NI-9426

The NI-9426 is a high-density C Series digital input module designed for CompactRIO and CompactDAQ systems. It provides 32 simultaneously sampled digital input channels compatible with 24 V industrial logic levels, making it suitable for industrial automation, machine monitoring, embedded control, and high-channel-count digital acquisition systems.

The module is optimized for:

• Industrial switch monitoring
• PLC signal acquisition
• Sensor status monitoring
• FPGA-based deterministic systems
• Embedded automation
• Machine feedback acquisition
• Distributed industrial systems
• Factory automation

Unlike the NI-9425, which uses sinking inputs, the NI-9426 uses a sourcing digital input architecture, making it ideal for industrial systems using sinking-output devices.

Digital Input Architecture

The NI-9426 provides:

• 32 digital input channels
• 24 V industrial logic compatibility
• Sourcing digital input architecture
• 7 μs maximum update time
• Simultaneous channel sampling
• High-density 37-pin DSUB connectivity

Key specifications include:

The module supports direct connection to:

• Industrial switches
• PLC outputs
• Industrial transducers
• Relay outputs
• Industrial sensors
• Machine status signals
• Sinking-output field devices

Sourcing Digital Input Operation

The NI-9426 uses a sourcing digital input architecture.

In this configuration, the module sources current to the external field device, while the connected device sinks current to ground.

This architecture is commonly used with:

• NPN sensors
• Sinking PLC outputs
• Industrial transistor outputs
• Open-collector industrial devices

Digital logic thresholds include:

The module also includes hysteresis for improved industrial noise immunity.

High-Density Industrial Monitoring

One of the major advantages of the NI-9426 is its 32-channel density.

This allows engineers to monitor a large number of industrial digital signals while minimizing CompactRIO or CompactDAQ slot usage.

Typical applications include:

Machine Status Monitoring

The NI-9426 can acquire dozens of industrial status signals simultaneously.

PLC Integration

The module is commonly used to read sinking-output PLC signals and machine control states.

Factory Automation

The NI-9426 enables centralized monitoring of industrial sensors and control signals.

Embedded FPGA Systems

CompactRIO FPGA systems can use the NI-9426 for deterministic high-speed industrial signal acquisition.

Compared with lower-channel digital input modules, the NI-9426 significantly reduces chassis expansion requirements and wiring complexity.

Fast Digital Acquisition Performance

The NI-9426 supports a 7 μs maximum update/transfer time, enabling deterministic high-speed digital acquisition.

Additional timing specifications include:

This performance makes the module suitable for:

• High-speed industrial automation
• Trigger systems
• Embedded FPGA logic
• Event-driven systems
• Deterministic machine monitoring

Compared with conventional PLC digital inputs, the NI-9426 offers much lower latency and faster update performance.

FPGA Integration and Deterministic Processing

When installed in CompactRIO systems, the NI-9426 interfaces directly with FPGA hardware.

Engineers can implement:

• FPGA-based digital logic
• Deterministic machine control
• Real-time automation
• High-speed event capture
• PWM monitoring
• Industrial protocol handling
• Encoder and trigger processing

The CompactRIO FPGA architecture enables deterministic low-latency digital acquisition that is difficult to achieve with PC-based I/O systems.

This architecture is especially useful for:

• Industrial robotics
• Embedded machine control
• Motion systems
• Industrial automation
• Real-time embedded systems

Isolation and Industrial Protection

The NI-9426 includes industrial-grade electrical protection.

Isolation specifications include:

Additional protection features include:

• 30 VDC maximum Vsup-to-channel protection
• Reverse-voltage protection
• Industrial EMC robustness
• Improved noise immunity

These protections improve reliability in harsh industrial environments.

Connectivity and Platform Support

The NI-9426 uses an industry-standard 37-pin DSUB connector, enabling compatibility with a wide range of industrial accessories and cable assemblies.

Typical accessories include:

• NI-9933 connector kit
• NI-9923 screw-terminal accessory
• Custom DSUB breakout assemblies

Supported platforms include:

• CompactRIO
• CompactDAQ
• Single-Board RIO
• EtherCAT systems
• R Series expansion chassis

Supported software includes:

• LabVIEW
• LabVIEW FPGA
• NI-DAQmx
• NI-RIO
• C/C++
• Python
• MATLAB
• .NET integration

Rugged Industrial Design

The NI-9426 is designed for industrial deployment.

Industrial specifications include:

• Operating temperature: -40 °C to 70 °C
• Storage temperature: -40 °C to 85 °C
• Random vibration: 5 g RMS
• Shock resistance up to 50 g
• IP40 protection

The module is suitable for:

• Factory automation
• Transportation systems
• Industrial monitoring
• Embedded industrial machines
• Energy infrastructure
• Distributed industrial cabinets

The NI-9426 also supports hazardous-location deployment in certified CompactRIO systems.

Application-Oriented Use Cases

Industrial Sensor Monitoring

The NI-9426 is widely used for monitoring industrial sensor states and machine feedback signals.

PLC and Machine Integration

The module supports direct acquisition of sinking PLC outputs and industrial machine signals.

Embedded FPGA Systems

CompactRIO FPGA systems can use the NI-9426 for deterministic industrial automation and trigger handling.

Factory Automation

The high channel count makes the NI-9426 ideal for centralized industrial digital monitoring systems.

Comparison with Similar Modules

Compared with the NI-9425, the NI-9426 uses sourcing inputs instead of sinking inputs. Compared with the NI-9423, the NI-9426 focuses more on high-density industrial monitoring rather than ultra-high-speed acquisition.

Conclusion

The NI-9426 is a rugged high-density 32-channel industrial digital input module designed for CompactRIO and CompactDAQ systems requiring deterministic 24 V digital signal acquisition.

Its combination of:

• 32 digital input channels
• 24 V industrial logic compatibility
• Sourcing input architecture
• 7 μs update performance
• FPGA integration
• Industrial ruggedness
• High-density DSUB connectivity

makes it an excellent solution for industrial automation, PLC integration, machine monitoring, embedded control systems, and deterministic FPGA-based industrial applications.