Appendix A
Specifications
©
National Instruments Corporation
A-3
Drift ........................................................ 40 ppm/°C
Lead resistance effect............................. Negligible (4-wire measurement)
Resistance range..................................... 10 k
Ω
, maximum
Strain Gauge Mode
Bridge types ........................................... Quarter-, half-, and full-bridge
Bridge completion.................................. Two 4.5 k
Ω
±0.05% ratio
tolerance resistors
Excitation voltage
1
................................. 3.333 V ±0.04% or 10 V ±0.2%
Resistance range..................................... 120
Ω
, minimum at 3.333 V
800
Ω
, minimum at 10 V
Half-bridge voltage ................................ V
EXT
/2 ±0.04%
Cold-Junction Sensor
2
SCXI-1320 and SCXI-1321
Accuracy ......................................... 1.0 °C over 0 to 55 °C
Output ............................................. 10 mV/°C
SCXI-1328
Accuracy
3
....................................... 0.35 ° from 15 to 35 °C
0.65 ° from 0 to 15 ° and
35 to 55 °C
Output ............................................. 1.91 to 0.58 V from 0 to 55 °C
Output at 25 °C ............................... 1.25 V
Note
You can find the temperature T (°C) as follows:
T
=
T
K
– 273.15
1
NI calibrates the excitation voltage by using a 120
Ω
load resistor that is connected to the excitation voltage output through
the SCXI-1320 terminal block. The excitation voltage values are measured at the output screw terminals of the SCXI-1320
terminal block. Because of the voltage drop in various portions of the circuit, the actual excitation voltage might vary slightly
with the resistance of the cable and of the load.
2
Located on the SCXI-1320, SCXI-1328, and SCXI-1321 terminal blocks.
3
Includes the combined effects of the temperature sensor accuracy and the temperature difference between the temperature
sensor and any screw terminal.