 16D AT MIO 16F 5 AT MIO 16X AT MIO 64F 5 Lab PC Lab PC DAQCard 1200 DAQPad 1200 PCI 1200 PC DIO 24 PC DIO 96 PC LPM 16 PC TIO 10 MC DIO 24 MC DIO 32F MC MIO 16 Lab LC Lab NB NB DIO 24 NB DIO 32F NB MIO 16 NB MIO 16X DAQCard 700 DAQCard DIO 24 PC OPDIO 16 xijnnaw iInw n
94. pping costs of returning to the owner parts which are covered by warranty National Instruments believes that the information in this manual is accurate The document has been carefully reviewed for technical accuracy In the event that technical or typographical errors exist National Instruments reserves the right to make changes to subsequent editions of this document without prior notice to holders of this edition The reader should consult National Instruments if errors are suspected In no event shall National Instruments be liable for any damages arising out of or related to this document or the information contained in it EXCEPT AS SPECIFIED HEREIN NATIONAL INSTRUMENTS MAKES NO WARRANTIES EXPRESS OR IMPLIED AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE CUSTOMER S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER NATIONAL INSTRUMENTS WILL NOT BE LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA PROFITS USE OF PRODUCTS OR INCIDENTAL OR CONSEQUENTIAL DAMAGES EVEN IF ADVISED OF THE POSSIBILITY THEREOF This limitation of the liability of National Instruments will apply regardless of the form of action whether in contract or tort including negligence Any action against National Instrument must be brought within one year after the cause of action accrues National Instruments shall not be liab
95. s Soldering and Desoldering on the SC 2071 Board With the applications discussed here you must modify the printed circuit board usually in the form of removing jumpers and adding components The SC 2071 board is shipped with one jumper in the C position see Table 3 1 and Figure 3 2 Use a low wattage soldering iron 20 to 30 W when soldering to the board To desolder on the SC 2071 vacuum type tools work best Use care when desoldering to avoid damaging component pads Only use rosin core electronic grade solder Acid core solder damages the printed circuit board and components National Instruments Corporation 3 7 SC 207X Series User Manual SC 2071 Board Chapter 3 Connecting Floating Signal Sources A floating signal source is a signal source that is not connected in any way to the building ground system but has an isolated ground reference point If an instrument or device has an isolated output that instrument or device falls into the floating signal source category Some examples of floating signal sources are outputs for the following thermocouples transformers battery powered devices optical isolators and isolation amplifiers The ground reference of a floating source must be tied to the ground of the DAQ device No special components are needed to measure signals from floating sources connected to the SC 2071 board Because the negative side of the single ended inputs is grounded all floating sources are referenced to
96. s 2 6 to 2 16 attenuators voltage dividers building 2 15 to 2 16 channel configurations 2 7 connecting ground referenced signal sources 2 9 differential inputs 2 9 single ended inputs 2 9 connecting nonreferenced or floating signal sources 2 7 to 2 8 differential inputs 2 7 to 2 8 single ended inputs 2 8 highpass filters building 2 13 to 2 14 lowpass filters building lowpass filters 2 10 to 2 11 soldering and desoldering 2 7 board to board cabling 2 5 to 2 6 connecting to incompatible boards warning 2 6 connection using SC 2050 cable adapter board figure 2 6 DAQ devices used with SC 2070 table 2 5 direct connection to MIO 16 board figure 2 5 DAQ devices supported table 1 2 National Instruments Corporation digital and timing signals 2 4 to 2 5 features 2 1 fuse and power LED 2 4 installation 5 1 to 5 2 mounting 2 6 overview 2 1 parts locator diagram 2 2 screw terminal connections 5 8 shield ground 2 4 temperature sensor 2 3 to 2 4 W1 jumper settings figure 2 4 thermocouple measurements 2 17 to 2 25 differential measurements 2 22 example 2 22 to 2 23 expected accuracies 2 25 input filtering and broken thermocouple detection 2 18 to 2 19 illustration 2 19 linearizing the data 2 20 to 2 21 National Bureau of Standards NBS polynomial coefficients table 2 21 selecting gain and input ranges 2 19 to 2 20 thermocouple voltage output extremes figure 2 20 single e
