NI PXI-2503 Low-Voltage Multiplexer/Matrix Relay Switch

The NI PXI-2503 is a low-voltage multiplexer/matrix relay switch module for automated test and measurement applications. Built with electromechanical relays, it delivers high-density signal routing with configurable topologies including 1-wire 48×1 multiplexer, 2-wire 24×1 multiplexer, and 2-wire 4×6 matrix configurations. The module operates on the PXI Hybrid bus and supports up to 48 channels with a 1,024-step scan list for deterministic scanning. Electromechanical relay construction ensures low thermal EMF (<2 µV differential), critical for precision measurements with low-voltage sources like thermocouples. Maximum switching ratings are 60 VDC or 30 VAC at 1 A per channel with 30 W maximum switching power. DC path resistance remains <1 Ω initially and typically stays low throughout relay life. The module achieves 100 cycles/s typical scan rate with 3 ms typical relay operate time and 1.5 ms release time. Settling time varies with cable length and required accuracy; 6 in. cable at 0.012% accuracy settles in 8.5 µs with output buffer. Expected mechanical life reaches 5×10⁷ cycles; electrical life at maximum load is 2×10⁵ cycles. A 4-wire analog bus supports expansion of switching solutions. RF bandwidth extends to 10 MHz typical with 50 Ω termination.

– Technical Specifications

• Maximum Switching Voltage: 60 VDC / 30 VAC
• Maximum Switching Current: 1 A per channel
• Maximum Switching Power: 30 W (37.5 VA) per channel
• DC Path Resistance: 2 Ω end-of-life
• Thermal EMF (Differential): <2 µV
• Minimum Switch Load: 10 µA, 10 mV
• Relay Operate Time: 3 ms typical, 5 ms maximum at 20 °C
• Relay Release Time: 1.5 ms typical, 5 ms maximum at 20 °C
• Scan List Capacity: 1,024 steps
• Maximum Scan Rate: 100 cycles/s or 100 channels/s typical
• Switching Bandwidth: 10 MHz
• Mechanical Relay Life: 5×10⁷ cycles
• Electrical Relay Life: 2×10⁵ cycles at maximum load
• Bus Type: PXI Hybrid
• Relay Type: Electromechanical

– Key Features

• Configurable topologies: 1-wire 48×1, 2-wire 24×1, 2-wire Dual 12×1, 2-wire Quad 6×1, 4-wire 12×1 multiplexer, and 2-wire 4×6 matrix
• Support for 6, 12, 24, or 48 channel configurations
• 4-wire analog bus for solution expansion
• Low thermal EMF enables accurate low-voltage measurements
• High channel density with deterministic scanning

– Typical Applications

• Automated test systems for low-voltage analog signals
• Thermocouple signal routing and measurement
• Multi-channel data acquisition switching
• Flexible matrix signal routing in production test

– Compatibility & Integration

The PXI-2503 integrates with terminal block accessories including the TB-2606 for 2-wire 4×6 matrix configuration. It operates within the PXI Hybrid ecosystem for modular test automation.