I. Basic Information

Model: PCIe-6251 (M Series)

Part Number: 779512-01

Bus: PCIe ×1 (Gen1)

Status: EOL (Inventory / Second-hand)

Drivers： NI-DAQmx (Recommended)， Traditional NI-DAQ

Systems： Windows 7/10/11 (32/64-bit)， Linux

II. Core Specifications (Easy to Understand)

✅ Analog Input AI (16 channels)

Channels: 16 single-ended (SE) / 8 differential (DIFF)

Resolution: 16 bits (no bit loss)

Maximum Sampling Rate: 1.25MS/s (single channel); 1MS/s (multiple channels)

Voltage Range (software selectable):

±10V, ±5V, ±2V, ±1V, ±0.5V, ±0.2V, ±0.1V

Input Impedance: 10GΩ

FIFO: 4095 samples

?? Analog Output AO (2 channels)

Channels: 2 voltage outputs

Resolution: 16 bits

Maximum Update Rate: 2.86MS/s (1 channel); 2MS/s (2 channels)

Range: ±10V, ±5V

Drive: ±5mA/channel

??️ Digital I/O DIO (24 channels)

Channels: 24 bidirectional TTL (5V)

Among them, 8 channels are Correlated DIO, supporting hardware timing

Mode: Input/Output can be software-configured

Rate: Up to 10MHz (hardware)

⏱️ Counter/Timer (2 channels)

32-bit counter, 80MHz base frequency

Function: Encoder (quadrature), PWM, event counting, frequency measurement

Note: The counter cannot be used as both encoder and PWM at the same time

III. Interfaces and Physical

Connector: 68-pin VHDCI (high density)

Size: Full-height PCIe card (16.8×11.1cm)

Power Supply: PCIe bus power supply (≈12W)

Temperature: 0°C ~ 55°C (operating)

IV. Typical Applications

Sensor data acquisition: temperature, pressure, strain, voltage signals

Electronic testing: component characteristics, prototype verification, closed-loop control

Laboratory automation: small test system, teaching experiment

Motion control assistance: encoder position feedback, PWM output

V. Alternative Models (Upgrade Preferred)

✅ Directly compatible (X series, stronger performance, in stock)

PCIe‑6361: 16AI/2AO/24DIO, 2MS/s, PCIe ×1, in stock

PCIe‑6353: 32AI/4AO/48DIO, 1.25MS/s, PCIe ×1, in stock

✅ Cost-effective alternative (entry-level)

PCIe‑6221: 16AI/2AO/24DIO, 250kS/s, PCIe ×1, in stock VI. Common Questions

⚠️ Out of Production: The new system prioritizes PCIe-6361. The driver is fully compatible.

⚠️ 68-pin VHDCI: Wiring requires dedicated cables (such as SHC68-68).

⚠️ Counter Mutual Exclusion: The encoder and PWM cannot use the same counter simultaneously.