97. s illustrating signal conditioning with single ended inputs refer to Applications later in this chapter National Instruments Corporation 3 2 SC 207X Series User Manual Chapter 3 SC 2071 Board 4 Channel 92 Jumper Installed Here at Factory To Input Multiplexer O a C gt AIGND Figure 3 2 Onboard Equivalent Circuit The components are numbered differently for each channel Table 3 1 is a list of the components in each channel and their correspondence to the circuit shown in Figure 3 2 Table 3 1 Component Positions in Each Channel Position in Figure 3 2 Channel A B C D 0 When the board is shipped a jumper is inserted in the C position of the input network You can easily remove the jumper to build analog input signal conditioning circuits A few specific applications showing the use of these open component positions are discussed in Applications later in this chapter National Instruments Corporation 3 3 SC 207X Series User Manual SC 2071 Board Chapter 3 Temperature Sensor The SC 2071 board is equipped with an onboard temperature sensor for use with thermocouple cold junction compensation This sensor a National Semiconductor LM 35CZ generates a voltage output of 10 mV C with an accuracy of 1 C The sensor is jumper enabled on input channel 0 Jumper W1 is used to choose either the temperature sensor or the external screw terminals as the input source for channel 0
98. s relatively unimportant a few megohms or more works fine With a high value resistor you can detect an open or defective thermocouple If the thermocouple opens the voltage measured across the input terminals rises to 5 V a value much larger than any legitimate thermocouple voltage The 100 kQ resistor between the negative input and AIGND is a bias current return path as described under Connecting Floating Signal Sources earlier in this chapter A sample circuit and component placement for a lowpass filter and broken thermocouple detection are shown in Figure 2 13 Assume the thermocouple is connected to channel 1 National Instruments Corporation 2 17 SC 207X Series User Manual SC 2070 Board Chapter 2 Component Positions Channel 9 in Channel 1 in 7 1 uF Capacitor 10 kQ Resistor 100 kQ Resistor Input Schematic E 10kQ Channel QD O AW O G To 1 uF Input Multiplexer Channel Q Figure 2 13 Thermocouple Circuit with Open Thermocouple Detect and Lowpass Noise Filter Selecting the Gain and Input Ranges Because thermocouple output voltages are very low a gain of 500 or 100 is usually necessary for best resolution The input range on the MIO 16 should be set to 5 V to improve resolution These settings can be used in all but a few cases such as a fairly high output thermocouple type that is being used at elevated temperatures Table 2
99. signal conditioning accessories you must use an SC 205X Series cable adapter board National Instruments Corporation 2 1 SC 207X Series User Manual SC 2070 Board Chapter 2 Figure 2 1 shows the parts locator diagram for the SC 2070 board AISENSE O00000000000000 000000000000000 000000000000000 O000000000000000 000000000000000 OOOOOOOOOOOOOOO 000000000000000 000000000000000 O000000000000000 000000000 00000 000000000000000 000000000000000 O00000000000000 000000000000000 000000000 00000 000000000000000 000000000000000 J11 sent ax PERENNEM O a B O ro Foje Loin O O O O00 R32 O Rz5 O R5 O FoOo nssi F O y OOR21 FOO4R 9 OO dR42 FOOdR40 O OO R3 LFoodni OO R33 C2 CA C7 O OO R48 Food n4e FO OOOOOOOOOOOOOOO 000000000000000 00000000000000 2 000000000000000 000000000000000 O00000000000000 000000000000000 000000000000000 000000000000000 NATIONAL INSTRUMENTS CORP ASSY180950 01 REU D S N SC 2070 COPYRIGHT 1991 Q OO Fe o s o O00000000000000 000000000000000 000000000000000 20000 0
100. sor figure 2 4 SC 2071 temperature sensor figure 3 4 W2 jumper SC 2070 shield ground figure 2 4 SC 2071 shield ground figure 3 4 L linearizing data for thermocouple output voltage National Bureau of Standards NBS polynomial coefficients table 2 21 3 18 SC 2070 board 2 20 SC 2071 board 3 17 to 3 18 lowpass filters connecting to SC 2070 board 2 18 thermocouple circuit with lowpass noise filter figure 2 19 National Instruments Corporation Index connecting to SC 2071 board 3 15 thermocouple circuit with lowpass noise filter figure 3 16 lowpass filters building SC 2070 board 2 10 to 2 11 lowpass filter on differential channel 1 figure 2 12 normalized frequency response figure 2 10 SC 2071 board 3 8 to 3 10 lowpass filter on channel 1 figure 3 10 normalized frequency response figure 3 9 M manual See documentation mounting rack mount chassis cover attachment 5 9 rack mounting 5 3 to 5 4 attaching mountable board to chassis figure 5 3 double height mounting figure 5 4 locations for SC 207X boards figure 5 3 SC 2070 board 2 6 SC 2071 board 3 7 SC 2072 board 4 7 N National Bureau of Standards NBS polynomial coefficients table 2 21 3 18 nonreferenced or floating signal sources 2 7 to 2 8 differential inputs 2 7 bias return resistor for DC coupled foating source on channel 1 figure 2 8 single ended inputs 2 8 nonreferenced single ended NR
