NI PXIe-4081 PXI DMM-7 Class Board

This NI PXIe-4081 PXI DMM-7 Class Board module offers 26-bit resolution, DC voltage measurements from 10 nV to 1000 V, current measurements from 1 pA to 3 A, and resistance measurements from 10 µΩ to 5 GΩ. At a 10 V range, it maintains a basic accuracy of 12 ppm of reading + 0.5 ppm of range over two years.

Compared to its predecessor, the FlexDMM, the PXIe-4081 offers a 10-fold increase in resolution and up to 60% improvement in accuracy, while retaining the 2-year calibration cycle and patented self-calibration technology, ensuring metrological-grade accuracy across the entire operating temperature range.

The NI PXIe-4081 is the flagship model in NI's PXI digital multimeter product line, positioned as the industry's most accurate 7½-digit modular DMM. It integrates a high-resolution 1000V digital multimeter with an isolated digitizer into a single PXI Express module, providing precise measurement capabilities for automated test systems while also enabling high-speed waveform acquisition.

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Specific Tails

The PXIe-4081 PXI DMM-7 Class Board belongs to the NI PXI Digital Multimeters product line, which covers a full gradient from low-cost 6½-digit devices to high-performance 7½-digit models. The entire PXI DMM family includes the following main models: PXI-4065 (entry-level 6½-digit), PXIe-4080 (6½-digit with digitizer), PXIe-4081 (7½-digit flagship), and PXIe-4082 (6½-digit with LCR measurement).

The PXIe-4081 has applications spanning a wide range of fields, from semiconductor characterization to aerospace production testing. In the semiconductor industry, its nanovolt-level voltage sensitivity and picoampere-level current sensitivity allow for precise measurements of parameters such as device turn-off characteristics and leakage current. In the aerospace and defense sectors, its 1000V high-voltage measurement capability and metrology-grade accuracy meet the stringent testing requirements of airborne equipment and power systems. In consumer electronics and automotive electronics, its modular design allows for integration with switch matrices to construct multi-channel test systems, meeting the throughput demands of large-scale production testing.

Furthermore, the isolated digitizer mode opens up application scenarios that traditional DMMs struggle to handle, such as testing tasks that require simultaneous observation of DC level and AC ripple, including automotive ignition coil flyback voltage measurement, fuel cell stack single-cell voltage monitoring, and power supply transient response analysis.

Comparison of NI PXI DMM Product Lines

As clearly shown in the table above, the PXIe-4081 PXI DMM-7 Class Board holds a commanding position in both accuracy and voltage range within the entire NI PXI DMM product line. Compared to its siblings, the PXIe-4080 and PXIe-4082, the PXIe-4081 offers a higher resolution (7.5 bits vs. 6.5 bits), increases the maximum voltage from 300V to 1000V, the maximum current from 1A to 3A, and improves 10V range accuracy over two years from 25+6 ppm to 12+0.5 ppm, more than doubling the accuracy. The only feature missing from the PXIe-4082 is inductance/capacitance (LCR) measurement, a result of the product line's functional division—LCR measurement needs can be met by the PXIe-4082 or a dedicated PXI LCR tester.

Differentiated Technological Advantages

• ​​​​​​​26-bit FlexADC Architecture

The core technology of the PXIe-4081 is its unique FlexADC architecture—combining commercial high-speed ADC technology with a custom Σ-Δ converter to achieve continuously variable resolution from 10 bits to 26 bits. This architecture breaks the inherent contradiction of "high precision = low speed" in traditional DMMs, allowing users to flexibly choose between resolution and speed according to application requirements. The same hardware can perform precise measurements at 7.5 bits of precision as well as waveform acquisition at a rate of 1.8 MS/s.

• Solid-state High-voltage Switching Technology

Traditional DMMs rely on electromechanical relays for range switching, which suffers from issues such as contact wear, thermoelectric potential, and limited lifespan. The PXIe-4081 employs innovative solid-state devices for range selection, capable of withstanding voltages above 1000V in the off state, completely eliminating the reliability problems associated with electromechanical relays. A secondary advantage of solid-state switching is its excellent low-voltage DC thermal performance, which is extremely rare in 1000V-class DMMs.

