SCXI-1521

SCXI Quarter-Bridge Strain Gage Input Module NI SCXI-1521, NI SCXI-1521B • 24 quarter-bridge strain gage • 350 Ω (SCXI-1521) • 120 Ω (SCXI-1521B) • Programmable excitation (0 to 5 V) per channel • Programmable shunt and null calibration per channel • 10 Hz filter per channel • Onboard quarter-bridge completion and shunt calibration resistors • NI-DAQmx 7.3 simplifies configuration and measurements inputs1 NEW Operating Systems • Windows 2000/NT/XP Recommended Software • LabVIEW • LabWindows/CVI • Measurement Studio Other Compatible Software • Visual Basic, C, C++ Measurement Services Software (included) • NI-DAQmx 7.3 Calibration Certificate Included 1For half-bridge or full-bridge strain gage measurements, please consider the SCXI-1520. Overview The National Instruments SCXI-1521 and SCXI-1521B are quarterbridge strain gage input modules that offer all of the features you need for high-channel-count applications. Each NI SCXI-1521/B is shipped with a NIST-traceable calibration certificate. Each SCXI-1521/B module can multiplex its signals into a single channel of the controlling DAQ device, and you can add more modules to increase channel count. Null Compensation Each input channel of an SCXI-1521/B includes a circuit to remove bridge offset voltage. Driver software nulls the offset voltage to zero in seconds. You do not need to manually adjust a potentiometer. By removing this offset through the measurement hardware, you can achieve better measurement resolution. Shunt Calibration Each input channel of an SCXI-1521/B includes an accurate and stable shunt calibration resistor with which you can progamatically simulate loading effects on your strain gage to compensate for strain gage errors. The shunt calibration resistors located inside of the module. You enable or disable the shunt resistors through software commands. Analog Input Each of the 24 analog inputs of the SCXI-1521/B consists of a quarter-bridge completion resistor (350 Ω for the SCXI-1521 and 120 Ω for the SCXI-1521B), and a 10 Hz, 2-pole Butterworth filter. You can program the excitation over 1024 different levels from 0 to 5 V. The 2-pole Butterworth filters provides lowpass filtering to block noise and ensure measurement accuracy. Measurement Services Software NI-DAQmx is the robust measurement services software included with all National Instruments data acquisition and signal conditioning products. This easy-to-use software tightly integrates the full functionality of your DAQ hardware to LabVIEW, LabWindows/CVI, and Measurement Studio for Visual Basic. High-performance features include multidevice synchronization, networked measurements, and DMA data management. Bundled with NI-DAQmx, the Measurement & Automation Explorer (MAX) utility simplifies the configuration of your measurement hardware with device test panels, interactive measurements, and scaled I/O channels. NI-DAQmx also provides numerous example programs for LabVIEW and other application development environments to get you started with your application quickly. Special Functions – Part Number 777687-17 Calibration The SCXI-1521/B modules provide simple yet powerful calibration capabilities. Each module has an onboard calibration EEPROM that stores calibration constants for each channel; factory calibration constants are stored in a protected area of the EEPROM. NI-DAQ traditional and NI-DAQmx transparently use the calibration constants to correct for gain and offset errors for each channel. Terminal Block SCXI-1317 Type Screw terminals CJ Sensor – Compatible Modules SCXI-1521 & SCXI-1521B Front-mounting Cabling – Table 1. Terminal Block Options for the SCXI-1521/B SCXI Quarter-Bridge Strain Gage Input Module Ordering Information NI SCXI-1521 ................................................................777966-21 NI SCXI-1521B ..........................................................777966-21B Includes NI-DAQmx software. For more information on extended warranty and value-added services, visit ni.com/services BUY ONLINE! Visit ni.com/info Specifications This appendix lists the specifications for the SCXI-1521/B modules. These specifications are typical at 25 °C unless otherwise noted. Bridge Completion SCXI-1521......................................................... Long term stability ........................................... SCXI-1521B....................................................... Long term stability ........................................... Analog Input Number of channels......................................... Voltage gain ..................................................... Input coupling................................................... Overvoltage protection..................................... Inputs protected ............................................... 24 42 DC ±11 V powered on and off 350 Ω, 0.1%, 2 ppm/°C max, 55mW @ °50 C 0.02%/yr 120 Ω, 0.1%, 2 ppm/°C max, 55mW @ °50 C 0.02%/yr Shunt Calibration Type .................................................................. Shunt across quarter-bridge completion resistor Shunt resistor ................................................... Fixed 100 kΩ, 0.1%, 10 ppm/°C , 150mW Switch resistance............................................. 15 Ω max 7.5 Ω typ Transfer Nonlinearity...................................................... Gain error After calibration1 ....................................... Before calibration2..................................... Input offset error .............................................. 