Description

The National Instruments SCXI-1141 is a specialized latching relay output module engineered for applications where power efficiency, state retention during outages, and minimal heat generation are critical. Designed for the SCXI (Signal Conditioning eXtensions for Instrumentation) platform, the SCXI-1141 (182610D-01) features eight independent channels, each containing four single-pole single-throw (SPST) latching electromechanical relays—totaling 32 relays per module. Unlike conventional relays that require continuous coil current to maintain state, the latching design of the NI SCXI-1141 only consumes power during the brief moment of switching; once set or reset, the relay contact position remains stable even when system power is removed. This makes it uniquely suited for battery-operated test systems, aerospace avionics validation, remote field instrumentation, and fail-safe control architectures.

Positioned as a niche but indispensable component within NI’s modular ecosystem, the National Instruments SCXI-1141 addresses scenarios where thermal management and power budget constraints rule out standard relay modules. Its screw-terminal interface (compatible with TB-2641) simplifies wiring to sensors, signal paths, or low-power actuators, while its compatibility with NI-DAQmx and LabVIEW ensures seamless integration into existing SCXI/PXI hybrid systems. Although newer PXI-based solid-state switches offer higher speed, the SCXI-1141 remains unmatched for applications requiring true mechanical isolation, zero static power draw, and guaranteed state retention through power interruptions—key requirements in defense, space, and portable diagnostic equipment.

NI SCXI-1141

Technical Specifications

Main Features and Advantages

True latching relay technology with zero hold current: The defining feature of the NI SCXI-1141 is its use of bistable latching relays that require only a short current pulse to change state—no continuous power is needed to maintain contact position. This eliminates steady-state coil heating and drastically reduces overall system power consumption, making the SCXI-1141 ideal for battery-powered portable testers, UAV ground support equipment, or satellite simulation rigs where every milliwatt counts.

State retention through power loss for fail-safe operation: In the event of a system shutdown or unexpected power interruption, the SCXI-1141 preserves its last switching state indefinitely. This is critical in safety-critical applications such as emergency shutoff circuits, calibration reference routing, or spacecraft subsystem isolation, where unintended relay reset could compromise data integrity or hardware safety.

Low thermal footprint enables high-density deployment: Because the NI SCXI-1141 generates no sustained heat from relay coils, multiple modules can be installed side-by-side in a single SCXI chassis without thermal throttling or derating concerns. This contrasts sharply with standard relay modules, which often require slot spacing for cooling in high-channel-count systems.

Mechanical contact reliability with signal-level precision: Despite its low-power design, the SCXI-1141 uses gold-flashed contacts rated for 1 A at 30 VDC, ensuring reliable switching of low-level analog signals (e.g., thermocouple or strain gauge paths) without introducing offset voltages or contact resistance drift—unlike reed or solid-state alternatives. This makes it suitable not just for power switching, but also for precision signal routing in metrology labs.

Seamless software control via standard NI drivers: Through NI-DAQmx, each relay on the NI SCXI-1141 is individually addressable using intuitive channel names (e.g., “SCXI1Mod3/relay0”). LabVIEW VIs provide pre-built functions for SET/RESET operations, enabling rapid development of complex switching sequences without low-level firmware programming.

Application Field

In aerospace ground support equipment, the NI SCXI-1141 routes power and signals to satellite payload simulators during thermal vacuum testing. Its ability to retain switch states during chamber power cycling ensures test continuity across multi-day campaigns—critical when requalification costs exceed $500k per hour.

Within defense electronics validation, the SCXI-1141 controls RF path selection in radar module testers powered by mobile generators. The near-zero static power draw extends generator runtime, while latching behavior prevents unintended antenna disconnection during brownouts—a key requirement under MIL-STD-704 power quality standards.

In portable medical device certification labs, the NI SCXI-1141 switches ECG lead configurations or infusion pump test loads in battery-operated compliance testers. Regulatory agencies (e.g., FDA, IEC 60601) often require verification that devices behave correctly during power transients—the SCXI-1141’s state retention directly supports this validation.

For remote environmental monitoring stations, the SCXI-1141 toggles sensor excitation or calibration references in solar-powered DAQ systems. By eliminating relay coil drain, the module helps extend operational life between maintenance visits in Arctic or desert deployments where service access is limited.

In semiconductor parametric test systems, the SCXI-1141 isolates sensitive SMU (Source Measure Unit) channels during high-voltage stress tests. Its mechanical contacts prevent leakage currents that could corrupt femtoamp-level measurements—something solid-state switches cannot guarantee.

NI SCXI-1141

Related Products

SCXI-1140: Non-latching version with higher current rating (2 A) but continuous coil power required
SCXI-1142: Reed-relay module for high-speed, low-current signal switching (not latching)
TB-2641: Dedicated 50-pin screw-terminal block designed for SCXI-1141 wiring
PXI-2530: High-density matrix switch for complex signal routing (solid-state, not latching)
SCXI-1349: MXI interface module for connecting SCXI chassis to PXI controllers
SCXI-1163: High-power non-latching relay module (2.5 A) for industrial loads
PCI-6528: PCI-based isolated digital I/O with Form C relays—non-latching alternative
NI 2720: PXI modular switch with latching relays, successor in PXI form factor