The NI PXI-6251 is a 16-bit multifunction DAQ module engineered for PXI chassis integration, delivering simultaneous analog input, output, and digital I/O in a single slot. It provides 8 differential (or 16 single-ended) analog input channels at 1.25 MS/s per channel, 2 analog output channels, 24 digital I/O lines, and 2 programmable counters/timers, making it suitable for automated test, research, and manufacturing environments where precision measurement and control are required.
Technical Specifications
-# Analog Inputs
• 8 differential or 16 single-ended channels
• 16-bit resolution
• Single-channel sample rate: 1.25 MS/s maximum; multichannel aggregate: 1.00 MS/s
• Input ranges: ±0.1 V to ±10 V (all channels share same range)
• Input impedance (device on): >10 GΩ || 100 pF; (device off): 820 Ω
• Input bias current: ±100 pA
• Crosstalk at 100 kHz: -75 dB (adjacent), -95 dB (non-adjacent)
• Small signal bandwidth: 1.7 MHz (-3 dB)
• FIFO depth: 4,095 samples; scan list memory: 4,095 entries
• Timing resolution: 50 ns; accuracy: 50 ppm of sample rate
• Overvoltage protection (device on): ±25 V on up to four AI pins; ±20 mA maximum input current during overvoltage
• Maximum working voltage: ±11 V of AI GND
• CMRR: 100 dB (DC to 60 Hz)
• Settling time: ±60 ppm or ±15 ppm of full-scale step
-# Analog Outputs
• 2 channels, 16-bit resolution
• Output ranges: ±10 V, ±5 V
• FIFO: 8,191 samples shared
• Settling time: 15 ppm (1 LSB) full-scale step
• Supports periodic and non-periodic waveform modes with host-buffered dynamic update
• Power-on glitch: 1.5 V peak for 1.5 s
-# Digital & Counter I/O
• 24 digital I/O channels (TTL/CMOS)
• 2 counters/timers, 32-bit resolution
• Counter measurements: two-edge separation, edge counting, period, pulse, semi-period
• Quadrature encoder support: 1X, 2X, 4X modes plus count-and-direction (no encoder filtering)
• PWM output modes: duty cycle, frequency, or period
– Key Features
• DC input coupling with high input impedance and low bias current
• Excellent crosstalk isolation for adjacent and non-adjacent channels
• Deep onboard FIFO and scan list memory for efficient data streaming
• Flexible analog input ranges with single-range constraint
• Multichannel timing with 50 ns resolution and 50 ppm accuracy
– Typical Applications
• Automated test equipment (ATE) and production testing
• Laboratory data acquisition and research instrumentation
• Manufacturing process monitoring and control
• Precision analog and digital measurement systems
– Compatibility & Integration
Designed for PXI Express and PXI systems, the PXI-6251 integrates with NI software platforms for system configuration and real-time data processing.
