USB-9211/9211A User Guide and Specifications
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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)
