The National Instruments PXI-6225 Multifunction I/O Module (Part Number: 779296-01) is a versatile device from the M Series designed for data acquisition applications. It provides 40 differential or 80 single-ended analog input channels, a resolution of 16 bits, and supports a maximum sampling rate of 250 kS/s, making it suitable for high-speed data collection. The module features two analog output channels and 24 digital I/O/PFI channels, enhancing its multifunctionality.

Key components of the PXI-6225 include dual 68-pin VHDCI I/O connectors, ground-reference settings, an instrumentation amplifier (NI-PGIA), and multiplexers (mux). The I/O connectors facilitate the connection of various analog input signals, while ground-reference settings accommodate referenced single-ended, differential, and non-referenced single-ended input modes. The NI-PGIA amplifier reduces settling times across input ranges, enabling consistent precision even during rapid channel sampling. The multiplexers allow single AI channels to be routed to the ADC through the NI-PGIA.

The PXI-6225 can interface with floating signal sources, including optical isolators, thermocouples, isolation amplifiers, transformers, and battery-powered devices. For input signals below 1 V, differential connections are recommended, especially in noisy environments or where long cable runs exceed 10 feet. Conversely, for higher input signals above 1 V or shorter lead lengths, non-referenced single-ended connections are appropriate.

It is advisable to allow a warm-up time of 15 minutes for optimal performance, and annual calibration is recommended. The module, weighing 6.1 oz and conforming to the standard 3U PXI form factor, operates within a temperature range of 0 °C to 55 °C and can be stored in -20 °C to 70 °C temperatures, with a humidity tolerance of 10% to 90% RH. Although the PXI-6225 has been declared obsolete by National Instruments, it remains available for purchase and repair through Apex Waves, ensuring continued support for users.