PXI-2501 48-Channel FET Multiplexer and Matrix Switch
The PXI-2501 is a configurable low-voltage PXI multiplexer and matrix switch designed for fast automated signal routing. Its solid-state FET architecture supports rapid scanning, flexible 1-wire, 2-wire and 4-wire topologies, and switching of low-voltage measurement signals.
The module is particularly useful in automated data acquisition, sensor measurement, resistance testing, process monitoring and production test systems. Depending on the selected topology and terminal block, the PXI-2501 can operate as a multiplexer or a 2-wire 4×6 matrix.
Key Features of the PXI-2501
- 48-channel configurable PXI multiplexer
- Solid-state FET switching architecture
- 1-wire, 2-wire and 4-wire measurement support
- 2-wire 4×6 matrix configuration
- Maximum scan rate of 15,000 channels per second
- ±10 VDC maximum switching-voltage range
- 400 kHz typical bandwidth at the -3 dB point
- Fast microsecond-level settling
- Dedicated cold-junction temperature sensor channel
- Optional sockets for process-current shunt resistors
- PXI and front-panel hardware trigger support
- 68-pin male SCSI front-panel connector
- NI-SWITCH and NI Switch Executive compatibility
PXI-2501 Technical Specifications
| Product Model | PXI-2501 |
|---|---|
| Part Number | 777696-01 |
| Product Type | Low-voltage FET multiplexer and matrix switch |
| Switch Technology | Solid-state FET |
| Maximum Channel Count | 48 channels in 1-wire mode |
| Supported Topologies | 1-wire 48×1; 2-wire 24×1, dual 12×1 or quad 6×1; 4-wire 12×1; 2-wire 4×6 matrix |
| Maximum Switching Voltage | ±10 VDC or 7 VAC |
| Typical FET On-Resistance | 50 Ω |
| Maximum FET On-Resistance | 85 Ω at 25°C; 100 Ω at 85°C |
| Typical Bandwidth | 400 kHz at -3 dB; 1 MHz at -10 dB |
| Maximum Scan Rate | 15,000 channels/s |
| Trigger Inputs | PXI trigger lines 0 through 7 and front-panel trigger |
| Minimum PXI Trigger Pulse | 70 ns |
| Minimum Front Trigger Pulse | 500 ns |
| Front Connector | 68-pin male SCSI |
| Operating Temperature | 0°C to 50°C |
| Module Format | 3U, one-slot PXI module |
| Weight | Approximately 174 g |
PXI-2501 Part Number and Accessories
| Item | Part Number | Description |
|---|---|---|
| PXI-2501 | 777696-01 | 48-channel configurable FET multiplexer and matrix module |
| TB-2605 | 777878-01 | Screw-terminal multiplexer terminal block with analog-bus connections |
| TB-2606 | Verify when ordering | Terminal block that configures the module as a 2-wire 4×6 matrix |
| TBX-68S | 777716-01 | DIN-rail-mounted 68-position screw-terminal block |
The terminal accessory determines how the PXI-2501 signals are presented to the test fixture. Use the TB-2605 for multiplexer and general measurement wiring or the TB-2606 when the required topology is a 2-wire 4×6 matrix.
Configurable Multiplexer Topologies
The PXI-2501 can be configured as a 48×1 single-wire multiplexer when maximum channel density is required. For differential measurement systems, the module can operate as a 24×1, dual 12×1 or quad 6×1 two-wire multiplexer.
A 12×1 four-wire topology is available for measurements requiring separate source and sense conductors. This is useful for resistance measurements where lead and fixture resistance must be reduced through Kelvin connections.
2-Wire 4×6 Matrix Operation
When combined with the TB-2606 terminal block, the module can operate as a 2-wire 4×6 matrix. This allows any of four row pairs to be connected to any of six column pairs under software control.
Multiple modules and terminal blocks can be combined to create larger matrix systems. The complete design must account for accumulated path resistance, FET leakage, capacitance and settling time.
Fast FET Switching
The PXI-2501 uses solid-state FET switches rather than electromechanical relays. This architecture provides fast, repeatable switching without the mechanical-contact wear associated with conventional relay modules.