• Metrology-grade Reference Source and 2-year Calibration Cycle

The PXIe-4081 PXI DMM-7 Class Board features one of the most stable onboard voltage references on the market, with a temperature coefficient of less than 0.3 ppm/°C and time stability of approximately 8 ppm/year. The resistance function references a single 10 kΩ high-stability metal foil resistor with a temperature coefficient of less than 0.8 ppm/°C and time stability of less than 25 ppm/year—a component originally designed for aerospace applications. It is this exceptional stability of the reference components that enables the PXIe-4081 to offer a 2-year accuracy guarantee, significantly better than the 1-year calibration cycle of most traditional benchtop DMMs, directly reducing the ownership cost and downtime of the test system.

• Self-calibration and Full-temperature Accuracy

The PXIe-4081's self-calibration function can recalibrate all voltage, resistance, and digitizer ranges within one minute, correcting all DC gain and offset drift. With self-calibration, measurement accuracy is more than 7 times higher than traditional 7½-bit DMMs, even at ambient temperatures of 50°C. The recommended self-calibration interval is every 24 hours or when the temperature change exceeds 5°C, requiring no external calibration equipment.

• Third-order DC Noise Suppression

The PXIe-4081 PXI DMM-7 Class Board offers NI's exclusive three-level DC noise suppression—Normal, Second-order, and High-order. In High-order mode, it achieves >110 dB of normal noise rejection over a 100 ms aperture time and is insensitive to power line frequency variations, meaning it maintains over 6½ bits of measurement accuracy even in noisy industrial environments.

As the latest flagship in the FlexDMM family, the PXIe-4081 continues the core technological genes established since the PXI-4070/4071 era, including the FlexADC architecture, self-calibration technology, solid-state signal conditioning, and isolated digitizer mode. Building upon this foundation, the PXIe-4081 achieves generational leaps in several dimensions: resolution increases from 23-bit to 26-bit (a 10x improvement), maximum voltage increases from 300V to 1000V, DC sensitivity increases from 100nV to 10nV, DC current sensitivity increases from 10nA to 1pA, and resistance sensitivity increases from 100µΩ to 10µΩ.

At the platform level, the PXIe-4081 adopts the PXI Express bus interface, fully utilizing the PXI platform's timed synchronization, trigger routing, and high-bandwidth data transmission capabilities—features not found in earlier PXI products. While belonging to the PXIe-408x series, the PXIe-4081 boasts superior performance across the board, positioning itself as the flagship model, while the PXIe-4080/4082 offers a more cost-effective 6½-bit configuration to cover mainstream applications.

It's important to note that the PXIe-4081 PXI DMM-7 Class Board does not support inductance and capacitance (L&C) measurements. If users require LCR measurement, they should choose the PXIe-4082 from the same series or NI's dedicated PXI LCR tester. Furthermore, the PXIe-4081 is only available for the PXI Express bus; other bus types such as PCIe or USB are not supported.

Isolation Digitizer Mode

In addition to traditional DMM functions, the PXIe-4081 also features an isolated digitizer mode, capable of acquiring DC-coupled waveforms at a maximum sampling rate of 1.8 MS/s. The waveform acquisition ranges cover two main categories: voltage and current:

• Voltage waveforms: 100 mV ~ 1000 V, 5 ranges, supporting DC or AC coupling
• Current waveforms: 100 µA ~ 3 A, 6 ranges, DC coupling

The analog bandwidth of the digitizer mode is approximately 300 kHz, meaning it can accurately acquire signals with frequencies up to 300 kHz. It's important to note that 300 kHz bandwidth and a 1.8 MS/s sampling rate are two different things—according to the Nyquist theorem, a sampling rate of 1.8 MS/s can theoretically capture signals below 900 kHz, but in practice, the analog front-end bandwidth limits the highest effective frequency to 300 kHz. Users can easily adjust the digitizer's resolution (from 10 bits to 26 bits) by changing the sampling rate.

