The National Instruments USB-6221 is an M Series multifunction data acquisition module delivering 16 analog input channels, 2 analog outputs, and 24 digital I/O lines over USB connectivity. Operating at up to 250 kS/s for analog input sampling and 833 kS/s for analog output updates, this 16-bit device supports data logging, automated testing, laboratory research, and embedded OEM applications. Bus-powered operation and compact form factor enable portable deployment without external power supplies.
Technical Specifications
Analog Input
• 16 single-ended or 8 differential channels
• 16-bit resolution with no missing codes guaranteed
• Sampling rate up to 250 kS/s
• Input ranges: ±0.2 V, ±1 V, ±5 V, ±10 V
• Maximum working voltage ±11 V referenced to AI GND
• Timing accuracy 50 ppm of sample rate; 50 ns timing resolution
• Input bias current ±100 pA
• Absolute accuracy on 10 V range: 3,100 µV (at 3σ coverage)
Analog Output
• 2 channels, 16-bit resolution
• Update rate up to 833 kS/s
• ±10 V maximum voltage range with 4 selectable ranges
• Range accuracy: 3,100 µV (±10 V) to 112 µV (±200 mV)
Digital I/O
• 24 channels with TTL logic levels
• Up to 24 clocked digital lines
• Minimum input pulse width 12.5 ns
• Maximum source frequency 80 MHz
• Digital drive current 24 mA
• Supports programmable input filters, handshaking, and pattern I/O
Counters/Timers
• 2 counter channels, 32-bit resolution
• Timebase stability 50 ppm
• Maximum input frequency 80 MHz
• Pulse generation supported
– Key Features
• Bus-powered USB design eliminates external power requirements
• DC input coupling for analog measurements
• Screw terminal or BNC connector options; OEM variants available
• Signal conditioning required for inputs exceeding ±10 V
– Typical Applications
Data logging, automated test systems, laboratory instrumentation, embedded OEM integration.
– Compatibility & Integration
Note: USB-6221 is a legacy product. National Instruments recommends the X Series USB-6341 for new designs.
