PCI‑6281 | Product Overview

The NI PCI‑6281 is a National Instruments (NI) M series, high-precision multi-function DAQ card (18-bit AI, 2 AO, 24 DIO, no isolation), PCI bus, half-length card, featuring:

16 AI channels (18 bit/625 kS/s) + 2 AO channels (16 bit/2.86 MS/s) + 24 DIO channels + 2 counters + programmable low-pass filter

Suitable for high-precision sensor measurement, instrument-level acquisition, low-noise signals, laboratory precision testing, and high-precision closed-loop control that requires a small amount of AO.

Part number: 779109‑01; discontinued (EOL), replacement model: PCIe‑6363.

I. Basic Information

Model: PCI‑6281

Brand: National Instruments (NI)

Series: M-Series (18-bit high precision, low noise, with 2 AO, non-isolated)

Bus: PCI (3.3 V / 5 V compatible, half-length card)

Connector: 1 × 68-pin VHDCI

Driver: NI-DAQmx

Operating Temperature: 0 ~ 55 °C

Isolation: No isolation (non-isolated type)

Features: 18-bit without bit loss, built-in 40 kHz programmable low-pass filter, NI-PGIA2 amplifier, NIST calibration, 2-channel high-speed AO

II. Analog Input AI (16 channels, 18-bit high precision)

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

Resolution: 18 bits, bit loss-free guarantee

Maximum Sampling Rate: 625 kS/s (single channel); 500 kS/s (total of multiple channels) NI

Input Range (software selectable): ±0.1 V, ±0.2 V, ±0.5 V, ±1 V, ±2 V, ±5 V, ±10 V NI

Coupling: DC

Input Impedance: >10 GΩ || 100 pF

Maximum Working Voltage: ±11 V (signal + common mode) NI

CMRR: 110 dB @ DC~60 Hz NI

Filter: Built-in 40 kHz programmable low-pass (anti-aliasing)

Input FIFO: 2,047 samples NI

III. Analog Output AO (2 channels)

Channels: 2 voltage outputs

Resolution: 16 bits

Maximum Update Rate: 2.86 MS/s (per channel)

Output Range: ±5 V, ±10 V (software selectable)

Drive Capacity: ±5 mA (per channel)

Setup Time: 10 µs (to ±0.5 LSB)

Load: Minimum 1 kΩ

IV. Digital I/O (DIO, 24 channels)

Channels: 24 bidirectional TTL (non-isolated), including 8 synchronous associated DIO

Level: 5 V TTL/CMOS (compatible with 3.3 V)

Maximum Rate: 10 MHz

DO Drive: Maximum 10 mA/channel

Function: Bidirectional input/output, event triggering, handshake signal, PFI

V. Counter / Timer

Channels: 2 32-bit general-purpose counters

Clock: 80 MHz internal base

Function: Event counting, frequency / period measurement, pulse output, encoder, PWM

VI. Trigger and Synchronization

Trigger: AI analog edge / window trigger, PFI external digital trigger

Synchronization: RTSI bus multi-card synchronization

Data Transfer: DMA, interrupt, programmable I/O

VII. Installation and Usage Tips Installation

Power off and disconnect, insert into the standard PCI half-length slot, fix the retaining plate screws; after powering on, MAX will identify and self-check.

Cabling (1 × 68-pin VHDCI)

AI: Single-ended AIn + GND; Differential AI+/AI−, common mode ≤ ±11 V, no isolation against ground loop.

AO: AO + AGND, load ≥ 1 kΩ,严禁 short circuit.

DIO： TTL common ground， avoid long-distance parallel lines； PFI used as trigger / clock.

Software configuration (NI-DAQmx)

Sampling： High precision， low speed priority， enable 40 kHz low-pass filtering for noise reduction

Range： Weak signal priority ±0.1 V / ±0.2 V (18-bit advantage is obvious)

Trigger： Common edge trigger (rising / falling) Notes for Attention

No isolation, not suitable for strong industrial interference / high voltage.

AI input must not exceed ±11 V, AO must not be short-circuited.

VIII. Core Features

16 AI (18 bit/625 kS/s, low-pass filtering) + 2 AO + 24 DIO + 2 counters, no isolation

PCI half-length card, single 68-pin VHDCI, NI-DAQmx driver stable, NIST calibration

18-bit high resolution + low noise design + 2 high-speed AO, suitable for precise measurement and lightweight closed-loop control

Applicable: high-precision measurement in the laboratory, low-noise signal acquisition, sensor array, precise testing, high-resolution DAQ system requiring a small amount of AO