II. Model Interpretation

PXI: Compliant with the PXI industrial bus standard, can be used in PXIe mixed slots.

2571: The model code of the NI universal relay module series, representing 66-channel SPDT latch-type electromechanical relay.

Full name: PXI-2571 66-Channel SPDT PXI Relay Module.

Topology Identifier: NISWITCH_TOPOLOGY_2571_66_SPDT, the hardware topology is fixed and cannot be reconfigured by software - NI.

III. Technical Parameters

(1) Switching and Electrical Characteristics

Topology: 66 independent SPDT (Form C) latches, each channel includes COM (common terminal), NO (normally open terminal), and NC (normally closed terminal) - NI.

Relay Type: Electromechanical latch relay, gold-plated contacts, pulse-driven coil (only power consumption during switching moment) - NI.

Maximum Switching Voltage: 100 VDC / 100 Vrms (CAT I), pulse withstand voltage 500 V.

Single-channel Maximum Switching / Carrying Current: 1 A.

Maximum Switching Power: DC 60 W, AC 62.5 VA (DC ~ 60 Hz).

On-Resistance: Typical value < 50 mΩ.

Thermal Offset: Typical value < 1 µV.

Operating Bandwidth: DC ~ 35 MHz.

Action Time: Typical 1.5 ms, maximum 3 ms.

Insulation Voltage: Channel-to-channel, channel-to-ground 150 Vrms.

Minimum Load: 20 mV / 1 mA.

(2) Life and Scan Parameters

Mechanical Life: 2×10⁷ on-off cycles.

Full-load Electrical Life: 1×10⁵ on-off cycles.

Scan List: Maximum 32,000 programmable scan sequences.

Full-channel Scan Rate: Up to 145 times / second.

(3) Trigger and Control

Trigger Channels: Supports hardware trigger on PXI backplane from Trigger 0 to Trigger 7.

Minimum Trigger Pulse Width: 150 ns (when digital filtering is disabled).

Built-in Function: Each relay channel has an independent counter for life monitoring; latch state is maintained when power is off - NI.

(4) Physical and Environmental Parameters

Form Specification: Standard 3U PXI single-slot module.

Front-end Connector: 200-pin LFH matrix male connector.

Form Size: 216 mm × 20 mm × 130 mm.

Weight: Approximately 0.17 kg (6.1 oz).

Power Supply: PXI backplane 5 V/3.3 V power supply, typical power consumption 6 W (5 V) + 2.5 W (3.3 V); latch state has almost zero power consumption.

Operating Temperature: 0 ℃ ~ 55 ℃.

Storage Temperature: -20 ℃ ~ 70 ℃.

Relative Humidity: 5% ~ 85%, no condensation.

Vibration: Operating 5 Hz ~ 500 Hz, 0.31 g_rms; Non-operating 5 Hz ~ 500 Hz, 2.46 g_rms - NI.

IV. Interface and Communication Configuration

Front-end I/O Interface

All external signals are led out through the 200-pin LFH matrix male connector, including 66 complete SPDT channels (COM/NO/NC), and the remaining pins are shielding ground and reference ground. Electrical isolation between channels, a single-channel failure does not affect other channels; when the latch relay is powered off, it maintains the current state, no continuous power supply is required - NI.

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 specifications.

Software support: Compatible with LabVIEW, TestStand, LabWindows/CVI, Python, etc.

Basic functions: NI MAX can perform hardware identification, channel status reading, scan editing, trigger configuration, on-off count query, and latch state setting.

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

VII. Core Functions

High-density SPDT switching: 66 SPDT channels in a single 3U slot, featuring common terminals / normally open / normally closed, suitable for complex signal routing with NI.

Locking low-power design: Only consumes power during switching, zero power consumption in steady state, suitable for long-term operation and low-power test systems with NI.

High-frequency precise signal processing: 35 MHz bandwidth, low on-resistance, low thermal offset, suitable for high-frequency analog and low-level precise signals.

High-speed programmable scan: 32,000-step scan list, executed by hardware automatically, enhancing the throughput of automated testing.

Hardware synchronous trigger: PXI backplane trigger, precise timing, suitable for high-speed parallel testing and multi-instrument coordination.

Relay life monitoring: Board-mounted counter records on-off counts in real time, supports predictive maintenance, reducing downtime.

Power-off state retention: Locks the relay's state after power-off, no need for reconfiguration upon restart, enhancing system stability with NI.

VI. Application Scenarios

High-frequency automated testing of semiconductors / electronic components, precise signal selection and routing for multiple pins.

Automotive electronic testing, detection of high-frequency signals, low-voltage control circuits on/off and state retention.

Industrial data acquisition systems, multipoint sensor signals multiplexing and switching.

Industrial ATE equipment, precise control signal multiplexing and long-term值守 with small and medium power loads.

Laboratory research and development platform， high-frequency signal routing， loop switching， comparison testing， and low-power verification.

Large-scale distributed measurement and control systems， high-density switch array， unified scheduling of multiple high-frequency / precise test signals.

Battery-powered， low-power long-term monitoring system， using latch characteristics to reduce energy consumption.

VIII. Usage and Maintenance Instructions

Usage points

Installation： Insert into a 3U standard slot， tighten the panel screws， keep away from strong vibration and strong electromagnetic interference； PXIe chassis should preferentially use mixed slots.

Connection： Use matching 200-pin LFH cables， gently insert and remove； use shielded cables for precise/high-frequency signals and reliably ground them to reduce interference.

Electrical limits： Strictly follow the 100 V/1 A rated parameters， prohibit overpressure and overcurrent； connect a shunt diode for inductive loads to prevent reverse high voltage from damaging contacts with NI.

Trigger mode： Use software for debugging trigger； use PXI hardware trigger for multi-module synchronization / high-speed scanning to ensure precise timing.

Power-on specification： Connect before powering on， unplug signal cables after power off， prohibit plugging and unplugging while powered on； latch state is automatically maintained after power off， no need to reconfigure.

Maintenance instructions

Regular inspection： Inspect 200-pin LFH connectors quarterly， clean dust， check for loose oxidation， ensure good contact.

Life management： Read on-off counts with NI-SWITCH regularly， plan to replace relays in advance when the load condition approaches 1×10⁵ times (supports on-site single-path replacement).

Environmental control： Maintain dry and ventilated conditions， temperature 0~55 ℃， avoid condensation and dust accumulation， prevent contact oxidation.

Fault handling： First check wiring， grounding and trigger configuration for channel abnormalities； single-path relay failure can be replaced on-site without replacing the entire module. Storage requirements: Disconnect the cables when the equipment is not in use. Install dust-proof protection on the interface. Store it in a dry environment ranging from -20 to 70 ℃, and keep it away from high temperatures, corrosive substances and strong magnetic fields. 

Calibration: It is recommended to conduct a functional verification once a year. Test the on-off status, conduction resistance, bandwidth and retention performance to ensure the test accuracy.