The National Instruments USB-9211 (Part Number: 778976-01) is a high-precision thermocouple input device designed for reliable temperature measurement. This 24-bit device supports four channels and features a USB interface with integrated signal conditioning for seamless data acquisition. The USB-9211 comprises two components: the USB-9161 carrier and the NI-9211 module, which are provided as separate items for user convenience; the module can be easily inserted into the carrier without tools. This compact device can also be mounted on a panel, enhancing its versatility for various applications.

Each channel is equipped with built-in impedance between the thermocouple (TC) and common (COM) terminals, as well as between TC+ and COM terminals. During operation, the channels are filtered and sampled using a 24-bit Delta-sigma analog-to-digital converter (ADC). A current source is connected between the TC+ and TC- terminals to facilitate the detection of open thermocouple conditions, which results in a full-scale voltage signal. The USB-9211 minimizes offset and gain errors in most applications where thermocouples are directly connected. For measuring offset errors, an internal autozero channel is provided, optimized for ambient temperature conditions below 15 °C or above 35 °C, and remains enabled at all times. Additionally, the device incorporates an internal cold-junction compensation channel for enhanced accuracy.

The USB-9211 is compatible with a wide variety of thermocouples, including types S, T, N, J, K, and B. Although the USB-9211 has been classified as obsolete by National Instruments, it remains available for purchase and repair through Apex Waves. For further operational insights, user and maintenance manuals can be downloaded, and pricing information can be obtained by contacting a sales representative. With dimensions of 5.51 inches by 3.37 inches by 0.99 inches and a weight of 12.3 ounces, the USB-9211 combines robust performance with a lightweight design.