Its maximum scan rate of 15,000 channels per second makes it suitable for applications requiring rapid measurement of many sensors or test points. Actual system throughput also depends on the measurement instrument, settling requirements and software configuration.
Cold-Junction and Process-Current Measurements
The module includes a dedicated temperature-sensor channel that can support cold-junction compensation when used with compatible thermocouple wiring and terminal accessories.
It also provides sockets that can accept precision 249 Ω shunt resistors. These resistors allow common 4–20 mA process-current signals to be converted into measurable voltage signals.
PXI-2501 Applications
- Automated sensor scanning
- Thermocouple and temperature measurement
- Four-wire resistance measurement
- 4–20 mA process-signal monitoring
- Production functional testing
- Environmental monitoring systems
- Low-voltage signal routing
- Data-logger channel expansion
- Automated test equipment
- Laboratory measurement automation
Integration with Digital Multimeters
The PXI-2501 can be used with a PXIe-4080 digital multimeter or another compatible PXI measurement instrument. The switch selects the test point while the DMM performs voltage, resistance or current-related measurements.
Hardware handshaking and triggering can coordinate switching with the instrument, reducing software overhead and improving repeatability.
NI-SWITCH Software Support
The PXI-2501 is controlled through the NI-SWITCH driver. Applications can select a topology, create routes, build scan lists, configure triggers and monitor module status.
NI Switch Executive can assign meaningful names to physical channels and routes. This simplifies programs containing multiple modules, instruments and test-fixture connections.
PXI-2501 Troubleshooting
The module is not detected in NI MAX
Verify that the module is fully installed in a compatible PXI or hybrid slot. Check chassis power, controller communication and the installed NI-SWITCH version.
A selected channel returns the wrong measurement
Confirm the active topology and terminal-block wiring. Channel names and pin assignments change between 1-wire, 2-wire, 4-wire and matrix configurations.
Measurements do not settle quickly enough
Review source impedance, cable length, fixture capacitance and instrument aperture. High source impedance or long cables can increase settling time beyond the module-only specification.
Resistance readings are higher than expected
Remember that the FET signal path has substantially more resistance than an electromechanical relay. Use four-wire measurement where appropriate and verify whether the module is suitable for the required resistance accuracy.
A 4–20 mA signal cannot be measured
Check that the required precision shunt resistor is installed correctly and that its power rating is suitable for the loop current. Verify the selected input range of the measurement instrument.
PXI-2501 vs PXI-2503
| Feature | PXI-2501 | PXI-2503 |
|---|---|---|
| Switch Technology | Solid-state FET | Electromechanical armature relay |
| Primary Advantage | Fast scanning and no mechanical wear | Lower closed-path resistance and greater signal flexibility |
| Typical Bandwidth | 400 kHz | Topology dependent |
| Best Suited For | Rapid low-voltage scanning | General-purpose precision switching |
Recommended Related Products
- PXI-2503 Multiplexer and Matrix Switch
- PXI-2530 High-Density Multiplexer
- PXI-2532 Matrix Switch
- PXIe-4080 Digital Multimeter
- View More NI PXI Modules
Frequently Asked Questions
What is the PXI-2501?
The PXI-2501 is a configurable FET-based PXI multiplexer and matrix switch for fast routing of low-voltage measurement signals.
How many channels does it provide?
It provides as many as 48 channels in its 1-wire 48×1 multiplexer configuration.
Can it perform four-wire measurements?
Yes. The module supports a 4-wire 12×1 topology for Kelvin resistance and related measurements.
Can the PXI-2501 operate as a matrix?
Yes. With the appropriate TB-2606 terminal block, it supports a 2-wire 4×6 matrix topology.
What is the maximum scan rate?
The specified maximum scan rate is 15,000 channels per second.
What is the PXI-2501 part number?
The commonly listed NI ordering part number is 777696-01.
Request a Quote for the PXI-2501
Contact us for current availability, lead time and project pricing for the PXI-2501 FET Multiplexer and Matrix Switch. We can also help identify compatible terminal blocks, PXI chassis, digital multimeters and alternative NI switch modules.
