Description

 

NI PXI-8431/8 (often written as PXI-84318) – 8‑Port RS‑485/RS‑422 Interface for PXI Serial Connectivity

If you’re building a PXI system that needs reliable multiport serial, the NI PXI-8431/8 hits a sweet spot. It brings eight independent RS‑485/RS‑422 ports into a single 3U PXI slot, so you can talk to PLCs, drives, barcode scanners, motion controllers, and distributed sensors without juggling multiple cards. One thing I appreciate is how it scales—drop it into an existing chassis, install NI‑Serial, and you’re typically up and running in minutes. For production test or facility upgrades, that kind of predictability seems to be the real win.

Order Placement Process and Guarantees

• Warranty: 365 days
• Delivery time: Typically 1 week if in stock; no more than 1 month at the latest
• Payment: 50% advance payment, full payment prior to delivery
• Express options: FedEx, UPS, DHL

Key Features

• Eight RS‑485/RS‑422 ports – Consolidates multi-drop and point‑to‑point links in one PXI slot, helpful when cabinet space is tight.
• High‑speed serial – Supports data rates up to 3 Mb/s per port in many cases, depending on cabling and topology.
• 2‑wire and 4‑wire modes – Full‑duplex RS‑422 or half/full‑duplex RS‑485, so you can match legacy field devices without drama.
• Front VHDCI high‑density connector – Break out to eight DB‑9 or screw‑terminal ports using standard NI cables/terminal blocks.
• NI‑Serial driver + NI‑VISA – Integrates cleanly with LabVIEW and common Windows environments; typically no custom kernel work needed.
• PXI single‑slot, 3U form factor – Easy drop‑in for test benches and production PXI chassis.
• Status indicators – Per‑port activity/status LEDs make field diagnostics faster than guessing from software alone.
• Multi‑node RS‑485 networks – Commonly used for up to 32 nodes per port; termination/biasing practices still apply.

Technical Specifications

Brand / Model	NI PXI-8431/8 (often written as PXI-84318)
HS Code	8471.80 (Other units of automatic data processing machines)
Form Factor	PXI, 3U, single‑slot module
Power Requirements	Powered from PXI backplane; typical consumption is low for a single‑slot serial interface
Dimensions & Weight	Standard PXI 3U card (approx. 160 mm board depth); weight typically < 0.5 kg
Operating Temperature	0 °C to 55 °C (typical for NI PXI serial modules)
Signal I/O Types	8× RS‑485/RS‑422 ports; differential signaling; 2‑wire or 4‑wire operation
Max Data Rate	Up to 3 Mb/s per port (application‑dependent)
Front Connector	High‑density 68‑pin VHDCI; breakout to 8× serial ports via cable/terminal accessory
Communication Interfaces	PXI backplane (PCI) to host; RS‑485/RS‑422 to field devices
Software Support	NI‑Serial driver, NI‑VISA; commonly used with LabVIEW and Windows
Installation Method	Direct insertion into PXI chassis; secure with front‑panel screws

Related or Supporting Products

• NI PXI‑8431/2 – Same family, 2 ports. Good when you only need a couple of channels.
• NI PXI‑8431/4 – 4 ports; typically a balanced option between density and cost.
• NI PXIe‑8431/8 – PXI Express version for newer PXIe chassis; similar functionality with an updated backplane interface.
• NI PXI‑8432/8 – 8‑port RS‑232 alternative if your equipment is single‑ended instead of differential.
• NI breakout accessories – 68‑pin VHDCI to 8× DB‑9 or screw‑terminal breakout cables/blocks for quick field wiring.

Installation & Maintenance

• Chassis & environment – Install in a standard PXI 3U chassis with adequate front‑to‑back airflow. Keep ambient within 0–55 °C and avoid dust buildup around the front panel.
• Wiring practices – Use twisted‑pair, shielded cable for RS‑485/422. Terminate at the bus ends and apply biasing where required; this alone fixes most intermittent communication issues.
• Grounding & ESD – Connect shields at a single reference point to reduce ground loops. Handle the module with ESD precautions when outside the chassis.
• Driver & firmware – Keep NI‑Serial and NI‑VISA up to date. From my experience, driver updates often add device fixes that improve stability on higher baud rates.
• Routine checks – Inspect VHDCI cabling, strain relief, and terminal screws quarterly. Verify termination resistors after any field rewiring. Clean intake filters on the chassis as needed.
• Troubleshooting tip – If a line is noisy, drop the baud rate and check segment lengths; RS‑485 can run long distances (hundreds of meters), but speed and topology have a big say in what’s reliable.

Quality & Certifications

• Certifications – CE, RoHS compliant; designed for use in industrial test and measurement environments.
• Manufacturer’s warranty – NI typically provides a limited hardware warranty (commonly 1 year) with service extensions available.
• Our coverage – 365‑day warranty on supply; replacements or repairs coordinated quickly to keep downtime low.

You might notice that most teams adopt the PXI‑8431/8 when they want to consolidate multiple RS‑485 lines—like tying in VFDs, weigh modules, and barcode readers to a single controller. A recent customer migrated from four USB‑serial hubs to this card and saw far fewer dropouts, mainly because the cabling got simpler and the driver stack was unified. That’s a small change that, in many cases, pays off immediately.