101. stance required is preferable because more standard resistor values are available If a capacitance of 1 UF is available then the resistance is by substitution into Formula 3 1 39 789 Q or about 39 80 KO Therefore in this example the input has a 39 80 kQ resistor or closest standard value in its series position C The closest standard 5 tolerance resistor is 39 KQ For a lowpass filter on a single ended input 5 tolerance resistors suffice Figure 3 9 shows both the schematic and the component placement for a 4 Hz lowpass filter placed on channel 1 National Instruments Corporation 3 9 SC 207X Series User Manual SC 2071 Board Chapter 3 Component Positions R8 a1 uF cap R7 Channel 1 39 kQ Resistor Lj 1 uF Capacitor Input Schematic 39 kQ Channel 7 O AAA O C To Input Multiplexer gt AIGND Figure 3 9 Lowpass Filter on Channel 1 Building Highpass Filters You can easily install simple RC highpass filters in the SC 2071 board on any input channel The filters are useful for accurate high frequency measurement and low frequency noise rejection By substituting resistance and capacitance values into the following formula you can calculate a simple one pole RC filter to have a 3 dB point cutoff frequency 1 f OxRC Formula 3 2 The response rolls off at a rate of 20 dB per decade drop in frequency thereafter A Bode plot of the amplitude
102. t results use a well calibrated MIO 16 board so that offsets can be neglected Offset error can be eliminated however by grounding one channel on the SC 2070 board and measuring the voltage This value the offset of the MIO 16 can then be subtracted in software from all other readings Thermocouple wire error is the result of inconsistencies in the thermocouple manufacturing process These inconsistencies or nonhomogeneities are the result of defects or impurities in the thermocouple wire The errors vary widely depending on the thermocouple type and even the wire gauge used but a value of 2 C is typical For best results use an average of about 100 readings When using an average typical accuracies are about 2 C Thermocouple Measurement Accuracies Table 2 5 lists the expected thermocouple accuracies in degrees Celsius subject to the following conditions e The MIO 16 board is correctly calibrated e The temperature of the screw terminals equals the temperature of the board no gradients on the board The uncertainties listed apply at either 0 C Type J K E T or 600 C Type S R The linearization errors of the NBS polynomials in Table 2 4 measurement error of a calibrated MIO 16 and the 1 C cold junction sensor error are included Thermocouple wire error is neglected because of a dependence on the conditions listed previously Finally these uncertainties are for the gains listed with a 10 V input range
103. ternal Power Connection If Necessary 5 4 SC 207X Series Board Connection esee eene nennen esee nen 5 7 Signal Connections PC 5 8 Ribbon Cable Connectors nann a E a A S RE EE ENS 5 8 Screw Terminal Connections for the SC 2070 and the SC 2071 5 8 Screw Terminal Connections for the SC 2072 cceecccecccccccesssssseeecseseeeees 5 9 Rack Mount Chassis Cover Attachment see 5 9 Appendix A SPCCHICALIONS LAS eie nma eMe dee ias Me ue end ese us A 1 Appendix B Customer Communication rete trente enne B 1 GOSS ANY fos t tetto dant ae our tei uA cate fu an Coraes Glossary 1 Ile 5 uci Me IL T E Index 1 National Instruments Corporation vii SC 207X Series User Manual Contents Figure 1 1 Figure 1 2 Figure 2 1 Figure 2 2 Figure 2 3 Figure 2 4 Figure 2 5 Figure 2 6 Figure 2 7 Figure 2 8 Figure 2 9 Figure 2 10 Figure 2 11 Figure 2 12 Figure 2 13 Figure 3 1 Figure 3 2 Figure 3 3 Figure 3 4 Figure 3 5 Figure 3 6 Figure 3 7 Figure 3 8 Figure 3 9 Figure 3 10 Figure 3 11 Figure 3 12 Figure 3 13 Figure 4 1 Figure 4 2 Figure 4 3 Figure 4 4 Figure 5 1 Figure 5 2 Figure 5 3 Figure 5 4 SC 207X Series User Manual Viii Figures SC 2070 Board Connected Directly to an MIO 16 Board 1 3 SC 207X Series Board SC 206X Series Board and SC 205X Series Board Connect
