The National Instruments USB-6251 is a sophisticated multifunction I/O device designed for portable data acquisition applications. This device supports a variety of connector types, including options with screw terminals, BNC connectors, and mass terminal connectors, allowing for versatile integration into different systems. The USB-6251 features 8 differential or 16 single-ended analog input channels with a maximum sampling rate of 1.25 MS/s for single-channel operation or 1.00 MS/s when multiple channels are used. It provides a comprehensive input range of ±1 V, ±2 V, ±5 V, ±10 V, ±0.1 V, ±0.2 V, and ±0.5 V, with a high input impedance of 10 GΩ and DC input coupling.

In addition to its input capabilities, the USB-6251 includes two analog output channels with output sampling rates of 2.86 MS/s for individual channels and 2.00 MS/s per channel when both are used. The output range can deliver signals of ±5 V and ±10 V with a maximum output current of ±5 mA, featuring DC output coupling. The device is compatible with USB 2.0 interfaces, ensuring easy connectivity to laptops and other portable computing platforms.

The USB-6251 is constructed with dimensions varying by model—screw terminal models measure 10.5 x 6.73 x 1.75 inches and weigh 10 oz, while the BNC model measures 11.25 x 6.7 x 2.7 inches, and the mass termination model measures 7.4 x 6.73 x 1.75 inches and weighs 12.8 oz. The device operates effectively within an ambient temperature range of 0 ºC to 45 ºC and can be stored between -20 ºC and 70 ºC, with a humidity resistance of 10% to 90% non-condensing. For maintaining optimal performance, it is recommended to allow a warm-up time of 30 minutes and calibrate the device every two years. The USB-6251 is part of the M Series and comes with a three-year warranty, along with user and maintenance manuals available for download.