PXI-8431: Product OverviewThe National Instruments PXI-8431 is a four-port isolated serial interface module designed for PXI-based systems operating in industrial environments where electrical noise, ground potential differences, and voltage transients present significant challenges to communication reliability. This module functions as a robust serial communication gateway, providing galvanic isolation between the PXI chassis and connected serial devices to ensure data integrity and equipment protection in harsh electrical conditions.Installed in a PXI chassis, the module operates with four independent serial channels, each featuring 2500V RMS of isolation to protect the host system from ground loops, voltage spikes, and common-mode noise. Each channel is software-configurable for either RS-232 or RS-485 electrical standards, providing flexibility for connecting to various industrial equipment. The isolation barrier withstands significant potential differences between devices connected to different power circuits or located in areas with varying ground potentials, which is common in large industrial facilities, power generation plants, and distributed control systems.
NI PXI-8431
PXI-8431: Technical Specifications
• Model Number: PXI-8431
• Manufacturer: National Instruments
• Product Type: PXI Isolated Serial Interface Module
• Number of Ports: 4 independent isolated serial ports
• Isolation Rating: 2500V RMS continuous (port-to-port and port-to-bus)
• Supported Standards: RS-232, RS-485 (software selectable per port)
• Maximum Data Rate: 1 MBaud per port
• Data Bits: 5, 6, 7, or 8 bits
• Stop Bits: 1, 1.5, or 2 bits
• Parity: None, odd, even, mark, space
• Flow Control: Hardware (RTS/CTS) and software (XON/XOFF)
• FIFO Buffers: 128-byte per port
• Connector: 20-position screw terminal
• Operating Voltage: +5 VDC from PXI backplane
• Operating Temperature: -40°C to 85°C
• Isolation Voltage: 2500V RMS (continuous)
• Common-Mode Rejection: >25 kV/μs
• Driver Support: NI-VISA, NI-Serial
• API Support: LabVIEW, C, C#, .NET
NI PXI-8431
Core Features & Customer ValueHigh-Voltage Isolation Protection: The 2500V RMS isolation rating provides critical protection for both the host system and connected equipment in industrial environments where ground potential differences can exceed hundreds of volts. This isolation prevents ground loops that can cause communication errors, equipment damage, and measurement inaccuracies. For engineers designing systems for industrial plants, substations, or other facilities with harsh electrical environments, this protection ensures communication reliability and reduces downtime caused by electrical noise issues.Extended Temperature Operation: The wide operating temperature range of -40°C to 85°C enables deployment in non-climate-controlled environments such as outdoor enclosures, factory floors, and electrical substations where temperature extremes are common. This reliability across temperature variations reduces the need for environmental control systems and expands the possible installation locations for PXI-based test and control systems.Screw Terminal Connectivity: The 20-position screw terminal connector provides secure, reliable connections that resist vibration-induced loosening, which is common in industrial environments. This connection method also facilitates the use of standard industrial wiring practices and eliminates the need for special adapters or breakout boxes, simplifying installation and maintenance in field applications.Typical ApplicationsIn electrical power substation monitoring, the module communicates with protective relays, power quality meters, and other serial devices while withstanding the high-voltage transients and ground potential differences present in high-voltage switchyards.For industrial process control systems, it provides communication to field devices such as motor drives, weighing systems, and process controllers located in electrically noisy environments with significant ground potential variations.In transportation system monitoring, the interface connects to wayside equipment and sensors along railway lines where long cable runs are susceptible to induced voltages and lightning strikes.
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