High-Vibration Application Connections; Common-Mode Voltage; Open Thermocouple Detection; Input Impedance - National Instruments NI-9213 Getting Started

NI-9213 Getting Started
Shield
TC+
Thermocouple
TC–
COM
V
NI 9213
reference
Connect the shield to a common-mode voltage reference on the thermocouple.
A valid common-mode voltage reference is a voltage that is within ±1.2 V of the
common-mode voltage of all the connected thermocouples

High-Vibration Application Connections

If your application is subject to high vibration, NI recommends that you use the
NI-9940 backshell kit to protect connections to the NI-9213.

Common-Mode Voltage

The NI-9213 common-mode range is the maximum voltage between any channel
and COM. If COM is not connected, then the common-mode voltage range is the
maximum voltage between any two channels. The NI-9213 measures the common-
mode voltage level of each channel and returns a warning in the software if the
signal is outside the common-mode voltage range.

Open Thermocouple Detection

Each channel has an open thermocouple detection (OTD) circuit, which consists of
a current source between the TC+ and TC- terminals. If an open thermocouple is
connected to the channel, the current source forces a full-scale voltage across the
terminals.

Input Impedance

Each channel has a resistor that produces an input impedance between the TC and
COM terminals. The gain and offset errors resulting from the source impedance of
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