USB-6251 1.25 MS/s USB M Series Multifunction DAQ
Земля NI USB-6251 is a high-speed M Series multifunction data acquisition device for automated test, research, control and electronic validation. It combines fast multiplexed analog input, hardware-timed analog output, digital I/O and counter/timer resources in an external USB enclosure.
The USB-6251 provides 16 single-ended or eight differential analog inputs with 16-bit resolution. Its maximum input rate reaches 1.25 MS/s on one channel and 1.00 MS/s aggregate during multichannel scanning.
Two 16-bit analog outputs, 24 digital I/O lines and two 32-bit counters allow the device to perform coordinated stimulus, response measurement and fixture control.
Key Features of the USB-6251
- 16 single-ended or 8 differential analog inputs
- 16-bit ADC resolution
- 1.25 MS/s maximum single-channel input rate
- 1.00 MS/s maximum aggregate multichannel rate
- Seven programmable input ranges from ±0.1 V to ±10 V
- 1.7 MHz small-signal input bandwidth
- Two 16-bit analog outputs
- Up to approximately 2.86 MS/s analog output
- 24 individually programmable digital I/O lines
- Eight correlated digital I/O lines
- Two 32-bit counter/timers
- Analog and digital triggering
- USB 2.0 Hi-Speed connectivity
- Screw-terminal, BNC and mass-termination versions
- NI-DAQmx driver support
USB-6251 Technical Specifications
| Product Model | USB-6251 |
|---|---|
| Product Family | High-speed NI M Series multifunction DAQ |
| Analog Inputs | 16 single-ended or 8 differential |
| ADC Resolution | 16 bits |
| Single-Channel AI Rate | 1.25 MS/s maximum |
| Multichannel AI Rate | 1.00 MS/s aggregate |
| Input Ranges | ±0.1 V, ±0.2 V, ±0.5 V, ±1 V, ±2 V, ±5 V and ±10 V |
| Input Bandwidth | 1.7 MHz |
| CMRR | 100 dB from DC to 60 Hz |
| Analog Outputs | 2 |
| DAC Resolution | 16 bits |
| Analog Output Range | ±10 V |
| Maximum AO Rate | Up to approximately 2.86 MS/s, configuration dependent |
| Цифровой ввод-вывод | 24 individually programmable lines |
| Correlated Digital I/O | 8 Port 0 lines |
| Counters | 2 × 32-bit |
| USB Interface | USB 2.0 Hi-Speed |
| External Power | Required |
| Connector Options | Screw terminal, BNC and mass termination |
| Поддержка программного обеспечения | НИ-DAQmx |
USB-6251 Part Number and Accessories
USB-6251 orderable configurations differ by connector type and enclosure. Confirm the full part number rather than ordering only by the USB-6251 family name.
| Configuration or Accessory | Описание |
|---|---|
| USB-6251 Screw Terminal | Integrated terminals for flexible sensor and fixture wiring |
| USB-6251 BNC | Direct coaxial connections for laboratory measurements |
| USB-6251 Mass Termination | High-density connection to custom fixtures and cable assemblies |
| USB Cable | Connection to the host computer |
| External Power Supply | Required power for the enclosed USB device |
| SHC68-68-EPM Cable | Shielded cable commonly used with compatible 68-pin mass-termination accessories |
| SCB-68A Connector Block | Shielded screw-terminal connection for compatible 68-pin configurations |
1.25 MS/s Analog Input
The USB-6251 supports a maximum 1.25 MS/s sampling rate when acquiring one analog input. During multichannel scanning, the maximum aggregate rate is 1.00 MS/s.
This multiplexed architecture is appropriate for fast control signals, electronic waveforms and transient measurements that do not require simultaneous sampling across channels.
Seven Programmable Input Ranges
Input ranges from ±0.1 V through ±10 V provide flexibility for both low-level and standard laboratory signals. Selecting a narrower range increases ADC utilization and measurement sensitivity.
High-Speed Analog Generation
Two analog outputs can generate static voltages, arbitrary waveforms and periodic signals. Hardware timing provides more consistent waveform generation than repeated software commands.
The outputs should not be used as programmable power supplies. External amplification is required when the DUT needs higher current or power.
USB-6251 Applications
- High-speed laboratory data acquisition
- Electronic functional testing
- Stimulus-and-response measurement
- Automated production testing
- Transient voltage capture
- Waveform generation
- Motor and encoder testing
- Digital fixture control
- Research and prototype validation
Electronic Device Validation
The USB-6251 can generate analog stimulus while measuring DUT voltages and monitoring digital status signals. Counters can measure frequency, pulse width and encoder position.
Portable High-Speed Measurement
The external enclosure allows a high-performance DAQ system to be connected to a desktop or laptop without opening the computer. An external power supply is still required.
USB-6251 Installation Workflow
Step 1: Confirm the Connector Version
Identify whether the unit uses BNC, screw terminals or mass termination and select compatible accessories.
Step 2: Install NI-DAQmx
Install a driver version that supports the device, operating system and development environment.
Step 3: Connect External Power
Use the required approved supply and verify polarity and connector security.
Step 4: Connect USB
Use a high-quality USB 2.0 cable and avoid unnecessary hubs or extension cables.
Step 5: Configure Input Ranges
Select the smallest suitable voltage range and the correct differential, RSE or NRSE wiring mode.
Step 6: Validate Maximum Throughput
Test the complete channel list and application at the intended sample rate before deployment.
USB-6251 Troubleshooting
The Device Appears in NI MAX but Acquisition Fails
Check whether another task has reserved the device. Stop other NI-DAQmx tasks and run a self-test.
The Device Cannot Maintain 1.25 MS/s on Multiple Channels
The 1.25 MS/s rating applies to single-channel acquisition. Multichannel operation is limited to 1.00 MS/s aggregate.
Signals Are Distorted After Channel Switching
Reduce source impedance, increase settling time or add buffer amplifiers between high-impedance sensors and the DAQ inputs.
Analog Output Timing Is Irregular
Use hardware-timed waveform generation rather than software-timed single-point updates.
USB-6251 Comparison
| Модель | AI Channels | AI Resolution | Maximum AI Rate | AO Channels |
|---|---|---|---|---|
| USB-6221 | 16 | 16 bits | 250 kS/s | 2 |
| USB-6251 | 16 | 16 bits | 1,25 МСм/с | 2 |
| USB-6259 | 32 | 16 bits | 1,25 МСм/с | 4 |
Choose the USB-6251 for high-speed applications requiring 16 analog inputs. Choose the USB-6259 when the system needs twice the analog input count, four analog outputs and 48 digital lines.
USB-6251 Frequently Asked Questions
What is the maximum analog input rate?
The USB-6251 supports 1.25 MS/s on one channel and 1.00 MS/s aggregate for multichannel acquisition.
How many analog outputs are included?
It provides two 16-bit analog output channels.
Does the USB-6251 require external power?
Yes. The enclosed USB version requires an appropriate external DC power supply.
Is the USB-6251 simultaneously sampled?
No. It uses a multiplexed analog input architecture with one ADC shared by the active channels.
Which driver supports it?
The USB-6251 is controlled through NI-DAQmx.
Recommended Related Products
- USB-6221 Multifunction DAQ Device
- USB-6255 80-Channel Multifunction DAQ
- USB-6259 High-Density Multifunction DAQ
- USB-6289 18-Bit Multifunction DAQ
Request a Quote for the USB-6251
Contact us for availability, connector selection and project pricing for the NI USB-6251 high-speed multifunction DAQ device.
