Model Nomenclature

• PXI: PCI eXtensions for Instrumentation (3U modular instrumentation bus).

• 8420: NI serial interface series; 842x = RS‑232 focused.

• Suffix (/2, /4, /8, /16): Number of RS‑232 ports.

• PXI‑8420: Non‑isolated RS‑232; sibling models include isolated PXI‑8422 and RS‑485 PXI‑8421.

Technical Specifications

• Form Factor: 3U, single‑slot PXI.

• Ports: 2/4/8/16 × RS‑232 (EIA‑232).

• Baud Rate: 57 b/s to 460 kb/s; supports non‑standard rates (±1% accuracy).

• FIFOs: 64‑byte transmit / 64‑byte receive per port.

• Handshaking: RTS/CTS hardware handshake; XON/XOFF software flow control.

• Isolation: Non‑isolated (2 kV isolated version: PXI‑8422).

• Connector Types:

  • /2: DB‑9 male

  • /4: 10‑position modular jacks

  • /8: 68‑pin SCSI

  • /16: 100‑pin SCSI

• Power: 5 V DC from PXI backplane; typical ~1.2 A.

• Environment: Operating 0–55 °C; storage ‑20–70 °C; humidity 10–90% non‑condensing.

• Driver Support: NI‑Serial, LabVIEW, Measurement Studio; Windows compatibility.

Interface & Communication Configuration

• Front‑panel I/O: Port‑specific connectors (DB‑9/modular/SCSI) with breakout cables/boxes for standard DB‑9 devices.

• PCI Interface: Plug‑and‑Play; compatible with 3.3 V/5 V PCI signaling.

• Port Configuration: Each port independently set for baud rate, data bits (5–8), parity (none/even/odd), stop bits (1/1.5/2).

• Interrupts: Shared interrupts across ports to minimize system resource usage.

• Data Transfer: DMA‑capable for high throughput, low CPU overhead.

Core Features

• High‑Density Serial Expansion: Up to 16 RS‑232 ports in one slot; ideal for multi‑instrument test systems.

• Wide Baud Rate Flexibility: Supports standard and custom baud rates up to 460 kb/s.

• FIFO Buffering: 64‑byte FIFOs reduce CPU load and prevent data loss at high speeds.

• Legacy Compatibility: Works with RS‑232‑based instruments, PLCs, modems, and printers.

• Easy Integration: Plug‑and‑Play; NI‑Serial drivers for LabVIEW and common OSes.

• Cost‑Effective Connectivity: Non‑isolated design for cost‑sensitive, benign‑EMI environments.

Application Scenarios

• Automated Test Systems: Control multiple serial instruments (e.g., power supplies, meters, scanners) in aerospace, semiconductor, and automotive test benches.

• Industrial Automation: Connect PXI systems to PLCs, HMIs, and serial I/O modules on factory floors.

• Laboratory & Research: Data logging, device control, and serial communication with legacy lab equipment.

• Legacy System Upgrades: Add modern PXI capability while retaining existing RS‑232 devices.

• POS & Peripheral Control: Embed serial connectivity for printers, scanners, and custom serial peripherals.

Usage & Maintenance Instructions

Installation & Configuration

1. Insert into a 3U PXI chassis slot; secure the front panel.

2. Connect breakout cables/box to front‑panel connector(s); attach DB‑9 serial devices.

3. Power on the chassis; the OS will detect the card via Plug‑and‑Play.

4. Install NI‑Serial drivers and configure ports in NI‑Serial or Device Manager.

5. In LabVIEW, use VISA functions to open/close ports and configure communication parameters.

Daily Maintenance

• Inspect cables and connectors for wear, damage, or loose connections.

• Keep the module and chassis clean, dry, and within rated temperature/humidity.

• For EOL units, stock spare modules and cables to avoid downtime.

• Monitor communication via NI‑Serial tools or LabVIEW VISA traces for errors.

• Store idle modules in anti‑static bags in a dry environment.

Safety & Disposal

• Avoid hot‑swapping cables or modules when powered on.

• Do not expose to excessive EMI, moisture, or temperature beyond ratings.

• Dispose of EOL modules per local electronic waste regulations.