The National Instruments PXI-6221 is a versatile PXI Multifunction I/O module designed to meet the demands of a variety of applications, ranging from laboratory automation and research to design verification and manufacturing testing. It features 16 analog inputs with a 16-bit resolution and a sampling rate of 250 kS/s, along with 16 analog outputs and 24 digital I/O channels, making it suitable for seamless communication and data acquisition. The module includes two 32-bit counters/timers and offers capabilities for digital signal processing. The PXI-6221 operates with either screw terminal or BNC termination through a 68-pin VHDCI I/O connector and requires one shielded or unshielded cable for connectivity. Designed for use in electrically noisy or harsh environments, this module supports high-voltage measurements through SCC or SCXI signal conditioning modules, ensuring reliable performance. The NI-DAQmx driver and accompanying setup utility simplify configuration and data assessment, enabling programming in LabVIEW, LabWindows/CVI, and Measurement Studio. The PXI-6221 is built with essential reliability features, including isolation to prevent ground loops and protect against voltage transients. With a recommended operating temperature range of 0 ºC to 55 ºC and a robust mechanical configuration weighing 5.7 oz, this device is ideal for demanding industrial applications. While the PXI-6221 has been designated as a mature product, it remains available for purchase and repair, ensuring continued support for users.