The isolation design offers three key advantages: improved common-mode rejection (allowing safe measurement of small signals with large common-mode voltages), enhanced safety (the insulation barrier can withstand transient high-voltage spikes), and elimination of ground loops (physically blocking ground loop currents and reducing measurement noise). This is particularly important for scenarios such as fuel cell testing, high-voltage power supply monitoring, and industrial sensor signal acquisition.

Application

The PXIe-4081's versatility makes it suitable for a wide range of test and measurement scenarios:

• Semiconductor Characterization: Picoampere-level leakage current measurement, nanovolt-level voltage measurement, device IV characteristic curve scanning
• Aerospace and Defense: High-voltage system testing, precision sensor calibration, airborne equipment production testing
• Automotive Electronics: Ignition coil flyback voltage measurement, Battery Management System (BMS) testing, sensor signal acquisition
• Consumer Electronics: Power module testing, Circuit Board Functional Testing (FCT), multi-channel parallel testing
• Industrial and Energy: Fuel cell single-cell voltage monitoring, power supply transient response analysis, power quality testing​​​​​​​

In these applications, the PXIe-4081 is often used in conjunction with NI PXI switch modules to achieve high-speed scanning via hardware timing triggering on the PXI backplane, extending the measurement capabilities of a single DMM to hundreds or even thousands of test points.

The NI PXIe-4081, the flagship model of the FlexDMM family, offers industry-leading 7.5-bit measurement accuracy and 1000V high-voltage measurement capability in a compact single-slot PXI Express module. Its core competitive advantages lie in three aspects: First, metrology-grade accuracy—26-bit resolution, 12 ppm two-year basic accuracy, solid-state signal conditioning, and a highly stable reference source, making it comparable to high-end benchtop DMMs in the precision measurement field; second, its two-in-one functionality—the combination of a DMM and a 1.8 MS/s isolated digitizer, saving slots and cost while opening up transient waveform analysis capabilities; and third, the advantages of the PXI platform—hardware timing synchronization, switch-scan handshake, and tight integration with other PXI instruments, giving it overwhelming throughput and integration advantages over benchtop instruments in automated test systems.

For selection decisions, if the application requires 7.5-bit accuracy + 1000V high voltage + waveform acquisition capability, the PXIe-4081 is the best choice on the PXI platform. If only 6½-digit accuracy and a 300V range are required, the PXIe-4080 offers a more cost-effective solution; if LCR measurement functionality is needed, the PXIe-4082 should be chosen. For measurement needs exceeding 1000V or 3A, external voltage divider/shunt solutions can be used for expansion, but the corresponding accuracy reduction should be noted.

Security and Compliance Certification

Safety Standards:

• IEC 61010-1 / EN 61010-1
• UL 61010-1 / CSA C22.2 No. 61010-1

EMC Standards:

• EN 61326-1 (IEC 61326-1): Category A Emissions, Basic Immunity

• EN 55011 (CISPR 11): Group 1, Category A Emissions

• EN 55022 (CISPR 22): Category A Emissions

• EN 55024 (CISPR 24): Immunity

• AS/NZS CISPR 11: Group 1, Category A Emissions

• AS/NZS CISPR 22: Category A Emissions

• FCC 47 CFR Part 15B: Category A Emissions

• ICES-001: Category A Emissions​​​​​​​

CE Compliance Directives:

• 2014/35/EU Low Voltage Directive (LVD)
• 2014/30/EU Electromagnetic Compatibility Directive (EMC)
• 2011/65/EU Restriction of Hazardous Substances Directive (RoHS)
• 2014/53/EU Radio Equipment Directive (RED)
• 2014/34/EU Explosion-Proof Directive (ATEX)

Driver: NI-DMM

The driver for the PXIe-4081 PXI DMM-7 Class Board is NI-DMM, an IVI (Interchangeable Virtual Instrument) compatible instrument driver that supports all NI programmable digital multimeters. NI-DMM provides a unified API interface, ensuring code compatibility between different NI DMM models and reducing system upgrade and maintenance costs.

