NI PCI-8431/2 High-Performance 2-Port Serial Interface (RS485)

The NI PCI-8431/2 is a high-performance 2-port serial interface card for RS485 and RS422 communication over PCIe. It delivers deterministic, low-latency serial data transfer with support for baud rates from 2 to 3 Mbps, making it suitable for industrial automation, process control, and distributed sensor networks requiring reliable multi-device communication.

– Technical Specifications

Performance
• Maximum baud rate: 3 Mbps (RS485/RS422)
• Baud rate range: 2 baud to 3 Mbps (standard and nonstandard rates supported)
• Accuracy: 0.01% for standard baud rates; 1% for nonstandard
• Transmit/receive FIFOs: 128 bytes each
• Data transfer: High-speed DMA transfers with multithreading and multiprocessor support

Electrical Characteristics
• Power requirement: 500 mA to 700 mA at +5 VDC
• Voltage compatibility: 5 V and 3.3 V signaling environments
• Interface: PCIe

Connectivity
• Primary connector: Male DB-9 (RS-422/RS-485)
• Secondary connector: 68-pin VHDCI I/O
• Transceiver modes: Selectable 2-wire (half-duplex) and 4-wire (full-duplex)

Physical & Environmental
• Dimensions: 4.38 × 6.9 inches (10.67 × 14.22 cm)
• Weight: 0.20 lb (92 g)
• Operating temperature: 0 to 55 °C
• Storage temperature: –20 to 70 °C
• Operating humidity: 10 to 90% RH (non-condensing)

– Key Features

• Dual-port RS485/RS422 interface with selectable transceiver modes for mixed topology networks
• High-speed DMA architecture minimizes CPU overhead in multithreaded and multiprocessor environments
• Standard COM port emulation ensures compatibility with legacy serial communication software
• Flexible baud rate selection from 2 to 3 Mbps with ±1% nonstandard accuracy
• 128-byte FIFOs reduce interrupt latency and improve throughput stability

– Typical Applications

• Industrial process automation with distributed RS485 device networks
• Real-time monitoring systems requiring low-jitter serial communication
• Multi-sensor data acquisition across half-duplex and full-duplex topologies
• Legacy system integration with standard COM port-based software

– Compatibility & Integration

Fully compatible with Windows (XP, Vista, Windows 7, 2000) and LabVIEW Real-Time OS. Operates as standard PC COM ports, enabling direct use with existing serial drivers and applications without modification. Universal PCI design supports both 5 V and 3.3 V host environments.