SCXI-1521 Datasheet, PDF (2/3 Pages) National Instruments Corporation – 24 quarter-bridge strain gage inputs/Programmable excitation

SCXI Quarter-Bridge Strain Gage Input Module
Ordering Information
NI SCXI-1521 ................................................................777966-21
NI SCXI-1521B ..........................................................777966-21B
Includes NI-DAQmx software.
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Specifications
This appendix lists the specifications for the SCXI-1521/B modules. These specifications are typical at
25 °C unless otherwise noted.
Analog Input
Number of channels......................................... 24
Voltage gain ..................................................... 42
Input coupling................................................... DC
Overvoltage protection..................................... ±11 V powered on and off
Inputs protected ............................................... <AI0..23>
Transfer
Nonlinearity...................................................... 0.02% max
Gain error
After calibration¹ ....................................... 0.1% of reading max
Before calibration²..................................... 4.0% of reading max
Input offset error .............................................. 7 mV max
1 mV typ
1_{This 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.
2_{This is the error before software calibration.}
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 µV_rms in 1MHz bandwidth
1_{Includes excitation voltage noise contribution}
Filter
Lowpass filter type........................................... 2-pole Butterworth (12 dB/octave rolloff)
3 dB bandwidth ................................................ 10 Hz
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)
Excitation
Type .................................................................. Constant voltage
Settings ............................................................ 0.0 to 5.0 V in 1023 steps
Error .................................................................. ±20 mV ±0.3% max
Maximum output current ................................. 21 mA
Load regulation (open to 240 W) ..................... 0.08%
Temperature drift.............................................. ±10ppm/°C ±30 µV/°C max
Protection ......................................................... Surge arrestors in parallel with excitation terminals,
shunt to ground, short circuit protected
Bridge Completion
SCXI-1521......................................................... 350 Ω, 0.1%, 2 ppm/°C max, 55mW @ °50 C
Long term stability ........................................... 0.02%/yr
SCXI-1521B....................................................... 120 Ω, 0.1%, 2 ppm/°C max, 55mW @ °50 C
Long term stability ........................................... 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
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
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
Environmental
Operating temperature..................................... 0 to 50 °C
Storage temperature ........................................ 20 to 70 °C
Humidity ........................................................... 10 to 90% RH, noncondensing
Maximum altitude ............................................ 2,000 m
Pollution Degree (indoor use only)................... 2
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.
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.
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.
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