Product Overview
The National Instruments PXI-2569 is a relay module for PXI systems. It provides 100 single pole single throw relay channels in a single PXI slot, allowing a test system to connect and disconnect signals to many devices under test. The module is part of the NI PXI switch family and is used in production test, design validation, and laboratory automation.
Relay switching is a fundamental function in automated test because instruments must be shared across many test points. A high channel count relay module reduces the number of separate switch boxes and cables in a rack, which improves integration and maintainability. The PXI-2569 is designed to provide dense switching while remaining controllable from the same software environment as other PXI instruments.
Relay Channels and Architecture
The module provides 100 single pole single throw channels. Each channel opens or closes a single signal path under software control. Channels are grouped for wiring convenience, and the module documentation defines the connector pin mapping so that engineers can plan cable assemblies and terminal blocks. Careful mapping of channel to test point is essential for maintainable test software.
Single pole single throw relays are suited to simple connect and disconnect functions, such as routing an instrument to a test point, selecting a load, or isolating a faulty channel. More complex switching networks can be built by combining multiple modules. Engineers should confirm whether the application requires additional switching topologies such as multiplexers or matrices.
Switching Characteristics
Relay switching involves mechanical contact movement, so settling time and contact life are important design considerations. Test sequences should allow adequate settling time after a relay closes before a measurement is taken. Contact wear depends on the voltage and current being switched, so the module should be used within its specified switching limits.
For low level measurements, thermal voltages and contact resistance can affect accuracy. Engineers should allow the system to reach thermal equilibrium and should verify measurement performance with representative switching patterns. Where very low level signals are measured, special care in cable selection and shielding is required.
PXI Integration
The PXI-2569 installs in a compatible PXI chassis and communicates with the controller over the PXI backplane. It can be synchronized with DMMs, source measure units, digitizers, and other PXI instruments through trigger lines and timing resources. This allows switching operations to be coordinated with measurement steps in a defined sequence.
The module is supported by NI switch driver software and can be programmed with LabVIEW, LabWindows/CVI, Measurement Studio, and other compatible development environments. Engineers can create switching sequences that connect instruments to different test points, route signals to measurement devices, and isolate channels for fault analysis.
System Design Considerations
When designing a switching system, engineers should consider the number of test points, the signal types being switched, the required isolation, and the expected switching frequency. Higher switching frequency increases contact wear and may require a different switching technology. The PXI-2569 is best suited to applications where moderate switching rates and low power signals are involved.
Wiring practice affects both reliability and measurement quality. Shielded cable, separation of signal and power conductors, and secure connector fastening reduce noise and intermittent faults. Documentation of the channel map, cable design, and test sequence helps maintain the system as it evolves.
Typical Applications
Automated test signal routing and device switching
Production test with multiple test points
Instrument to device under test connection
Load selection and channel isolation
High channel count switching systems
PXI based automated test racks
The PXI-2569 provides 100 single pole single throw relay channels in a PXI module. Its channel density and PXI integration make it suitable for automated test switching and signal routing applications.
