National Instruments 9211 Computer Drive User Manual


 
USB-9211/9211A User Guide and Specifications 14 ni.com
Minimizing Thermal Gradients
Thermocouple wire can be a significant source of thermal gradients if it
conducts heat or cold directly to terminal junctions. To minimize these
errors, follow these guidelines:
Use small-gauge thermocouple wire. Smaller wire transfers less heat
to or from the measuring junction.
Run thermocouple wiring together near the screw-terminal connector
to keep the wires at the same temperature.
Avoid running thermocouple wires near hot or cold objects.
If you connect any extension wires to thermocouple wires, use wires
made of the same conductive material.
Specifications
The following specifications are typical at 25 °C, unless otherwise noted.
All voltages are relative to COM unless otherwise noted.
Input Characteristics
Number of channels................................4 thermocouple channels,
1 internal autozero channel,
1 internal cold-junction
compensation channel
ADC resolution.......................................24 bits
Type of ADC ..........................................Delta-sigma
Input range..............................................±80 mV, (not software selectable)
Common-mode range
Channel-to-COM.............................±1.5 V
Common-to-earth ground ................±250 V
Common-mode rejection ratio (0 to 60 Hz)
Channel-to-common........................95 dB
Common-to-earth ground ................>170 dB
Temperature measurement ranges..........Works over temperature
ranges defined by NIST
(J, K, R, S, T, N, E, and
B thermocouple types)