The core components of the driver include:

• Instrument Driver API: A complete set of function/property interfaces for configuring and controlling all functions of the DMM
• Interactive Soft Front Panel (SFP): Provides an interactive operating interface similar to a benchtop instrument for rapid measurement and application debugging
• Sample Library: Dozens of out-of-the-box examples covering typical application scenarios such as single measurement, multiple measurement, and advanced features.
• Help Documentation: A complete function reference and usage guide.

Bespoke Engineering & Customization Services
​​​​​​​

We understand that standard solutions cannot always fulfill unique project specifications. Our highly experienced engineering team delivers comprehensive OEM/ODM customization services tailored to your exact needs. Whether you require tailored frequency ranges, specialized triggering options, or custom enclosure components, we collaborate closely with you from concept to completion. Our agile design methodology ensures your specific application challenges are fully resolved while maintaining our uncompromising quality standards.

Why MXTD?

• 12+ Years of Expertise: Deep-rooted experience in precision measurement and control engineering.
• Innovative R&D: Cutting-edge technology driven by an expert team to meet dynamic market needs.
• Guaranteed Quality: Strict production controls and rigorous testing for reliable, long-term performance.
• Full-Cycle Support: Responsive technical assistance from pre-sales consulting to after-sales care.
• Safe & Insured Shipping: Secured, tracked, and insured logistics via industry-leading carriers.
• Customer First: Personalized services, proactive follow-ups, and fast turnaround times.

FAQs:

Q: Why can't I find the PXIe-4081 board in the NI MAX software?

A:  

• Check Driver: The NI-DMM driver must be installed; installing only NI-DAQmx will not recognize the multimeter card.
• Check Device Manager: If "PCI-to-PCI Bridge" displays a yellow exclamation mark in Windows Device Manager, it usually indicates a compatibility issue between the host BIOS and the MXI remote control system. Download and install the MXI-Express BIOS Compatibility Software.
• Reseat Hardware: Turn off the power to the computer case, move the card to a slot closer to the controller (or try a different slot), and then try again.

Q: What should I do if a blue screen (BSoD) occurs when the host computer starts up, and the board is plugged into the chassis along with other PXI boards (such as a switch matrix)?

A: 

This is a known issue that may occur when connecting via Thunderbolt in certain chassis (such as PXIe-1090). It is typically caused by driver conflicts or memory address allocation conflicts. Workaround: Update the NI-DMM driver to the latest version, or disable specific Thunderbolt-safe DMA protection settings on the host PC.

Q: How do I fix the error message "Error -1074102163" or "Failed Self-Test" on my circuit board?

A: 

This error is usually caused by the lack of self-calibration. The PXIe-4081 must be calibrated before it can pass the self-test.

Right-click the board in NI MAX and click Self-Calibrate to perform internal self-calibration. If the error persists, try repairing the NI-DMM driver.

Q: How do I perform "Adjustment" on the PXIe-4081? Why are there no adjustment buttons on its soft panel?

A: 

Unlike benchtop multimeters (such as the 3458A) where calibration can be performed directly via voice commands on the front panel, NI boards cannot be adjusted externally via a virtual soft panel. Automated calibration programming must be performed using NI's official Calibration Executive software, along with a standard Fluke regulated power supply and standard resistors.

Q: What is the purpose of the "Digitizer" mode on the PXIe-4081? How do I enable it?

A: 

The PXIe-4081 is not only a high-precision DMM, but it can also switch to a high-speed digitizer with a resolution of 1.8 MS/s and 26-bit resolution. It can be used to acquire transient currents or voltages, such as analyzing inrush currents, power consumption characteristics, and battery internal resistance of Internet of Things (IoT) or medical devices during sleep/wake cycles. This mode can be switched to in LabVIEW by calling APIs such as niDMM Configure Waveform Voltage.

Contact Us

Ready to integrate reliable PXI DMM Module control into your system? Our team is here to help you select the right configuration and provide ongoing support.

Contact our technical specialists at manager03@mxtdinfo.com  / manager02@mxtdinfo.com for detailed specifications, pricing information, or to discuss your custom requirements. We're committed to delivering the perfect NI PXIe-4081 PXI DMM-7 Class Board solution for your application needs.