II. Model Interpretation

PXI: 3U single slot, standard PXI bus (compatible with PXIe chassis)

6251: High-speed version of the M series, 16AI/2AO/24DIO, 16-bit, 1.25 MS/s

M series: Multi-function, high-speed sampling + general I/O

Part number: 779117-01

Status: Out of production;

III. Technical Parameters (25℃)

1. Analog Input (AI)

Channels: 16 single-ended / 8 differential (software selectable)

Resolution: 16 bits (no bit loss)

Sampling rate: 1.25 MS/s per channel, 1 MS/s for multiple channels

Range: ±0.1/±0.2/±0.5/±1/±2/±5/±10 V (programmable) NI

Input impedance: >10 GΩ || 100 pF

Overvoltage protection: ±25 V

CMRR: 100 dB (DC–60 Hz)

FIFO: 4 k samples, supports 6 DMA channels

2. Analog Output (AO)

Channels: 2

Resolution: 16 bits

Update rate: 2.8 MS/s (per channel)

Range: ±10 V (default, software adjustable)

Drive: ±5 mA

Stabilization time: 2 μs (full scale)

3. Digital I/O (DIO)

Configuration: 24 bidirectional (5 V TTL/CMOS)

Rate: Maximum 10 MHz (hardware timing)

Protection: 2 channels support ±20 V overvoltage input

Function: Anti-jitter filtering, programmable input/output

4. Counter / Timer

Quantity: 2 32-bit channels (80 MHz base time)

Function: Event counting, frequency / period, pulse output, quadrature encoding (X1/X2/X4)

FIFO: 2 samples

5. Physical and Environmental

Size: 3U single slot (22×124×126 mm)

Operating temperature: 0～55℃

Power consumption: Approximately 8 W

Calibration: NI-MCal technology, recommended every 2 years once

IV. Interface and Communication Configuration

Front panel interface: 68-pin SCSI-II female connector (with SH68-68-EP cable, CB-68LP wiring box) NI

Bus: PXI (PCI, trigger, 10 MHz reference clock, RTSI)

Driver: NI-DAQmx, supports LabVIEW, Python, C#, TestStand

Synchronization: PXI trigger bus / RTSI, multi-module synchronization

PFI lines: 8 programmable function inputs for triggering and timing routing

V. Core Functions

High-speed dynamic acquisition: 1.25 MS/s + 16 bits, accurately captures vibration, transient voltage, high-frequency signals.

Flexible multi-channel configuration: 16AI/2AO/24DIO integration, reduces module quantity, simplifies system.

High-precision measurement: NI-PGIA2 amplifier + low drift, maintains 16-bit accuracy across all channels at full speed.

Strong real-time control: 2.8 MS/s analog output + 10 MHz digital I/O, suitable for high-speed closed-loop control.

Rich triggering and timing: analog/digital triggering, PFI routing, counter, suitable for complex timing logic.

VI. Application Scenarios

High-speed dynamic signal testing: vibration analysis, shock testing, noise measurement, modal analysis.

Power electronics testing: voltage/current transient acquisition of switching power supplies, inverters, frequency converters. Automated Test System (ATE): PCB functional testing, component parameter testing, mass production calibration.

Research and Laboratory Automation: High-speed data recording, sensor calibration, precise control.

General Multi-parameter Measurement and Control: Mixed system that simultaneously collects analog, digital, and counter signals.

VII. Installation and Maintenance Instructions

Installation and Power On

Disconnect the card when power is off, ground the chassis; after power-on, NI-DAQmx self-checks, preheats for 15 minutes.

Operating Temperature: 0–55℃. Keep the air duct unobstructed and avoid blocking the fan.

Wiring and Operation

Differential shielded lines for analog input are preferred to reduce common-mode interference; input voltage ≤ ±11 V.

Avoid frequent plugging and unplugging of 68-pin interface; it is recommended to use CB-68LP wiring box; pay attention to level matching for digital I/O.

High-speed signals should be routed away from interference sources such as power supplies and motors, and use impedance-matched cables.

Daily Maintenance and Calibration

It is recommended to conduct traceability calibration once every 2 years; built-in self-calibration compensates for temperature drift.

Keep interfaces clean, prevent dust accumulation during long-term inactivity; avoid strong vibrations and condensation.