1This 0.02% max 0.1% of reading max 4.0% of reading max 7 mV max 1 mV typ Power Requirements (from SCXI Backplane) V+...................................................................... 18.5 to 25 VDC, +170 mA min V........................................................................ 18.5 to –25 VDC, –170 mA min +5 V .................................................................. +4.75 to 5.25 VDC, 50 mA min is the error after software correction. Gain error is taken into account in the software correction coefficients stored in the onboard EEPROM. These constants are applied automatically when using LabVIEW or NI-DAQmx. 2This is the error before software calibration. Physical Dimensions....................................................... 3.0 by 17.2 by 20.3 cm (1.2 by 6.9 by 8.0 in.) Maximum Working Voltage Maximum working voltage refers to the signal voltage plus the common-mode voltage. Channel-to-earth .............................................. Input should remain within ±11 V of ground. Installation Category I Channel-to-channel .......................................... Input should remain within ±11 V of ground. Installation Category I Dynamic Minimum scan interval (per channel, any gain in multiplexed mode) ±0.012% accuracy ............................................ 3 µs ±0.006% accuracy ............................................ 10 µs ±0.0015% accuracy .......................................... 20 µs Noise RTI1 0.1 to 10 Hz ...................................................... 2.5 µVpp > 10 Hz.............................................................. 1 µVrms in 1MHz bandwidth 1Includes Environmental Operating temperature..................................... Storage temperature ........................................ Humidity ........................................................... Maximum altitude ............................................ Pollution Degree (indoor use only)................... 0 to 50 °C 20 to 70 °C 10 to 90% RH, noncondensing 2,000 m 2 excitation voltage noise contribution Filter Lowpass filter type........................................... 2-pole Butterworth (12 dB/octave rolloff) 3 dB bandwidth ................................................ 10 Hz Safety The SCXI-1521/B is designed to meet the requirements of the following standards of safety for electrical equipment for measurement, control, and laboratory use: • IEC 61010-1, EN 61010-1 • UL 61010-1 • CAN/CSA-C22.2 No 61010-1 For UL and other safety certifications, refer to the product label, or visit ni.com/certification, search by model number or product line, and click the appropriate link in the Certification column. Stability Recommended warm-up time.......................... 30 minutes Gain drift .......................................................... ±11 ppm /°C max ±4 ppm /°C typ Offset drift ........................................................ ±3 µV /°C max ±1 µV /°C typ Offset Null Compensation Range................................................................ ±0.45% of excitation voltage Resolutioin........................................................ 4,096 counts of resolution (±9,000 me offset null compensation range, 4.4 me resolution for GF = 2.0) Electromagnetic Compatibility EmissionsEN 55011 Class A at 10 m FCC Part 15A above 1 GHz Immunity ..EN 61326:1997 + A2:2001, Table 1 EMC/EMICE, C-Tick, and FCC Part 15 (Class A) Compliant Note: For EMC compliance, operate this device with shielded cabling. Excitation Type .................................................................. Settings ............................................................ Error .................................................................. Maximum output current ................................. Load regulation (open to 240 W) ..................... Temperature drift.............................................. Protection ......................................................... Constant voltage 0.0 to 5.0 V in 1023 steps ±20 mV ±0.3% max 21 mA 0.08% ±10ppm/°C ±30 µV/°C max Surge arrestors in parallel with excitation terminals, shunt to ground, short circuit protected CE Compliance The SCXI-1521/B meets the essential requirements of applicable European Directives, as amended for CE marking, as follows: Low-Voltage Directive (safety)......................... 73/23/EEC Electromagnetic Compatibility Directive (EMC) ................................................ 89/336/EEC Note: Refer to the Declaration of Conformity (DoC) for this product for any additional regulatory compliance information. To obtain the DoC for this product, visit ni.com/certification, search by model number or product line, and click the appropriate link in the Certification column. 2 National Instruments • Tel: (800) 433-3488 • Fax: (512) 683-9300 • info@ni.com • ni.com NI Services and Support NI has the services and support to meet your needs around the globe and through the application life cycle – from planning and development through deployment and ongoing maintenance. We offer services and service levels to meet customer requirements in research, design, validation, and manufacturing. Visit ni.com/services. Local Sales and Technical Support In offices worldwide, our staff is local to the country, giving you access to engineers who speak your language. NI delivers industryleading technical support through online knowledge bases, our applications engineers, and access to 14,000 measurement and automation professionals within NI Developer Exchange forums. 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