II. Model Interpretation

PXI: Standard PXI bus, compatible with PXI/PXIe mixed slots.

2720: NI programmable resistor series code, representing an 8-bit, 10-channel, 0–255Ω basic type resistor module NI.

Full name: PXI-2720 8-bit 10-channel programmable resistor module.

Topology: 8-bit resistor network per channel (2⁸ = 256 steps), 1Ω step size, independent channel control NI.

III. Technical Parameters

(1) Core Resistance Characteristics

Number of channels: 10 independent channels NI

Resolution: 8 bits (1Ω step size) NI

Resistance range: 0Ω–255Ω (per channel) NI

Basic accuracy: ±0.5% (23℃) NI

Temperature coefficient (TCR): 100 ppm/℃ NI

Typical channel accuracy:

20Ω–64Ω: <5.0%

64Ω–255Ω: <2.0% NI

(2) Electrical Rated Values

Maximum voltage between channels: 60 VDC / 30 VAC (peak) NI

Maximum current per channel: 100 mA

Maximum power per channel: 1 W

(3) Switches and Relays

Relay type: Reed Relay

Action/Release time: Typical 250 μs NI

Upper limit for simultaneous drive: 89 relays NI

Mechanical life: 1×10⁷ times (1 V/10 mA)

(4) Physical and Environmental

Form: Standard 3U PXI single-slot module

Front-end connector: 37-pin D-SUB (main I/O) + 2×2 Micro-Fit (DMM sensing)

Size: 216 mm × 20 mm × 130 mm

Weight: Approximately 0.32 kg

Power supply: PXI backplane 3.3 V/5 V; typical power consumption 2.5 W

Operating temperature: 0 ℃–55 ℃

Storage temperature: –20 ℃–70 ℃

Humidity: 5%–85%, no condensation

IV. Interface and Communication Configuration

(1) Front-end I/O Interface

37-pin D-SUB (male): 10 differential channels (CHx+/CHx‑), bus positive/negative (Bx+/Bx‑), DMM sensing (HI/LO, HI SENSE/LO SENSE) NI.

2×2 Micro-Fit: Auxiliary DMM connection, supports 4-wire Kelvin measurement, eliminates lead resistance error.

(2) Bus and Software Communication

Bus interface: PXI backplane, supports PXIe mixed slot / PXI peripheral slot.

Driver: NI-SWITCH, compliant with IVI specification.

Software support: LabVIEW, TestStand, LabWindows/CVI, Python, C, .NET.

Basic functions: NI MAX can hardware recognize, channel resistance configuration, relay status monitoring, life counting.

Trigger capability: Supports PXI backplane Trigger 0–7, for multi-module synchronous switching.

V. Core Functions

10-channel independent programmable resistors: per channel 0–255Ω, 1Ω step size, precise analog RTD, potentiometer, strain bridge, etc. resistance signals NI.

8-bit high-precision resistor network: basic accuracy ±0.5%, above 64Ω accuracy better than 2%, meets calibration-level testing requirements NI.

4-wire Kelvin measurement: dedicated sensing interface, eliminates cable resistance influence, improves measurement accuracy. HIL environment simulation: Quickly simulate changes in sensor resistance such as temperature, displacement, and pressure, for ECU / controller closed-loop testing by NI.

Relay lifespan monitoring: The onboard counter records the number of on/off cycles, supporting predictive maintenance and reducing the risk of downtime.

Compact single-slot design: 3U PXI single-slot integrates 10 channels, saving cabinet space and suitable for multi-channel high-density testing.

Six. Application scenarios

Hardware-in-the-Loop (HIL) testing: Simulation of resistance sensor signals for automotive ECU, industrial controllers, and avionics equipment by NI.

RTD / thermocouple calibration: Simulate RTD resistance values such as PT100/PT1000 for temperature measurement system calibration and verification by NI.

Potentiometer / voltage divider testing: Simulate variable resistance inputs such as knobs and position sensors, testing circuit response and accuracy by NI.

Strain bridge / pressure sensor testing: Simulate changes in bridge resistance to verify the linearity and sensitivity of amplification circuits and acquisition systems by NI.

Automated production testing: Batch testing of resistance-type sensors, instruments, and controllers for input impedance and signal acquisition accuracy by NI.

Seven. Usage and Maintenance Instructions

(1) Installation and Power On

Install on PXIe mixed slots or PXI peripheral slots, avoiding pure PXIe slots.

Before installation, power off, fully insert the module and tighten the panel screws.

After powering on, confirm the device identification is normal and there are no errors in NI MAX.

(2) Connection and Operation

Use 37-pin D-SUB cables, differential connection (CHx+/CHx‑), to avoid common ground interference.

For high-precision measurement, enable 4-wire Kelvin mode, connect HI/LO and Sense lines, eliminating lead resistance.

Each channel current ≤ 100 mA, power ≤ 1 W, to prevent relay contacts from burning out.

Programming control: Set channel resistance, configure scan sequence and trigger through NI-SWITCH API.

(3) Maintenance and Lifespan

Regularly read the number of relay on/off cycles in NI MAX, replace when approaching 1×10⁷ times.

Maintain ventilation and heat dissipation, working temperature ≤ 55 ℃, avoid accelerating aging due to high temperature.

Avoid overpressure and overcurrent operations to prevent contact oxidation or adhesion.

When not in use for a long time, store in a dry environment (-20 ℃ to 70 ℃), avoid moisture oxidation of contacts.