104. the same ground The SC 2071 board inputs can be left in the factory original condition that is with a jumper in the series position C see Table 3 1 Signal conditioning circuitry such as the filters and attenuators described in Building Lowpass Filters Building Highpass Filters and Building Attenuators later in this chapter can be used Connecting Grounded Signal Sources A grounded signal source is connected in some way to the building system ground therefore the signal source is already connected to a common ground point with respect to the DAQ device assuming the host computer is plugged into the same power system Nonisolated outputs of instruments and devices that plug into the building power system fall into this category In the case of grounded signal sources connected to the single ended inputs of the SC 2071 board a small DC error can be measured because of differences between the ground potentials of the signal source and the Lab 1200 device This error is unavoidable with the SC 2071 board because the Lab 1200 device is configured only for ground referenced single ended inputs You need no special components to measure signals from grounded sources connected to the SC 2071 board The inputs of the SC 2071 board can be left in the factory original condition that is with only a jumper in the series position C see Table 3 1 and Figure 3 2 Signal conditioning circuitry such as the filters and attenuators described in Building
105. tion circuitry is built by connecting a high value resistor between the positive input and 5 V The value of this resistor is relatively unimportant a few megohms or above works fine With a high value resistor you can detect an open or defective thermocouple If the thermocouple opens the voltage measured across the input terminals rises to 5 V a value much larger than any legitimate thermocouple voltage A sample circuit and the component placement for a lowpass filter and broken thermocouple detection are shown in Figure 3 13 assuming that the thermocouple is connected to channel 1 National Instruments Corporation 3 15 SC 207X Series User Manual SC 2071 Board Chapter 3 Component Positions R8 a1 uF cap AIGND VY Channel 1 Y in R6 10 kQ ow j leg 10 MQ Resistor 1 uF Capacitor 10 kQ Resistor Input Schematic C 10kQ Channel VY O ANN To Input Multiplexer gt AIGND Figure 3 13 Thermocouple Circuit with Open Thermocouple Detect and Lowpass Noise Filter Selecting the Gain and Input Ranges Because thermocouple output voltages are very low a gain of 100 is usually necessary for best resolution The input range on the Lab 1200 device should usually be set to 5 V to improve resolution These settings can be used in all but a few cases such as a fairly high output thermocouple type used at elevated temperatures Table 3 3 lists the voltage ex
106. tions for channel 1 The gain G of this attenuator is given by the following formula Rp Ls Rc Rp Formula 3 3 Therefore the input to the Lab 1200 device V1 4p is VLab Vsc G where Vsc is the voltage applied to the screw terminals of the SC 2071 board The accuracy of this gain equation depends on the tolerances of the resistors used Component Positions R8 10kQ D AIGND Channel 1 R6 10kQ C 10 kQ Resistor Input Schematic Ro 10kQ Channel 7 O NN O C O D To Input Multiplexer O gt AIGND Figure 3 12 Attenuator for Use with SC 2071 Board Inputs National Instruments Corporation 3 13 SC 207X Series User Manual SC 2071 Board Chapter 3 Example Using the values in Figure 3 12 10 KQ 1 G 190kQ 10kQ 2 Therefore Vj ap 1 2 Vsc With the Lab 1200 device configured for 5 V inputs the device can acquire 10 V signals with this attenuator circuit Working with Thermocouples One of the most frequently used temperature transducers is the thermocouple A thermocouple is created whenever two dissimilar metals are brought in contact and the contact produces a small voltage as a function of temperature In most measurement situations a thermocouple is placed where the temperature is to be measured then two wires consisting of the same type of metal as each side of the thermocouple are run back to a termination
107. to your software or hardware and use the completed copy of this form as a reference for your current configuration Completing this form accurately before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently If you are using any National Instruments hardware or software products related to this problem include the configuration forms from their user manuals Include additional pages if necessary Name Company Address Fax Phone Computer brand Model Processor Operating system Speed MHz RAM MB Display adapter Mouse yes no Other adapters installed Hard disk capacity MB Brand Instruments used National Instruments hardware product model Revision Configuration National Instruments software product Version Configuration The problem is List any error messages The following steps will reproduce the problem Documentation Comment Form National Instruments encourages you to comment on the documentation supplied with our products This information helps us provide quality products to meet your needs Title SC 207X Series User Manual Edition Date November 1995 Part Number 371173A 01 Please comment on the completeness clarity and organization of the manual If you find errors in the manual please record the p
