National Instruments 781421-34 Electromechanical Relay Matrix Module

The National Instruments 781421-34 (NI-2834B) is an electromechanical relay matrix module designed for SwitchBlock systems. This module is tailored for high power applications that makes it suitable for routing signals in complex testing environments. It is capable of operating as a standalone relay card or can be expanded in a single SwitchBlock carrier or PXI chassis. The primary function of the module is to allow dynamic signal routing and reduce the need for manual rewiring. This simplifies signal path switching between various instruments like oscilloscopes, digital multimeters (DMMs), waveform generators, and power supplies.

This 781421-34 module features a maximum switching voltage of 100 V (CAT I) between rows and columns or row to ground. It can support a maximum switching current of 2.0 A per channel and a maximum switching power of 60 W. The system can run up to 8 channels simultaneously at the maximum current. The relay matrix ensures low thermal electromotive force (EMF) of less than 10 μV, which is critical for maintaining signal integrity. This electromechanical relay matrix module offers excellent isolation and crosstalk performance which are essential for maintaining signal quality in high-density test setups. It has a typical bandwidth of ≥10 MHz with minimal signal loss while isolation in an open channel at 1 MHz is approximately 45 dB. Crosstalk is also well-managed with values as low as -75 dB at 10 kHz.

This NI 781421-34 module features electromechanical latching relays made from palladium-ruthenium with a gold covering that is designed for a high number of switching cycles. The mechanical relay life can reach up to 100 million cycles with no load while the electrical life varies depending on the voltage and current with a maximum of 2.5 million cycles at lower power levels. 

The relay matrix module is compact with dimensions of 11.2 cm × 1.2 cm × 17.1 cm and weighs just 373 g. It operates efficiently with power requirements of 20 W at 5 V and 5 W at 3.3 V. The module is designed for indoor use in ambient temperatures ranging from 0°C to 55°C and can be stored in temperatures between -20°C and 71°C.