The NI PCI-6221 is a multifunction data acquisition board for PCI bus systems, delivering 16-bit analog input, analog output, and digital I/O in a single card. It provides 16 single-ended or 8 differential analog input channels at up to 250 kS/s aggregate sampling, 2 analog output channels with matching bandwidth, and 24 individually programmable digital I/O lines. The 68-pin VHDCI connector enables high-density signal integration for industrial and laboratory environments including data logging, automated testing, and process control.
Technical Specifications
Analog Input
• 16 single-ended or 8 differential channels
• 16-bit resolution
• 250 kS/s aggregate sampling rate
• Software-selectable input ranges: ±0.1 V, ±0.2 V, ±0.5 V, ±1 V, ±5 V, ±10 V; ±0.1 V to ±5 V unipolar
• Input impedance: 10 MΩ || <15 pF (differential); 5 MΩ || <30 pF (single-ended)
• 150 µV RMS typical noise (100 kS/s, ±1 V range)
• 70 dB typical CMRR (DC to 60 Hz)
• Programmable input attenuation: 1x, 10x
Analog Output
• 2 channels
• 16-bit resolution
• 250 kS/s aggregate update rate
• Software-selectable output ranges: ±0.1 V, ±0.2 V, ±0.5 V, ±1 V, ±5 V, ±10 V
• Output impedance: <10 Ω
• 2.5 V/µs typical slew rate
• ±0.5 LSB typical DNL and INL
Digital I/O
• 24 channels, individually programmable direction
• TTL/CMOS compatible (0 V to 5 V)
• Input voltage range: -0.5 V to 5.25 V
Timing & Synchronization
• 20 MHz onboard clock
• External clock input supported
• Sample clock and reference clock outputs
• Digital and analog edge triggering; software triggering
• Onboard watchdog timer
– Key Features
68-pin VHDCI connector for compact signal routing. DC input coupling on analog channels. PCI bus-powered operation consuming <3.0 W typical. Standard PCI form factor (182 mm length, 107 mm height).
– Compatibility & Integration
Supported across Windows, macOS, and Linux. Compatible with NI-DAQmx, LabVIEW, LabWindows/CVI, Measurement Studio, and C/C++ / .NET development environments.
