Description
The National Instruments PXI-2527 is a high-voltage, multi-channel multiplexer switch module designed for data acquisition and automated test systems within PXI and PXI Express (via hybrid slots) chassis. It functions as a front-end routing system for signal conditioning and measurement devices, such as digital multimeters (DMMs), source measure units (SMUs), and oscilloscopes.
In field deployments, the PXI-2527 is commonly utilized for automotive ECU testing, aerospace electronics validation, and component burn-in systems where multiple test points must be systematically routed to a central measurement instrument.
Commercial Availability & Lifecycle Status
- Condition: New Original / New Surplus / Refurbished (Fully Tested and Calibrated)
- Availability: In stock
- Lead Time: Ships within 1–3 business days from order confirmation
- Warranty: 12-month comprehensive warranty
- Pricing Note: Price is subject to market conditions and regional availability. Contact our sales engineering team for a firm, formal quotation.
Technical Specifications
The table below outlines the core hardware specifications, relay ratings, and performance metrics for the PXI-2527 module.
| Parameter | Value / Specification |
| Model Number | PXI-2527 |
| Part Number | 778572-27 |
| Module Type | Multiplexer |
| Relay Type | Electromechanical (Armature) |
| Switch Configurations | 1-wire (64-channel), 2-wire (32-channel), 4-wire (16-channel) |
| Max Switching Voltage | 300 V DC / 300 V AC |
| Max Switching Current | 2 A (per channel) |
| Max Switching Power | 60 W / 62.5 VA |
| Path Resistance | < 1.0 Ω (initial), < 2.0 Ω (end-of-life) |
| Max Scan Rate | 140 cycles per second |
| Relay Life Expectancy | 1 \times 10^7 cycles (mechanical), 1 \times 10^5 cycles (at full electrical load) |
| I/O Connector | 100-pin unshielded SCSI |
| Bus Connector | PXI 3U |
| Dimensions | Standard 1-slot 3U PXI module |
Hardware Architecture & Configurations
The PXI-2527 uses software-configurable mechanical armature relays to change topologies without physical rewiring. Depending on the differential requirements of the signals under test, the module can be provisioned into three distinct modes:
64-Channel 1-Wire Mode
Used for single-ended measurements where all signals share a common ground reference. This maximizes channel density for low-frequency DC or voltage monitoring.
32-Channel 2-Wire Mode
Configures the module to route differential signals (High and Low pairs). This topology is standard when interfacing with DMMs to measure resistance or differential voltage, eliminating common-mode noise.
16-Channel 4-Wire Mode
Pairs two 2-wire channels together. This is the required architecture for precise low-resistance measurements (RTDs, shunts, components < 100\ \Omega) to eliminate the effect of test lead and path resistance from the measurement equation.
Compatibility, Terminal Blocks, & Cables
To deploy the PXI-2527, specific mating accessories are required to breakout the 100-pin high-density front connector.
- TB-2627: The recommended terminal block for the PXI-2527. It is a screw-terminal enclosure that attaches directly to the front of the module, providing cold-junction compensation (CJC) for thermocouple measurements.
- SH100-100-F Cable: A shielded 100-pin cable used to connect the PXI-2527 to external custom terminal panels or mass interconnect systems (e.g., Virginia Panel or Mac Panel).
- Driver Software: Supported via the NI-SWITCH driver framework. It integrates directly with LabVIEW, LabWindows/CVI, and TestStand, and supports standard IVI (Interchangeable Virtual Instruments) protocols.
Safety and Operational Constraints
Critical Operational Note: The PXI-2527 has a maximum switching power limit of 60 W. Exceeding the simultaneous 300 V or 2 A boundaries such that the total power throughput passes 60 W will cause rapid pitting or welding of the relay contacts, rendering the channel permanently open or closed.
- Cold Switching vs. Hot Switching: To maximize the lifespan of the armature relays, execute “cold switching” wherever possible—ensure that the test stimulus signal is powered down or disconnected via the source before opening or closing the PXI-2527 relays. Hot switching at maximum rated voltage/current drastically shortens the relay life toward the 1 \times 10^5 cycles minimum limit.
- Inductive Loads: When routing inductive loads (such as external motors, solenoids, or relays), voltage spikes can exceed the 300 V threshold during break actions. External flyback diodes or snubber networks must be placed across the load to protect the module’s internal relay matrix.
Frequently Asked Questions
Can I mix different topologies (e.g., use 10 channels as 1-wire and 5 channels as 2-wire) simultaneously?
No. The module must be programmatically configured into one primary topology (64×1, 32×2, or 16×4) during initialization in the NI-SWITCH driver. You cannot run split topologies on a single PXI-2527 card at the same time.
Does the PXI-2527 support hardware triggering?
Yes. The module connects to the PXI backplane trigger lines. This allows the switch to synchronize directly with an instrument like the NI PXI-4070/4081 DMM. The DMM can trigger the switch to advance to the next channel immediately after completing a measurement without waiting for software latency from the host PC.
How do I track the health of the relays inside the module?
The NI-SWITCH driver maintains an internal relay count tracking system for the PXI-2527. You can query this data via software to determine how many cycles each individual relay has executed, allowing for predictive maintenance before a channel fails in production.
How can I verify that my wiring layout matches the internal schematic of the PXI-2527?
Because pin assignments shift dramatically between 1-wire, 2-wire, and 4-wire modes, verify your signal mapping directly with the official NI PXI-2527 Device Specifications and TB-2627 Installation Guide before supplying power to the system.