108. tremes from several popular thermocouple types Use this Table as a guide for determining the best gain and input range settings to use If the thermocouples are being used in a known temperature range consult a book of thermocouple tables to determine the approximate millivolt output and the best gain and input range settings SC 207X Series User Manual 3 16 National Instruments Corporation Chapter 3 SC 2071 Board Table 3 3 Thermocouple Voltage Output Extremes mV Thermocouple 8 096 at 210 C 42 922 at 760 C 6 548 at 270 C 54 807 at 1370 C 9 835 at 270 C 76 358 at 1000 C 6 258 at 270 C 20 869 at 400 C 0 000 at 0 C 18 612 at 1760 C 0 000 at 0 C 21 006 at 1760 C 0 003 at 20 C 13 814 at 1820 C Source of information is Omega Temperature Measurement Handbook amp Encyclopedia Omega Engineering Stamford CT All temperatures are the difference between the measuring end and the cold junction or SC 2071 board screw terminals in this case Linearizing the Data Thermocouple output voltages are highly nonlinear The Seebeck coefficient or voltage change per degree of temperature change can vary by a factor of three or more over the operating temperature range of some thermocouples For this reason the temperature from thermocouple voltages must either be approximated by polynomials or matched against a look up table The polynomial approach is easier to use but it trades measurement time for
109. ts attenuators must be built on the custom breadboard area Attenuators can be used to reduce a signal that is outside the normal input range of the DAQ board 10 V maximum Warning The SC 2070 board is not designed for any input voltages greater than 42 V even if a user installed voltage divider reduces the voltage to within the input range of the DAQ board Input voltages greater than 42 V can result in damage to the SC 2070 board any and all boards connected to it and the host computer Overvoltage can also cause an electric shock hazard for the operator National Instruments is NOT liable for damage or injury resulting from such misuse A three resistor circuit for attenuating voltages at the differential inputs of the SC 2070 board is shown in Figure 2 12 The figure also shows the placement of the resistors on the open component positions for differential channel 1 The gain G of this attenuator is given by the following formula RG G RE Re RO Formula 2 3 Therefore the input to the MIO 16 board Vyro is Vmio Vsc G where Vsc is the voltage applied to the screw terminals of the SC 2070 The accuracy of this gain equation depends on the tolerances of the resistors used SC 207X Series User Manual 2 14 National Instruments Corporation Chapter 2 SC 2070 Board Component Positions R12 10kQ F tw QC uk ai in Channel 1 A R11 in C3 a 10 kO resistor G ER 10 kQ
110. versus normalized frequency is shown in Figure 3 10 SC 207X Series User Manual 3 10 National Instruments Corporation Chapter 3 SC 2071 Board Amplitude 1 0 1 0 01 0 0001 0 001 0 01 Normalized Frequency Figure 3 10 Normalized Frequency Response of Highpass Filter When measuring high frequency signals about 20 kHz if you have 20 Hz noise on your inputs you can add a highpass filter with a cutoff frequency of 20 KHz The 20 Hz noise then attenuates by 60 dB Notice that your 20 kHz signal also attenuates but by only 3 dB Do not neglect any potential attenuation of signals of interest by this low order filter You must also choose the filter component values The resistance or the capacitance can be selected arbitrarily one value determines the other Picking the capacitor first and letting its value determine the resistance required is preferable because more standard resistor values are available If a 0 001 uF capacitor is available the resistance is by substitution into Formula 3 2 77958 Q or about 8 0 kQ Therefore in this example the input channel has a 7 96 kQ resistor or closest standard value in position D and a 0 001 uF capacitor in position C The closest standard 5 tolerance resistor is 8 2 kQ Resistor tolerance is not a concern in this application because most capacitors have poor tolerances for example 20 to 30 Figure 3 11 shows both the schematic and the component placement

SC-207X Series User Manual

Contents

Download Pdf Manuals

Related Search

Related Contents