II. Model Interpretation

PXI: Compliant with the PXI industrial bus standard, supporting installation and use in PXIe mixed slots

2568: The model code of the NI universal relay module series, representing a 32-channel SPDT universal electromechanical relay

Full name: PXI-2568 32-Channel SPDT PXI Relay Module

Topology identifier: NISWITCH_TOPOLOGY_2568_32_SPDT, the hardware topology is fixed and does not support software reconfiguration

III. Technical Parameters

(1) Switching and Electrical Characteristics

Topology: 32 independent SPDT (Form C), each channel includes a common terminal COM, a normally open terminal NO, and a normally closed terminal NC

Relay type: Electromechanical non-latching relay, with gold-plated contacts

Maximum switching voltage: 150 VDC / 125 VAC (CAT I safety level)

Maximum switching/carrying current per channel: 2 A

Maximum switching power: 60 W DC, 62.5 VA AC (power frequency)

On-state resistance: Typical value < 50 mΩ

Thermal offset: Typical value < 1 µV

Operating bandwidth: DC ~ 10 MHz

Action time: Typical 2 ms, maximum 4.4 ms

Insulation withstand voltage: Channel-to-channel, channel-to-ground withstand voltage 150 Vrms

(2) Life and Scan Parameters

Mechanical life: 2×10⁷ on-off cycles

Full-load electrical life: 1×10⁵ on-off cycles

Scan list: Maximum support 1024-step programmable scan sequence

Full-channel scan rate: Maximum 115 times/second

(3) Trigger and Control

Trigger channels: Support hardware trigger bus from PXI backplane Trigger 0 to Trigger 7

Minimum trigger pulse width: 150 ns

Board-level functions: Each relay channel is equipped with an independent counter unit for life monitoring

(4) Physical and Environmental Parameters

Form specification: Standard 3U PXI single-slot module

Front-end connector: 78-pin D-SUB female connector

Form size: 216 mm × 20 mm × 130 mm

Weight: Approximately 0.32 kg

Power supply method: 5 V power supply from PXI backplane, typical power consumption 5.0 W

Operating temperature: 0 ℃ ~ 55 ℃

Storage temperature: -20 ℃ ~ 70 ℃

Relative humidity: 5% ~ 85%, no condensation

IV. Interface and Communication Configuration

Front-end I/O Interface

All external signals of the module are centralized and led out through the 78-pin D-SUB female connector, including 32 complete SPDT signal channels (COM/NO/NC), and the remaining pins are shielding ground and reference ground. All channels are electrically isolated from each other, and a single channel failure will not affect the normal operation of other channels.

Bus and Software Communication

Bus interface: Standard PXI backplane bus, automatically acquires power, clock, and trigger signals, compatible with PXIe chassis mixed slots.

Driver: Standard NI-SWITCH driver, compliant with IVI instrument driver specification.

Software support: Compatible with mainstream development environments such as LabVIEW, TestStand, LabWindows/CVI, Python, etc.

Basic functions: Can complete hardware identification, channel status reading, scan sequence editing, trigger mode configuration, and relay on-off count query through NI MAX.

Synchronization capability: Relying on the PXI trigger bus, achieve high-precision synchronous switching of multiple modules and multiple test instruments.

V. Core Functions High channel density: Integrated 32-channel SPDT switches in a single 3U slot, effectively saving chassis slots and suitable for large-scale multi-channel signal switching systems.

Precise signal processing: Low on-resistance design and low thermal offset, significantly reducing measurement errors, compatible with low-level analog precision signal circuits.

Programmable scanning: Built-in 1024-step scanning list, pre-editing switching logic, automatically executed by hardware, enhancing the efficiency of automated testing.

Hardware synchronous triggering: Supports PXI backplane hardware triggering, precise timing when multiple modules switch simultaneously, meeting the requirements of high-speed parallel testing.

Relay life monitoring: Board-mounted independent counter, real-time recording of each relay's on-off times, supporting predictive maintenance, reducing unplanned downtime.

Wide range compatibility: DC~10 MHz bandwidth, compatible with low-voltage DC and industrial frequency AC control signals, suitable for a wide range of applications.

Six. Application scenarios

Semiconductor, electronic component automated functional testing, achieving multi-channel signal selection for chip pins.

Industrial data acquisition system, multi-measurement point sensor analog signal multiplexing.

Automotive electronic testing, used for vehicle wiring, on-board low-voltage control circuit continuity detection.

Industrial automation testing equipment (ATE), multi-channel control signal, small power load program-controlled switching.

Laboratory research and development platform, multi-channel signal routing, loop switching and comparative testing.

Large-scale distributed measurement and control system, building a high-density switch array, unified scheduling of multiple test signals.

Seven. Usage and Maintenance Instructions

Usage points

Installation: Insert the module into the 3U standard slot of the PXI chassis, lock the panel screws, ensure reliable backplane contact, and avoid strong vibration and strong electromagnetic interference environments.

Connection: Use matching 78-pin D-SUB cables, gently insert and pull, do not pull forcefully; for precision signal circuits, it is recommended to use shielded cables and reliable grounding.

Electrical limits: Strictly follow the 150 V, 2 A rated parameters, prohibit overpressure and overcurrent operation; for inductive loads such as drive coils and motors, external series diodes or surge suppressors must be connected to prevent reverse high voltage from damaging contacts.

Trigger mode: For routine debugging, use software immediate triggering; for multi-module synchronization and high-speed scanning scenarios, enable PXI hardware triggering.

Power-on specifications: Complete wiring before powering on, disconnect the signal lines when power is off, do not plug or unplug while powered on, avoid arc burn to contacts.

Maintenance instructions

Regular inspection: Inspect D-SUB connectors every quarter, check for looseness, oxidation, and dust accumulation, and clean promptly.

Life management: Regularly read the relay on-off times using NI-SWITCH, when the number of times approaches 1×10⁵ times under load conditions, plan for replacement in advance.

Environmental control: Maintain a dry and ventilated working environment, keep the temperature at 0~55 ℃, avoid condensation and dust accumulation.

Fault handling: When a channel is abnormal, check the wiring and grounding status first; the relay of this module cannot be replaced on-site, hardware faults require overall module replacement or factory repair.

Storage requirements: When not in use for a long time, disconnect all cables, install dust protection on the interface, store in a dry environment at - 20~70 ℃, away from high temperatures, corrosion, and strong magnetic fields.

Calibration: It is recommended to conduct a functional calibration once a year, test indicators such as on-off status, conduction resistance, etc., to ensure test accuracy.